Precision Fabrics Grp., Inc. v. Tietex Int'l, Ltd. (367 F. Supp. 3d 487, 2019)

THOMAS D. SCHROEDER, District Judge.

These patent infringement actions are before the court on two post-trial motions filed by Precision Fabrics Group, Inc. ("PFG") for relief from a jury verdict that found that Defendant Tietex International, Ltd. ("Tietex") did not infringe its U.S. Patents Nos. 8,796,162 ('162 Patent) and 8,501,639 ('639 Patent) for flame-retardant technology for fabrics. PFG renews its prior motion for judgment as a matter of law and moves in the alternative for a new trial. (Doc. 372.) After careful consideration and for the reasons set forth below, the motions will be denied.

I. BACKGROUND

PFG filed the first of these two actions on August 6, 2013, in the Middle District of North Carolina and, with the follow-on lawsuit, alleges that certain Tietex products incorporating flame-retardant fabrics infringe PFG's U.S. Patents Nos. 8,796,162 ('162 Patent) and 8,501,639 ('639 Patent). The patents-in-suit describe lightweight materials designed to retard fire for a variety of applications, including garments, furniture, appliances, and vehicles. (Doc. 112-1 at 2; Doc. 112-2 at 2.) Tietex developed a similar fabric that would operate as a flame-retardant cloth for mattresses. Up until October 2016, Tietex applied to its fabric a solution known as SV-X41, which was manufactured by Royal Adhesives and Sealants, Inc. ("Royal Adhesives").

Tietex concedes that for the approximately three-year period at issue, its accused fabrics met each of the limitations set forth in PFG's patents, with the exception of the claims requiring that the fabrics be coated with an "intumescent." Tietex contends that the SV-X41 coating it used is not an intumescent. The meaning of the term "intumescent" has been disputed throughout this litigation. After conducting a Markman hearing, the court adopted PFG's construction and held that "intumescent," as defined in PFG's patents, means "a substance that swells and chars upon exposure to heat or flame." (Doc. 57 at 20-21.) In so doing, the court denied Tietex's proposed claim construction based on a four-component definition. (Id. at 11.) Tietex subsequently conceded that its coating charred when exposed to heat or flame. (Doc. 133 at 7.) Thus, the parties agreed that the sole issue in PFG's infringement claims against Tietex was whether SV-X41 swells upon exposure to heat or flame.

PFG moved for partial summary judgment as to its claims against Tietex for infringement and Tietex's counterclaims alleging inequitable conduct and invalidity of PFG's patents. (Doc. 111.) PFG also moved to exclude the testimony of Tietex's expert, Dr. Richard Horrocks. (Doc. 116.) The court denied PFG's partial motion for summary judgment on its claims of infringement but granted its motion for summary judgment on Tietex's counterclaims. (Doc. 152 at 46.) After extensive consideration, the court granted in part and denied in part PFG's motion to exclude or limit the testimony of Dr. Horrocks. (Id. )

The parties filed a host of motions in limine prior to trial, including several directed toward the expert witnesses. Following transfer of the action to this district in the wake of TC Heartland LLC v. Kraft Foods Grp. Brands LLC, --- U.S. ----, 137 S.Ct. 1514, 197 L.Ed.2d 816 (2017), the case was tried to a jury for five days.

Central to PFG's case was the testimony of its expert, Gajanan Bhat, Ph.D. Dr. Bhat was qualified as an expert in the field of textiles, flame retardant finishes and coatings, and intumescent finishes and coatings. (Tr. at 479.) He testified that he tested the SV-X41 coating on successive occasions by exposing it, when applied to varying substrates, to heat and flame, several in response to criticisms by Tietex's expert. Each test applied various thicknesses of the coating, and Dr. Bhat reported that each resulted in measurable swelling of the SV-X41 to some degree. (Id. at 481, 588-90, 604-06.) For his measurements he used an electronic pressure foot, which he testified is standard in the industry and applies a fixed rate pressure to measure non-uniform fabric surfaces. (Id. at 580-81.) Dr. Bhat took magnified photographs of the test samples and opined that they showed swelling and charring when exposed to heat or flame and thus showed the classic signs of an intumescent. (Id. at 480-86, 564-65, 588, 605, 620.)

Dr. Bhat's first round tested SV-X41 on the accused fabrics. When challenged, Dr. Bhat acknowledged that these tests did not provide an accurate assessment because the coating could have interacted with the fabric. (Id. at 589).

Dr. Bhat's second round tested SV-X41 on a stainless steel pan. For these tests, Dr. Bhat used a coating of SV-X41 that was 1,250 to 1,720 microns thick, which Tietex claims is "many times thicker" than the amount Tietex actually applied to the accused fabrics under the patents-in-suit, thus rendering the results invalid. (Id. at 668-71.)

The third round tested the coating on an aluminum pan. These tests involved levels of SV-X41 between 633 and 1,000 microns, which Tietex contended were still multiples over the amount applied to its accused fabrics under the patents-in-suit. (Id. at 671-75.)

To respond to Tietex's contention that it actually applied, and the patents called for, coating at levels of approximately 50 to 100 microns, Dr. Bhat finally conducted tests on aluminum foil with SV-X41 in thicknesses ranging from approximately 50 to 250 microns. (Id. at 594-96, 603-04.) Dr. Bhat himself eventually reviewed microscopic cross-sectional photographs of Tietex's finished accused fabrics and opined that the thickness of the SV-X41 coating was somewhere between 150 to 250 microns. (Id. at 596, 600-03.)

PFG also relied on an email dated August 6, 2013, the day the first of these two lawsuits was filed, from Stephen Holland, president of Royal Adhesives, to Wade Wallace, president of Tietex. The email responded to a question from Wallace: "I need to know if our FR [flame retardant] chemistry would meet or not meet this specific definition of an 'intumescent system,' " according to a four-part definition of intumescent Wallace provided (which was also Tietex's proposed construction of the term prior to the court's Markman hearing). (Doc. 373-10 at 2.) In the email, Holland responded in part, "Our system behaves as an intumescent but does not exactly follow the definition below." (Id. ) The email then went on to explain the chemistry of the coating. (Id. )

PFG also presented the testimony of Walt Jones, its president, as to ownership of the patents. Ladson "Larry" Fraser, one of the inventors of the patents-in-suit, testified as to the benefits of PFG's flame-retardant bedding products. Doug Small, a PFG employee, testified to damages issues and to his observations of the thickness of Tietex's coatings. PFG presented testimony of Wallace via deposition about his having received the August 6, 2013 email from Holland. Finally, PFG presented a damages expert, Joel Wacek, whose testimony is not at issue in the post-trial motions.

At the close of PFG's evidence, Tietex moved for judgment as a matter of law (Tr. at 951), and the court took the motions under advisement (id. at 970).

Tietex presented the testimony of Martin Wildeman, its chairman and chief executive officer; Holland; and Richard Horrocks, Ph.D., its expert. Wildeman testified to the history of Tietex, the fact that the company had decided not to use intumescent coatings as far back as 2003 ( id. at 1002 ), and his observations of burn tests on Tietex's products using the patents-in-suit (describing them, without objection, as "totally different in my opinion to anything that I've seen relating to an intumescent") ( id. at 1003 ). He also explained that he owns over 30 patents, had read the patents-in-suit and concluded that Tietex was not practicing on them ( id. at 1005-06 ), and described his basis for that belief. Holland testified as to his explanation of his August 6, 2013 email to Wallace and his understanding of his company's SV-X41 product.

Finally, Tietex presented the testimony of Dr. Horrocks, who was qualified as an expert in the fields of flame retardant textiles, flame retardant coatings, including intumescent coatings, and the chemistry of flame retardants and intumescents. (Id. at 1089.) Dr. Horrocks is listed on the patents-in-suit as a holder of a patent that is prior art, and the patents-in-suit cite six publications that he authored or co-authored. (Id. at 1287-88; Doc. 152 at 20-21.)

Dr. Horrocks offered two primary opinions with respect to infringement. First, he testified that, based on his training, education, and experience, the chemical composition of SV-X41 would not cause it to swell when exposed to heat or flame, in part because it contains alumina trihydrate and lacks the necessary carbonific to swell. (Tr. at 1153-59, 1103, 1187.) Rather, he explained, the chemical composition is "flame retardant chemistry" designed to "releas[e] water vapor, which will extinguish, snuff out flame." (Id. at 1158.) In this regard, he claimed, the SV-X41 coating functions differently from an intumescent coating. (Id. ) Second, he testified that his testing on the coating, conducted on an inert glass fiber substrate using applications of SV-X41 in an amount he calculated as being called for in the patents-in-suit, established that the coating did not swell upon exposure to heat or flame. Unlike Dr. Bhat, who used an electronic pressure foot, Dr. Horrocks used a hand-manipulated electronic micrometer to conduct his measurements.

Dr. Horrocks offered several criticisms of Dr. Bhat's testing. With regard to each test, Dr. Horrocks noted that Dr. Bhat failed to report his results with any experimental error. (Id. at 1142-43.) As to Dr. Bhat's first test conducted on the accused fabrics themselves, Dr. Horrocks faulted the substrate as not being inert, noting that the coating would react with the underlying textile fabric. (Id. at 1142.) As to the testing on aluminum pans, Dr. Horrocks acknowledged that the photographs introduced at trial showed swelling (id. at 1199), but he attributed the result, as well as Dr. Bhat's testing on steel pans, to Dr. Bhat's use of an excessive thickness of the SV-X41 coating in the second and third tests, noting that the samples had a thickness in excess of fifteen times the thickness of the actual coating. (Id. at 1142-43.)

As for Dr. Bhat's fourth test conducted on aluminum foil, Dr. Horrocks acknowledged that at least one of the samples corresponded with the appropriate thickness of the coating on the accused fabrics. (Id. at 1144.) Drawing from his knowledge of chemistry and review of Dr. Bhat's expert report, however, he testified that aluminum foil is not an inert substrate and would react with the chemical components of SV-X41 when exposed to heat or flame.

(Id. at 1144, 1151-53, 1197-99, 1206-08.) Dr. Horrocks testified that he analyzed the microscopic photographs of the samples and observed a gray layer between the substrate and the coating, which he determined provided evidence of the reaction. (Id. at 1208-10.) He further testified that he had conducted measurements using the microscopic photos that indicated that the aluminum foil substrate had decreased in thickness after exposure to heat and flame. (Id. at 1211-12.) Dr. Horrocks testified that he could not determine whether the swelling was attributable to the coating and offered no opinion regarding the quantum of swelling attributable to the reaction between the SV-X41 and the aluminum foil substrate. (Id. at 1152.)

PFG presented rebuttal evidence from Dr. Bhat, challenging Dr. Horrocks's use of a glass fiber substrate for testing, opining that it was not inert. Dr. Bhat also testified that based on his examination of the SV-X41 coating, he concluded it was 150 to 250 microns thick, and he defended his calculation of error for his testing. (Id. at 1308-14.) Plaintiff also called Jones to deny that he broke any promise to Wildeman not to sue Tietex for infringement.

At the conclusion of its rebuttal case, PFG moved for judgment as a matter of law on literal infringement, infringement under the doctrine of equivalents, and willful infringement pursuant to Federal Rule of Civil Procedure 50(a). (Id. at 1332.) The court reserved ruling on PFG's motions. (Id. at 1333, 1351.)

After five days of trial, the jury returned a verdict of non-infringement of the patents-in-suit. (Doc. 350.)

Pursuant to Rule 50(b), PFG now renews its motion for judgment as a matter of law on the issues of literal infringement, infringement under the doctrine of equivalents, and willful infringement. (Doc. 372.) PFG also moves in the alternative for a new trial under Rule 59 of the Federal Rules of Civil Procedure. (Id. ); see Fed. R. Civ. P. 50(b). The motions are fully briefed and are ready for resolution.

II. MOTION FOR JUDGMENT AS A MATTER OF LAW

A. Standard of Review

"A determination of infringement is a question of fact, reviewed for substantial evidence when tried to a jury." Verizon Servs. Corp. v. Cox Fibernet Va., Inc., 602 F.3d 1325, 1340 (Fed. Cir. 2010) (citing Lucent Techs., Inc. v. Gateway, Inc., 580 F.3d 1301, 1309 (Fed. Cir. 2009) ). In a patent infringement action, the law of the regional circuit applies to a motion for judgment as a matter of law or a motion for a new trial. Id. at 1331. "Entry of judgment as a matter of law is appropriate only if the evidence is legally insufficient to support the jury's verdict." Bresler v. Wilmington Tr. Co., 855 F.3d 178, 196 (4th Cir. 2017) (citing Dennis v. Columbia Colleton Med. Ctr., Inc., 290 F.3d 639, 645 (4th Cir. 2002) ). The court must determine "whether there was a legally sufficient evidentiary basis for a reasonable jury, viewing the evidence in the light most favorable to the prevailing party, to find for that party." King v. McMillan, 594 F.3d 301, 312 (4th Cir. 2010) (quoting ABT Bldg. Prods. Corp. v. Nat'l Union Fire Ins. Co. of Pittsburgh, 472 F.3d 99, 113 (4th Cir. 2006) ). The grant of judgment as a matter of law is improper "[i]f reasonable minds could differ about the verdict." Id. (quoting ABT Bldg. Prods. Corp., 472 F.3d at 113 ). When ruling on a motion for judgment as a matter of law, "the district court is fully empowered to reverse its evidentiary rulings post-trial and to reconsider that evidence's effect on the trial." Conner v. Schrader-Bridgeport Int'l, Inc., 227 F.3d 179, 194 (4th Cir. 2000) (citing Weisgram v. Marley Co., 528 U.S. 440, 453-54, 120 S.Ct. 1011, 145 L.Ed.2d 958 (2000) ).

A party seeking judgment as a matter of law who also bears the burden of proof faces a formidable burden. Gilliam v. Montgomery Ward & Co., Inc., No. 96-1210, 1997 WL 429454, at *8 (4th Cir. 1997) (noting judgment as a matter of law should be granted in favor of the party bearing the burden of proof only in "extreme cases," citing 9A Charles Alan Wright & Arthur R. Miller, Federal Practice & Procedure: Civil § 2535 (2d ed. 1995) ). The court must determine whether "the effect of the evidence is not only sufficient to meet his burden of proof, but is overwhelming, leaving no room for the jury to draw significant inferences in favor of the other party." Radtke v. Lifecare Mgmt. Partners, 795 F.3d 159, 165-66 (D.C. Cir. 2015) (quoting Gay v. Petsock, 917 F.2d 768, 771 (3d Cir. 1990) ); Southern v. Agricraft Co., Inc., No. 89-2437, 1990 WL 133114, at *1 (4th Cir. 1990) ("When reviewing an order granting judgment n.o.v. to a party having the burden of proof, the standard to be applied is whether the evidence is 'so overwhelming that [the court] cannot uphold the jury's rejection of that defense.' " (quoting Thornhill v. Donnkenny, Inc., 823 F.2d 782, 786 (4th Cir. 1987) ).

B. Literal Infringement

PFG contends that it is entitled to judgment as a matter of law as to literal infringement because, based on the evidence presented at trial, no reasonable jury could find that SV-X41 does not swell upon exposure to heat or flame. (Doc. 373 at 3.) PFG's arguments can be grouped into the following general categories: (1) PFG's evidence established that SV-X41 swells when exposed to heat or flame, entitling PFG to judgment in its favor; (2) Tietex's evidence improperly redefined the court's claim construction for "intumescent"; (3) testimony of Holland, president of Royal Adhesives, the maker of SV-X41, constituted improper lay opinion; and (4) certain of Dr. Horrocks's opinions were unreliable and untested. Tietex responds that irrespective of Dr. Horrocks's opinions, (1) the jury was free to reject Dr. Bhat's opinions claiming to measure swelling in his testing; (2) Tietex did not redefine the court's construction of "intumescent"; (3) Tietex's examination of Holland was proper because PFG put his email into evidence and opened the door to examination of it, which nevertheless remained within the contours of the court's claim construction; and (4) Dr. Horrocks's testimony was proper. In sum, Tietex contends that PFG fails to demonstrate that its evidence of infringement was so overwhelming that a reasonable jury could only find in its favor, even if the challenged evidence were excluded. Many of these issues overlap, as will the court's discussion of them, but the court will attempt to address each in turn.

1. PFG's Evidence and Dr. Bhat's Unrebutted Opinions

PFG notes that Dr. Bhat testified that he measured swelling to some degree in every one of his several test samples. (Doc. 373 at 3.) PFG contends that no reasonable jury "unaffected by irrelevant and prejudicial evidence and argument" could find otherwise. (Id. ) PFG also points to Holland's email that noted that SV-X41 "behaves as an intumescent" (id. at 4 (citing Doc. 373-10) ) and contends that Dr. Horrocks admitted at trial that Dr. Bhat's testing showed swelling. (Id. ) According to PFG, Tietex's evidence failed to overcome this conclusion. (Id. ) Tietex responds that PFG had the burden of proof and the jury was free to reject Dr. Bhat's opinions. (Doc. 376 at 7.) Moreover, it contends, Dr. Horrocks rebutted Dr. Bhat's conclusions, creating fact issues for the jury. (Id. at 8.)

As PFG bore the burden of proof on the question of literal infringement, to be entitled to judgment as a matter of law it must establish that the evidence was not only sufficient to meet this burden, but is "overwhelming, leaving no room for the jury to draw significant inferences in favor of the other party." Radtke, 795 F.3d at 165-66 (quoting Gay, 917 F.2d at 771 ). For the reasons noted below, PFG fails to do so.

Most notably, the jury was free to disbelieve Dr. Bhat's testimony, particularly based on Tietex's cross-examination of him. For example, Dr. Bhat conceded that the results of his first tests were not reliable because of the testing conditions. ( Tr. at 589.) Dr. Bhat also conceded that many of his tests involved applications of SV-X41 that were multiples over the amount he believed was contemplated by the patents. (Id. at 595-96.) Dr. Horrocks also provided several reasons to question Dr. Bhat's conclusions, leaving the jury free to question and reject Dr. Bhat's testing results. Principal among the deficiencies noted were the following: Dr. Bhat's alleged use of applications of SV-X41 that were significantly greater than the proper amount for testing and that the coating would behave differently based on the applied thickness (id. at 1116-18); use of improper substrates that were not inert but allegedly interacted with the coating to skew the results; and the chemical composition of SV-X41 that is not expected to swell.

Moreover, PFG's representation of Dr. Horrocks's alleged admission is not accurate. The cited testimony, which related only to Dr. Bhat's testing on aluminum pans, provided:

Q: Would you agree that under Dr. Bhat's experimental conditions that his testing showed swelling?

A: According to his photographs, yes. I agree.

(Id. at 1199.) Thus, Dr. Horrocks conceded only that Dr. Bhat's photographs showed swelling; he did not agree with the methodology used. Quite the opposite, Dr. Horrocks disputed that the experimental conditions employed by Dr. Bhat (who himself conceded he was far less experienced in the field of intumescents than Dr. Horrocks (id. at 667) ) were appropriate, especially as to the amount of coating he applied, and thus did not accept Dr. Bhat's conditions as correct. True, Dr. Horrocks offered no opinion as to whether a coating of SV-X41 in excess of 100 microns swelled upon exposure to heat or flame. (Id. at 1194 ("Q: And my question is, is it correct that in this case, if Tietex's coatings are thicker than a hundred microns, you have no opinions; is that correct? A: I have no opinion if they're over a hundred microns.").) But it was not Tietex's burden to establish the absence of swelling at any level; rather, it was PFG's burden to establish swelling at a proper level. These challenges therefore fall far short of constituting overwhelming evidence necessary to justify judgment in PFG's favor.

2. Claim Construction

As PFG urged, the court construed the claim term intumescent as "a substance that swells and chars upon exposure to heat or flame." (Doc. 57 at 20-21.) PFG contends that Tietex introduced evidence that limited and thus impermissibly redefined the court's claim construction, pointing at times to actual testimony. (Doc. 373 at 5-6.) Tietex responds that its evidence properly fell within the court's claim construction and the scope of the patent. (Doc. 376 at 18-20.)

PFG's first area of contention relates to testimony as to the visibility and size of any swelling. For example, PFG points to testimony by Tietex's CEO, Wildeman, that during the "early days" of its product development in approximately 2003, Tietex's burn testing of its products in its laboratory demonstrated "there was no visible swelling" (Tr. at 973), which contrasted with his experience of having observed "very significant swelling" that was "highly visible" during burn tests of other products. (Id. at 999-1004.) While PFG contends this limited the claim construction, this testimony actually related to Tietex's defense of PFG's claim of willfulness. In fact, based in part on this testimony, Wildeman, who holds some 30 patents of his own, concluded, without objection, that Tietex did not believe it was infringing the patents-in-suit. (Id. at 1004, 1006-07.)

PFG next points to portions of Dr. Horrocks's testimony. As to nearly all of the complained of testimony, however, when PFG objected, the court sustained PFG's objections. E.g., (Doc. 373 at 5-6 (citing Tr. at 1132-33 (sustaining objection to Dr. Horrocks's testimony that "we have to agree what is [an] acceptable level of swelling" and noting that his own patent had swelling "somewhere between 50 percent and a hundred percent"); Tr. at 1131-32 (sustaining objections to testimony regarding "swelling more than a little" and to a lengthy answer that included the terms swelling "more than a little"); Tr. at 1136 (sustaining objection to phrasing "significant swelling"); Tr. at 1205 (sustaining objection to testimony including the phrase "swells and chars more than a little"); Tr. at 1128-1129 (sustaining objection about his expectation that his testing would reveal a "heavy char" or "char formation of a swelling character" as non-responsive to the question seeking an explanation of his test protocols) ).) Plaintiffs never moved to strike any of this testimony or requested any limiting instruction. Thus, PFG cannot complain where its objections were sustained and the court precluded questioning based on it.

PFG also cites testimony by Wildeman relating to the presence or absence of carbon in the coatings, objecting to his testimony that a "large amount of carbon" is required to achieve an intumescent swell. (Doc. 373 at 5 (citing Tr. at 1001-1002 ).) Similarly, it cites Holland's testimony that "in an intumescent, you have a very high level of carbon that's added to the system[,] [a]nd when that burns it chars and it swells up," that his company's products (SV-X41) do not have any added carbon, and that burn tests of intumescents produce swelling "you actually see" and "can actually touch [ ] and feel." (Id. (citing Tr. at 1051, 1054).) However, like much of PFG's complained of evidence, this testimony was admitted without objection. Moreover, it was relevant insofar as a key component of Tietex's defense was its contention that the chemistry of SV-X41 prevented it from swelling like an intumescent.

PFG next cites testimony by Dr. Horrocks who, when asked if he knew what an intumescent is, responded: "An intumescent is a material which swells and chars to form a thermal barrier once it's been exposed to heat or flame." (Doc. 373 at 5 (citing Tr. at 1083 ).) PFG contends that the court permitted Tietex to add a limitation to the claim - that it form a thermal barrier. What PFG fails to note is that upon PFG's objection, the court reminded the jury of the court's definition of an intumescent to be applied for purposes of the case. (Tr. at 1083-84.) Moreover, PFG's own patents-in-suit state they provided flame retardancy by producing a thermal barrier to protect the underlying product. See (PFG Exh. 1 at 5 ( '639 patent describing the flame retardant mechanism in the fabric as "barrier chemistry that causes the fabric to char and swell when exposed to flame to provide an insulating thermal barrier"), Exh. 2 at 6 (identical language in the '162 patent ).) And more to the point, PFG itself introduced, through its direct examination of its company witness, Larry Fraser, the proposition that an intumescent in the patents-in-suit works by forming a thermal barrier:

Q: And what is an intumescent?

A: An intumescent is a material that swells and chars upon exposure to heat or flame.

Q: Just in general terms, how does an intumescent work?

A: Well, when an intumescent is - comes into contact with a - with extreme heat or flame, it swells and chars. It actually - it actually swells and chars and - make - into a flame-preventive-type barrier with the material it's used with. It helps the fabric become a thermal barrier.

Q: You said a thermal barrier?

A: Yes.

Q: And what do you mean by thermal barrier?

A: Thermal barrier is what would keep the insult or the attack of a flame or extreme heat from further damaging things on the other side of it.

( Tr. at 246-47 (emphasis added).) Under these circumstances, it is difficult to say that Dr. Horrocks misled the jury into redefining the claim construction.

PFG also points to a portion of Dr. Horrocks's testimony that it characterizes as modifying the claim to "require a particular 'thickness' " of the coating. (Doc. 373 at 5 (citing Tr. at 1113 ).) However, what PFG cites to is a question to Dr. Horrocks whether he was aware of whether Dr. Bhat had performed any calculations to determine whether the thickness of his coatings he tested were within the requirements of the patents-in-suit, to which Dr. Horrocks answered, "I'm not aware of that." (Tr. at 1113.) Immediately following that, Dr. Horrocks testified, without objection, to the results of his calculations to confirm the thickness of the coatings contemplated by the patents-in-suit for purposes of his testing. (Id. )

Frequently, both before and during trial, the court advised the parties that they could not attempt to add limitations to the claim that were not approved by the court. E.g., (Tr. at 630-33, 1055, 1097-98, 1101.) The court also instructed the jury more than once on the court's construction of the claim and that the jury was bound by it. E.g., (Tr. at 1083-84, 1415.) Based on the trial record, PFG's contentions that the cited testimony added an impermissible claim limitation lacks merit.

3. Testimony of Holland and Wildeman

PFG challenges a portion of testimony by Holland and Wildeman that it characterizes as improper lay opinion testimony that was irrelevant and prejudicial. (Doc. 373 at 7-9.) More specifically, PFG argues that testimony by Holland that his company's product, SV-X41, does not swell (Tr. at 1067-68) was unreliable because it was not supported by scientific evidence where he only tested the product on coated fabrics and does not know how to measure swelling. (Doc. 373 at 8.) PFG contends that Wildeman's statements as to his visual observations of the accused fabrics, rather than quantitative measurements, are unreliable and inadmissible for purposes of determining literal infringement. Tietex responds that Holland's testimony that SV-X41 does not swell upon exposure to heat or flame and is not an intumescent constitutes a sufficient evidentiary basis upon which a reasonable jury could find that PFG failed to carry its burden of proving literal infringement. (Doc. 376 at 22-23.) Tietex argues that Holland's lay opinion testimony was properly admitted as a direct response to PFG's introduction of Holland's August 6, 2013 email which opened the door to his testimony. (Id. at 22 n.8 (citing Tr. at 1046-47 ).) Tietex further argues that the jury could reach a reasonable conclusion that Tietex did not infringe based on Wildeman's testimony that he did not observe visible swelling of the SV-X41 coating when he observed burn tests. (Id. at 23.)

As to Holland, context is necessary. His testimony was the subject of significant discussion with the court. During Holland's direct examination, PFG's objection was initially on the ground of relevance. (Tr. at 1040.) PFG ultimately agreed with Tietex's assessment that Holland could testify as to "the bases for what he said there [in his August 6, 2013 email to Mr. Wallace] and if he changed his opinion on it." (Id. at 1041.) The court also found that by introducing the August 6, 2013 email, PFG had opened the door to Tietex's examination of Holland about the email. (Id. at 1046-47.) The court also noted that Holland could testify as to his perceptions as it related to a defense of the claim of willfulness and explained that, while it would consider the testimony on a question-by-question basis, it would sustain PFG's objections if Tietex's counsel strayed from these areas. (Id. at 1045-46, 1056-57.) Even in the absence of objection, the court interjected itself, sua sponte , to ensure that the testimony did not conflict with the court's claim construction. E.g., (Tr. 1054-56.) As to the limited testimony to which PFG now complains, PFG raised no objection at trial. Therefore, any objection has been waived. Further, to the extent PFG argues that Holland was not qualified to explain whether he believed his company's product was an intumescent, it opened the door to that testimony by introducing Holland's August 6, 2013 email on that very issue. (Tr. at 1041-46.)

As to Wildeman, PFG objects to what it describes generally, without record citation, to be testimony about his visual observations of the accused fabrics. (Doc. 373 at 7-8.) It contends that Wildeman's testimony was inadmissible lay opinion but acknowledges in its reply (citing to Tr. 1021-22, 1032) that it was admissible on the issue of willfulness. (Doc. 379 at 13.) This is just how the court limited his testimony.

When PFG raised the issue at trial, it argued that Wildeman should be precluded from testifying as to his visual observations of swelling because the court had earlier ruled that Dr. Horrocks was prevented from opining as to swelling of SV-X41 tested on steel pans based on his unaided, visual observation. (Tr. at 897-98.) The court drew a distinction between Dr. Horrocks's opinion offered for literal infringement (because it was ipse dixit ), and Wildeman's testimony offered to rebut willfulness. (Id. at 899.) The court stated it would proceed question by question and directed PFG to object if it concluded that any question strayed into an impermissible area. (Id. at 898-901.) PFG made but one objection about Wildeman's visual observations of fabric testing - on the ground of relevance, which was overruled. (Id. at 1000.) The testimony PFG actually complains of came in on cross-examination in response to questions by PFG's counsel, and PFG never moved to strike any part of any response it now claims is objectionable. However, because Wildeman's testimony was admitted as it related to Tietex's defense of PFG's claim of willful infringement, the court need not consider Tietex's attempt to rely on this testimony to support the merits of its literal infringement defense (see Doc. 379 at 13-14). (Doc. 376 at 23). Ultimately, the court expressed frustration over the absence of objections and remonstrated counsel on both sides that it was their duty to object and not to assume the court would do so sua sponte . (Tr. at 1032-33.)

On this record, PFG fails to establish entitlement to relief.

4. Admissibility of Dr. Horrocks's Testimony

The remainder of PFG's arguments relate to the testimony of Tietex's expert, Dr. Horrocks.

PFG first argues that any criticism regarding the thickness of the samples was irrelevant and inadmissible because it improperly added a limitation to the claim and was directly undermined by Dr. Horrocks's admission that Dr. Bhat's aluminum pan testing showed swelling. (Doc. 379 at 5.) PFG contends that Dr. Horrocks superimposed a thickness requirement on the court's claim construction, noting that the patents-in-suit have a separate claim limitation governing the amount of coating applied to the patented fabrics. (Doc. 373 at 6 n.1.) Tietex argues that "[i]t is axiomatic that, if the SV-X41 coating is not an 'intumescent' as it is actually applied on Tietex's fabrics, Tietex's fabrics would not be treated with an intumescent coating, and could not have been found to infringe PFG's patents." (Doc. 376 at 18-19 (emphasis omitted).) Tietex argues that "Dr. Horrocks's opinion and Tietex's criticism of Dr. Bhat simply recognizes that, if the SV-X41 coating does not meet the definition of an 'intumescent' at the thicknesses in which it is applied on Tietex's fabrics, those fabrics cannot infringe PFG's patents." (Id. at 19.)

Claim construction is a matter of law for the court to decide. Markman, 52 F.3d at 979. Once the court has construed a claim, the parties may not seek to contradict, or further construe, the court's claim construction to a jury. Exergen Corp. v. Wal-Mart Stores, Inc., 575 F.3d 1312, 1321 (Fed. Cir. 2009) ; Tinnus Enters., LLC v. Telebrands Corp., No. 6:16-CV-00033-RWS, 2017 WL 3457104, at *2-4 (E.D. Tex. Aug. 11, 2017).

Here, neither party challenges the court's construction of the claim term intumescent as "a substance that swells and chars upon exposure to heat or flame." (Doc. 57 at 20-21.) During trial, Dr. Horrocks raised a factual dispute regarding the appropriate method of testing whether the SV-X41 coating applied to the accused fabrics swells upon exposure to heat or flame. He opined that the coating would behave differently at different thicknesses (i.e., "thermally thin" versus "thermally thick"), testified that it was important to test the coating at the thickness actually contemplated by the patents-in-suit, and explained his testing at that level.

Dr. Horrocks's testimony did not impermissibly add limitations to the claim. At a minimum, it reflects a reasonable dispute over the appropriate method, scientifically, to test the SV-X41 to determine whether it, as called for in the patents-in-suit and thus as applied on the accused products, infringes PFG's patents. Dr. Horrocks based his opinion on his knowledge of the applicable science, the chemical composition of the SV-X41 coating, the amount of coating called for in the patents-in-suit, and his calculations of the amount of SV-X41 applied on the accused fabrics by Tietex. Based on these considerations, he testified that the SV-X41 coating applied on the accused products did not swell upon exposure to heat or flame. He also testified that testing the proper amount was critical because it is commonly known that too much of any substance, even though not an intumescent, could swell upon exposure to heat or flame. (Doc. 119-1 at 214-15 (observing during deposition that a thicker coating of nylon, which is not an intumescent, would swell and char when exposed to heat or flame).) To adopt PFG's position - to bar Dr. Horrocks from responding to an opposing expert's testing that employed amounts of SV-X41 at multiples over that ever contemplated by the patents-in-suit - would impermissibly extend the coverage of the patents-in-suit beyond the scope of the claim limitation. See Aqua-Aerobic Sys., Inc. v. Aerators Inc., 211 F.3d 1241, 1245 (Fed. Cir. 2000) (affirming the district court's rejection of the patentee's proposed claim construction that would broaden the claims beyond the scope of the claim limitations and specification description).

PFG next argues that Dr. Horrocks's testing is unreliable because it was not scientifically valid and, therefore, is inadmissible under Federal Rule of Evidence 702 and Daubert v. Merrell Dow Pharm., Inc., 509 U.S. 579, 113 S.Ct. 2786, 125 L.Ed.2d 469 (1993), and its progeny. (Doc. 379 at 7.) Relying on this court's prior order denying PFG's motion for partial summary judgment, Tietex contends that this court has already rejected PFG's arguments in considering the same evidence it introduced at trial. (Doc. 376 at 2-3, 11-17; see Doc. 152 at 22.) PFG responds that the court's prior motion does not conclusively resolve the issue and contends that the evidence presented at trial was different from that considered in PFG's prior motion. (Doc. 379 at 8-10.)

Under Rule 702, an expert witness is permitted to offer opinion testimony if he "is qualified as an expert by knowledge, skill, experience, training, or education." The witness's knowledge must help the trier of fact understand the evidence or determine a fact in issue, the testimony must be based on sufficient facts or data, the testimony must be the product of reliable principles and methods, and the witness must reliably apply the principles and methods to the facts of the case. Fed. R. Evid. 702(a)-(d). This rule "imposes a special obligation upon a trial judge to 'ensure that any and all [expert] testimony ... is not only relevant, but reliable.' " Kumho Tire Co. v. Carmichael, 526 U.S. 137, 147, 119 S.Ct. 1167, 143 L.Ed.2d 238 (1999) (quoting Daubert, 509 U.S. at 589, 113 S.Ct. 2786 ).

Under Rule 702, expert testimony is admissible if it "rests on a reliable foundation and is relevant." E.E.O.C. v. Freeman, 778 F.3d 463, 466 (4th Cir. 2015) (quoting Westberry v. Gislaved Gummi AB, 178 F.3d 257, 260 (4th Cir. 1999) ). The overall focus is on scientific validity, based on the principles and methods used. Daubert, 509 U.S. at 592-93, 113 S.Ct. 2786. Thus, the court must "ensure that the proffered expert opinion is 'based on scientific, technical, or other specialized knowledge and not on belief or speculation, and inferences must be derived using scientific or other valid methods.' " Nease v. Ford Motor Co., 848 F.3d 219, 229 (4th Cir. 2017) (quoting Oglesby v. Gen. Motors Corp., 190 F.3d 244, 250 (4th Cir. 1999) ). The district court has "broad latitude" to take into account any "factors bearing on validity that the court finds to be useful." Freeman, 778 F.3d at 466 (quoting Westberry, 178 F.3d at 261 ). The court makes its determination under Federal Rule of Evidence 104(a), assessing whether the preponderance of the evidence demonstrates the admissibility of the evidence under Rule 702's standards. Daubert, 509 U.S. at 592-93 & n.10, 113 S.Ct. 2786. If that is met, questions as to the weight of the evidence are for the factfinder to resolve under Rule 104(b).

At the outset, it bears noting that the court entertained an extensive pretrial challenge to Dr. Horrocks's opinion testimony and issued a detailed analysis, which granted the motion in part and denied it in part. (Doc. 152.) To a large extent, PFG's challenges seek to re-litigate those issues. The court also notes that PFG does not challenge Dr. Horrocks's qualifications to offer any opinion at issue. Indeed, Dr. Horrocks is listed in the patents-in-suit as a holder of a patent that is prior art, and the patents-in-suit favorably cite six publications he authored or co-authored. (Tr. at 1087-89; Doc. 152 at 20-21.) Moreover, PFG's expert, Dr. Bhat, conceded that Dr. Horrocks had more experience in the field of intumescents. ( Tr. at 667.)

PFG contends that the evidence presented at trial supports several arguments as to why Dr. Horrocks's testing is unreliable and therefore inadmissible.

First, PFG contends that Dr. Horrocks's calculation of the coating thickness on the accused products was unreliable. (Doc. 379 at 6.) It cites Dr. Horrocks's acknowledgment that he never inquired of Tietex as to the thickness of the coating on its fabrics and never personally examined the fabrics to determine it. (Id. ) PFG further represents that Dr. Horrocks conceded it would have been more accurate to ascertain the thickness by examining the actual fabrics under a microscope, which he did not do. (Id. (citing Tr. at 1192-93 ).)

Dr. Horrocks testified that he determined the thickness of Tietex's coating based on his prior experience working with similar fabrics, flame retardants, and intumescent coatings. (Tr. at 1109- 10, 1116-18.) He also testified that he performed an analysis and determined that the coating used on Tietex's fabrics was 25 to 53 microns thick. (Id. at 1113.) As to whether he could have observed the coating on the Tietex fabrics under a microscope, Dr. Horrocks stated that it would not have been feasible to do so because the coating permeates the fabric, thus attempting to distinguish a contrary response in his deposition. (Id. at 1191, 1193 ("So if this [deposition answer] is relating to the fabric samples I produced, then it is a feasible way of determining the thickness because you don't get the penetration here that you do on a Tietex fabric. So we have to understand the context you asked that question and the context of the answer I gave you.").) Dr. Horrocks did allow that he could have used a microscope to determine the coating thickness on the glass woven fabrics used in his testing, rather than the accused fabrics. (Id. at 1193 ("Q: And is it correct that based on the answer that you gave me, that that was all something you could have done? A: I could have done with the experimental fabrics I had.") ) In the end, PFG does not directly dispute calculations performed by Dr. Horrocks or otherwise argue that he lacked the relevant qualifications or expertise to perform such calculations, relying instead on the analysis of its expert, Dr. Bhat. So, while this criticism affects Dr. Horrocks's credibility, it does not render his testimony inadmissible. See Syngenta Crop Protection, LLC v. Willowood Azoxystrobin, LLC, 267 F.Supp.3d 649, 655 (M.D.N.C. 2017) (noting that " Daubert and Rule 702 are safeguards against unreliable or irrelevant opinions, not guarantees of correctness[,]" and that "the fact finder, not the court, must determine whether an expert is credible and whether the expert's opinions are correct." (quoting i4i Ltd. P'ship v. Microsoft Corp., 598 F.3d 831, 854 (Fed. Cir. 2010), aff'd, 564 U.S. 91, 131 S.Ct. 2238, 180 L.Ed.2d 131 (2011) ) ).

Second, PFG relies on Dr. Horrocks's testimony that in a previous study he had determined that a glass woven fabric "was not as inert as anticipated." (Doc. 373 at 11; Doc. 379 at 6.) Dr. Bhat also testified in rebuttal, relying at least in part on this prior study by Dr. Horrocks, that the "E-glass" substrate Dr. Horrocks used was not inert. (Tr. at 1310.) Dr. Horrocks testified that his glass fabric was inert (Id. at 1121-22) and that the chemical composition of the intumescents in that study differed significantly from SV-X41 and thus this prior study could not serve as a proper basis to predict how the glass fabric would react. (Id. at 1204 ("So you cannot compare the results of what I did 20 years ago for a particular situation with what I have done here when the situation is completely different.").) Thus, this was a disputed fact issue. Moreover, even if the glass fibers he used were not fully inert, there is no showing how their use would have rendered Dr. Horrocks's opinion unreliable. As such, this criticism goes to the weight rather than the admissibility of Dr. Horrocks's testing. See United States v. Baller, 519 F.2d 463, 466 (4th Cir. 1975) ("Unless an exaggerated popular opinion of the accuracy of a particular technique makes its use prejudicial or likely to mislead the jury, it is better to admit relevant scientific evidence in the same manner as other expert testimony and allow its weight to be attacked by cross-examination and refutation.").

Third, PFG raises several issues with regard to Dr. Horrocks's testing methods. It notes that Dr. Horrocks designed his test protocol for this litigation and never used it previously. (Doc. 373 at 12; Doc. 379 at 7 (citing Tr. at 1175 ).) It further notes that he admitted he had never used a caliper to measure intumescent materials and contends that his testimony demonstrated that his measurements were unreliable. (Doc. 373 at 11; Doc. 379 at 7-8 (citing Tr. at 1172 ).) Further, PFG argues, Dr. Horrocks disregarded the variations in thickness on the glass fabric he used as a substrate and compared measurements from different locations as if the coated fabric was uniform. (Doc. 373 at 11-12; Doc. 379 at 7.) PFG also claims that Dr. Horrocks testified that he could have measured the same location before and after the testing, but did not. (Doc. 373 at 12; Doc. 379 at 7 (citing Tr. at 1185 ).) Finally, PFG contends that Dr. Horrocks admitted that his testing was incapable of detecting swelling of less than 22 percent, due to his calculated margin of error. (Doc. 373 at 11; Doc. 379 at 7 (citing Tr. at 1186 ).)

One consideration in determining admissibility is "whether experts are testifying 'about matters growing naturally' out of their own independent research, or if 'they have developed their opinions expressly for purposes of testifying.' " Wendell v. GlaxoSmithKline LLC, 858 F.3d 1227, 1232 (9th Cir. 2017) (quoting Daubert v. Merrell Dow Pharm., Inc., 43 F.3d 1311, 1317 (9th Cir. 1995) ). "While independent research into the topic at issue is helpful to establish reliability, its absence does not mean the experts' methods were unreliable." Id. at 1235. Here, PFG's criticism that Dr. Horrocks developed this test for this litigation carries little persuasiveness where PFG's own expert acknowledged that there was no established industry test to measure swelling in intumescents. ( Tr. at 663-64 ); see Wendell, 858 F.3d at 1235 (noting that "expert testimony may still be reliable and admissible without peer review and publication," particularly "when dealing with rare diseases that do not impel published studies").

This court previously found that Dr. Horrocks's testing methods are well supported within the relevant scientific community. See, e.g., (Doc. 152 at 17 ("Whatever the criticisms of Horrocks' techniques in performing his measurements, it is clear that his methods of testing flame-retardant fabrics have been peer-reviewed and published approximately 200 times.").) At trial, Dr. Horrocks opined that there was no established test protocol within the industry for determining whether a coating swelled. (Tr. at 1105.) On this point, Dr. Bhat agreed. (Id. at 663-64.) Dr. Horrocks outlined three considerations he identified in designing and performing his test on the coating. (Id. at 1106.)

First, he considered the proper thickness of the coating, opining that it was important to test the coating at the thickness as applied to the allegedly infringing fabric, which he determined to be approximately 25 to 53 microns, as noted above. Drawing from his extensive experience in flame retardant chemistry, he testified that the coating would function as a "thermally thin" material at a thickness of 50 microns and "would behave quite differently" from thicker applications. (Id. at 1117-18.)

Second, Dr. Horrocks testified that he analyzed the appropriate substrate on which to test the coating, noting that it must be inert so as not to react with the coating when exposed to heat or flame and thus render the measurement of swelling unreliable. (Id. at 1119.) Based on this consideration, he chose to perform the experiment on a glass woven fabric, which he contended would mimic the textile surface of the accused fabrics while providing an inert surface. (Id. at 1118-23.)

Third, he considered the proper testing protocol and procedures. (Id. at 1123-26.) He selected a hand-adjustable electronic micrometer (also referred to as a caliper) to measure the coating because the glass fabric was a hard surface. (Id. at 1123.) He explained his prior experience using this measurement tool and believed it was appropriate based on the potential increases in thickness that he would have expected with an intumescent coating. (Id. at 1133-35.) He testified that it was a device a person of ordinary skill in the art would have found acceptable in this application and noted that he rejected the pressure foot used by Dr. Bhat because, he claimed, it was too large to measure the small areas at issue and because a caliper was, in his view, more reliable for this application. (Id. at 1180-82.) Dr. Horrocks also responded to Dr. Bhat's "valid criticism" that the design of his testing with an electronic caliper did not permit him to measure the coating thickness in the same area before and after application of heat and flame. (Id. at 1130, 1182.) According to Dr. Horrocks, had he measured the thickness first, he would have had to cut the sample, which would have destroyed it and compromised the accuracy of the measurement. (Id. at 1130.) Finally, he highlighted the importance of determining experimental error and discussed his calculation and use of experimental error. (Id. at 1126, 1139-41.)

PFG challenges Dr. Horrocks's use of an electronic caliper purchased approximately fifteen years ago from a company specializing in selling equipment for hand loading ammunition and which he stored in a non-climate-controlled garage in the summer months. (Doc. 373 at 11 (citing Tr. at 1171-72 ).) Dr. Horrocks testified that he was highly proficient in using a caliper and was "confident that [he] could get the maximum accuracy out of the measurements that [he] was using." (Tr. at 1133-34.) He further disputed Dr. Bhat's testimony that calipers were not used to measure fabrics and testified that this method of measurement was acceptable to an expert in the relevant field. (Id. at 1134-35.)

The court addressed challenges to the use of the electronic caliper in its earlier opinion. In particular, the court noted that according to Dr. Horrocks, a thumb wheel micrometer is highly sensitive, using a digital readout measuring increments of 2.5 microns - that is, one tenth of one thousandth of an inch - and is sufficiently objective for his purposes to conduct such miniscule measurements. (Doc. 152 at 15.) Dr. Horrocks contested PFG's claim that the fact the handwheel must be manipulated by hand rendered it too unreliable. (Id. ) Rather, in one of his depositions, Dr. Horrocks testified that the micrometer can be reliably operated on the surfaces at issue with "quite reproducible" results and for present purposes the caliper was more reliable than the pressure foot used by Dr. Bhat because, Dr. Horrocks contended, the pressure foot was too large to adequately measure the areas being tested. (Id. at 15-16.) Dr. Horrocks had concluded that the slight variability of results was inherent in the ordinary application of the instrument and the swelling of the material itself. (Id. at 15-17.)

The court allowed that PFG's criticisms about the use of the micrometer were valid. (Id. at 17.) No doubt, the fact that the instrument is hand-manipulated interjects an element of subjectivity into the measuring process. But a micrometer is a scientific instrument used for measuring, and it is accurate to the nearest 2.5 microns, which is an extremely small unit of measure. Here, Dr. Horrocks testified it was calibrated to within 10 microns. (Tr. at 1132-33.) Dr. Horrocks's measurements using this device could have been tested and either reproduced or challenged by Dr. Bhat, had he wished to do so. While Dr. Bhat offered his own testing and results, he did not attempt to replicate Dr. Horrocks's testing on a glass substrate and measure the results using the pressure foot. See (Doc. 151-1 at 5-6 (acknowledging Dr. Horrocks's testing but declining to conduct his own on the fiberglass fabric); Doc. 319; Tr. at 606, 612-13.) At trial, Dr. Horrocks again explained his use of the caliper and opined, without objection, that a person of ordinary skill in the art would find it acceptable. (Tr. at 1135.)

Under these circumstances, especially where Dr. Horrocks has a criticism that the pressure foot was too large to accurately test the area at issue, PFG has not demonstrated a basis to reverse the court's previous ruling denying PFG's motion to exclude Dr. Horrocks's opinion testimony for a jury's consideration. (Doc. 152 at 14-15, 22 (finding that, as long as the methods have scientific validity and are reliable, the accuracy of his method of measurement using a caliper goes to the weight of the testimony rather than its admissibility) ); see Heller v. Shaw, Inc., 167 F.3d 146, 160 (3d Cir. 1999) (holding that expert testimony cannot be excluded simply because the expert uses one test rather than another, when both tests are accepted in the field and both reach reliable results).

Dr. Horrocks testified that he accounted for the variations in thickness as well as the potential for human error by calculating experimental error. He stated that because the uncoated glass fiber had natural undulations, he conducted several measurements of it and determined that on average its thickness was .30 millimeters, with a deviation of ± 20 microns. (Tr. at 1174-75.) He then applied a 45-micron layer of SV-X41 coating to this substrate. (Id. at 1177.) This produced an uneven surface. (Id. at 1178.) After exposure to heat and flame, he cut the samples and measured the thickness on various places of the exposed coating. (Id. at 1178-79.) He measured the deviations on the exposed coating, which he termed his error rate, of ± 20 microns. (Id. at 1185.) He concluded that the measurements of the exposed coating fell within his deviations noted on the unexposed coating; in other words, he found no swelling within his rate of error of 22 percent. (Id. at 1131, 1135-36, 1186.) Dr. Horrocks acknowledged that he "cannot say there was zero swelling because there's always uncertainty in any measurement." (Id. at 1131.) But he did testify, without objection, that he expected to see swelling of 70 or 80 microns, which he did not observe. (Id. at 1133.) He concluded that, based on his knowledge of intumescents, his measurements, and the swelling he would have expected to see, there was no scientifically significant swelling (or increase in thickness) in his test results. (Id. at 1136.)

While Dr. Bhat criticized the rate of experimental error, he did not dispute Dr. Horrocks's calculation of it. (Id. at 712-13.) In fact, Dr. Bhat conceded that if Dr. Horrocks's calculations of his rate of error were correct, then Dr. Horrocks was correct that his test results were the statistical equivalent of no swelling. (Id. at 712-13.) This would be sufficient for a jury, if believed, to conclude that the SV-X41 applied during the testing did not swell.

As this court previously found, Dr. Horrocks's calculated rate of error was sufficient to survive the admissibility requirements of Rule 702. (Doc. 152 at 20 (finding that Dr. Horrocks's calculated rate of error met the third factor under Daubert ) ); see Banks v. United States, 75 Fed.Cl. 294, 301 (2007) (holding that "[t]he potential rate of error need not be completely accurate," but based on sufficient evidence, and any disagreement with the expert's calculated rate of error may be raised during trial and presented on cross examination). Moreover, PFG's expert did not dispute his calculation. The question is whether Dr. Horrocks's opinions he draws from his calculations are reasonably drawn from his methods and principles. Dr. Bhat concluded that the experimental error was "too high an experimental error to trying [sic] to determine the small change in difference." (Tr. at 713.) But Dr. Horrocks did make clear the limits of his testing: that it showed no swelling within the limits of his experimental error rate and that he "cannot say there was zero swelling because there's always uncertainty in any measurement." (Id. at 1131.) Dr. Horrocks opined that this was the equivalent of no swelling, given his knowledge of how intumescents behave, noting that any error in his calculations would not have been the result of intumescent swelling. (Id. at 1131, 1133-36.)

Fourth, PFG contends that Dr. Horrocks's aluminum foil reactivity theory is "entirely unreliable," irrelevant, and unsupported by sufficient facts. (Doc. 373 at 13). At trial, Dr. Horrocks limited his opinion to the criticisms of Dr. Bhat's use of an aluminum substrate and offered no opinion as to the quantum of swelling associated with any purported reaction between SV-X41 and the aluminum foil substrate. (Tr. at 1151-52.) The court previously considered and denied PFG's motion to exclude Dr. Horrocks's aluminum opinions insofar as they describe criticisms of the aluminum foil substrate used in Bhat's supplemental testing. (Doc. 318 at 36.) As the court previously noted, "Dr. Horrocks's opinions regarding the general chemical principles and reactivity of aluminum is well supported by scientific literature." (Id. at 34.) PFG offers no persuasive evidence that such testimony is inadmissible. See (Id. at 36.)

Finally, PFG contends that Dr. Horrocks failed to support his "thermally thin/thermally thick opinion with any testable reliable science" or testing regarding the thermal thickness boundary of SV-X41. (Doc. 379 at 10; see Doc. 373 at 9-10.) Furthermore, it argues that Dr. Horrocks failed to provide testimony regarding any standards, methodology, or support within the scientific literature to support this theory and failed to apply any such analysis to the coating at issue. (Doc. 379 at 11.) Dr. Horrocks offered his opinions based on his substantial knowledge of flame retardant materials. See (Doc. 152 at 10 (noting that Dr. Horrocks's curriculum vitae lists previous peer-reviewed publications he has authored on thermally thin coatings).) As Dr. Horrocks acknowledged, "a scientist will carry out experiments, and you'll say for this sort of material, that's thermally thin, and for another one, it's thermally thick and there's a boundary between the two." (Tr. at 1117.) PFG overlooks the fact that Dr. Horrocks did in fact perform a test using what he determined to be a thermally thin coating of SV-X41 with a thickness of 50 microns. (Id. at 1113, 1118.) In the final analysis, whether or not the coating of SV-X41 is thermally thin or where the line between thermal thinness and thickness lies does not undermine Dr. Horrocks's opinions; his testing provided support for his opinion that SV-X41 was applied at a thickness of approximately 50 microns and that he observed no measurable swelling. In sum, Dr. Horrocks's opinion testimony satisfied the preponderance of the evidence standard to be admissible. While the case presented unique questions and Dr. Horrocks's testing methods differed from those of Dr. Bhat, the weight of the differences goes to their credibility - a consideration quintessentially within the role of the jury. "Vigorous cross-examination, presentation of contrary evidence, and careful instruction on the burden of proof are the tradi