Optically Brightened Laminating Epoxy

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BRT is an optically brightened version of our CLR system, for white surfboard lamination and hot coating. Make Things Better® on your next project with this Super Sap® Formulation.

30% Biobased Content

USDA BioPreferred Certified

Product Overview

BRT Optically Brightened Laminating Epoxy is a Super Sap® Formulation. This optically-brightened, clear laminating system is designed specifically for ultra-white cosmetic applications, such as surfboard laminations over EPS (polystyrene) or PU (polyurethane) foam. Based on Entropy Resins classic CLR – CLEAR Epoxy Resin, BRT Optically Brightened Laminating Epoxy Resin can be paired with all CLR Clear hardeners.

Available in EXTRA FAST (CLX Extra Fast Hardener), FAST (CLF Clear Fast Hardener), and SLOW (CLS Clear Slow Hardener) cure speeds. Hardener speeds can be combined to custom working times.

Extra Fast Cure: 18 min pot life, 2 HR tack-free time.

Fast Cure: 21 min pot life, 4 HR tack-free time.

Slow Cure: 43 min pot life, 8 HR tack-free time.
Two-part epoxy resin kits are comprised of BRT Optically Brightened Laminating Epoxy Resin and CLX Clear Extra Fast Hardener, CLF Clear Fast Hardener, or CLS Clear Slow Hardener.
For dark color substrate applications, we recommend our CLR formula.

Best Uses

  • White Surfboards

Prop 65

Click to view all Entropy Resins California Prop 65 statements.


Application Tips:
  • For best results, measure the two components by weight within 5% of the recommended mix ratio.
  • Always mix product for at least two minutes, scraping the container to ensure complete mixing.
  • Use products in a controlled environment. Avoid high humidity and cold temperatures.
  • Amine blush, a by-product of the curing process, appears as a wax-like film cured epoxy and is more noticeable in cool, moist conditions. It can clog sandpaper and inhibit subsequent bonding.
  • Blush is water-soluble and easily removed with clean water (not solvent) and an abrasive pad.
  • For good adhesion, epoxy bonding surfaces should be clean, dry, and sanded.
  • If unfamiliar with the product, create smaller test samples before starting a larger-scale project.


For general epoxy handling instructions, visit Epoxy Basics

For detailed instructions on fiberglass application, visit Applying Fiberglass.

For detailed instructions on coating, visit Clear or Seal Coating.

For detailed instructions on preventing bubbles in epoxy coatings, visit Bubble-free Coating & Casting.

For detailed instructions on hot-coating, visit Hot Coating Surfboards.

For tips on handling epoxy safely, visit Epoxy Safety.



BRT - Technical Data Sheet

Mechanical Data
CLX Extra Fast
CLF Fast
CLS Slow
Tensile Modulus (ASTM D638) 450,000 psi (3.1 GPa) 444,000 psi (3.0 GPa) 468,000 psi (3.2 GPa)
Tensile Strength (ASTM D638) 9,500 psi (65.5 MPa) 9,500 psi (65.5 MPa) 9,800 psi (67.6 MPa)
Elongation (ASTM D638) 6% 5% 6%
Flexural Modulus (ASTM D790) 440,000 psi (3.0GPa) 440,000 psi (3.0GPa) 430,000 psi (3.0 GPa)
Flexural Strength (ASTM D790) 14,000 psi (96.5 MPa) 13,500 psi (93.1 MPa) 14,580 psi (100.5 MPa)
Compression Strength (ASTM D695) 11,330 psi (78.1 MPa) 11,330 psi (78.1 MPa) 12,520 psi (86.3 MPa)
Tg Ultimate (DSC, midpoint) 145°F/63°C 133°F/56°C 135°F/57°C
Hardness (Shore D) 70-80 70-80 70-80
Processing Data
CLX Extra Fast
CLF Fast
CLS Slow
Mix Ratio (by volume) 2:1 2:1 2:1
Mix Ratio (by weight) 100:43 100:44 100:43
Viscosity (A/B/Mixed @ 77°F/25°C) 2040/180/1160 2040/280/1100 2040/140/800
Component Density  (specific density @ 77°F/25°C) 1.14 (resin), 0.98 (hardener) 1.14 (resin), 0.98 (hardener) 1.14 (resin), 0.98 (hardener)
Mixed Density (specific density @ 77°F/25°C) 1.09 1.1 1.09
Pot Life (specific density @ 77°F/25°C) 18 Min 21 Min 43 Min
Tack Free Time (@ 95°F/35°C) 2 hrs 4 hrs 8 hrs
Recommended Full Cure 7 days @ 77°F/25°C 7 days @ 77°F/25°C — Post Cure Recommended 7 days @ 77°F/25°C — Post Cure Recommended
Environmental Data
CLX Extra Fast
CLF Fast
CLS Slow
VOC Content (ASTM D2369) 0.16 lbs/gal (19.5 g/L) 0.26 lbs/gal (31.5 g/L) 0.00 lbs/gal (0.00 g/L)
Mixed Biobased Carbon Content (ASTM D6866) 20% 20% 21%

This technical information is provided in good faith and is based on the best knowledge of Gougeon Brothers, Inc. We cannot guarantee this data because conditions of product use are beyond our control.


Downloadable Product Safety Data Sheets are listed below. For general epoxy safety tips, visit our Epoxy Safety page.


Online orders ship UPS Ground with domestic delivery within 3 to 5 days, Canada 5-7 days.

Customer Service

For questions about existing orders please email: [email protected]

For questions about our products or technical advice call: 310-882-2120

Bulk / International Orders

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