Entropy Clear Slow Hardener, CLS
Entropy Resins Entropy Resins
  • Entropy Clear Slow Hardener, CLS
  • Entropy Clear Slow Hardener project, CLS

Entropy Clear Slow Hardener

Entropy Clear Slow Hardener (CLS) is used to extend working properties and cure time when mixed with Entropy Clear Laminating Epoxy Resin (CLR) or Optically Brightened Laminating Epoxy Resin (BRT) for laminating wood, fiberglass, carbon fiber, or Kevlar. These premium resins are used for hand layup, room-temperature processes, or infusion laminating.

This biobased resin system exhibits low color, excellent air release, and exceptional UV and color stability. Use with CLR resin or BRT resin for long pot life and low exotherm lamination and coatings. Resin and hardener combined have a bio-content greater than 30%, and can be modified with epoxy compatible colorants and fillers.

Requires corresponding size of Clear Laminating Epoxy Resin (CLR) or Optically Brightened Laminating Epoxy Resin (BRT - bright white) for use (2:1 mix ratio). See chart below.

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$37.36 / ea
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Tech Spec Product Info User Generated Content

Features of Clear Slow Hardener (CLS) Combined with CLR Resin or BRT Resin

  • Slow hardener for Entropy's high-performance, CLR clear epoxy resin, or bright white BRT epoxy resin.
  • Green epoxy resin with longer pot life and a slower room temperature cure than CLF (fast) or CLX (Extra Fast) hardeners.
  • Excellent composite laminating resin ideal for hand layup and vacuum bagging.
  • Great for high-color applications requiring a clear, non-yellowing resin system.
  • UV-stable formula with relatively low viscosity.
  • First USDA BioPreferred Certified liquid epoxy resin system.
  • CLS requires corresponding size of Entropy CLR Epoxy Resin or BRT Epoxy Resin for use (2:1 mix ratio). See chart below.

Entropy Clear Slow Hardener (CLS)/Clear Laminating Epoxy Resin (CLR) System Best Uses

  • Surfboards, SUPs (stand up paddleboards), handplanes
  • Adhesives and sealants
  • Fiberglass boat repair
  • Clear coating applications
  • Natural fiber composites
  • Carbon fiber composites
  • Fiberglass composites

Entropy Optically Brightened Laminating Epoxy Resin (BRT)/Clear Slow Hardener System Best Uses

  • White surfboards
  • Bright white cosmetic marine laminating applications


NOTE: Exact fill weight of 5 Gallon CLS Hardener is 5.139 gallons.

Specifications & Mechanical Data  Entropy CLR/CLS Admixed  Entropy BRT/CLS Admixed 
Color  Clear  White 
Mix Ratio by Volume  2:1 (resin:hardener)  2:1 (resin:hardener)  
Mix Ratio by Weight  100:47 (resin:hardener)  100:47 (resin:hardener) 
Mixed Viscosity @ 77°F  800 cPs  800 cPs 
Pot Life @ 77°F  43 minutes  43 minutes 
Tack-Free Time @ 77°F  8 hours  8 hours 
Ideal Working Temperature Range  Optimal - 70-85°F; Extended - 60-95°F  Optimal - 70-85°F; Extended - 60-95°F 
Ideal Working Humidity Range  Optimal - 0-40%; Extended - 0-85%  Optimal - 0-40%; Extended - 0-85% 
Recommended Full Cure  7 days @ 77°F; post cure recommended  7 days @ 77°F; post cure recommended 
Tensile Strength  9,800 psi  9,800 psi 
Elongation  6%  6% 
Flexural Strength  14,580 psi  14,580 psi 
Compression Strength  12,520 psi  12,520 psi 
Tg Ultimate  171°F  171°F 
Hardness, Shore D  70-80  70-80 
Entropy CLR or BRT Laminating Epoxy Resin Quantity  Clear Slow Hardener (CLS) Quantity  Mixed Quantity 
32 oz.  16 oz. hardener  48 oz. 
1/2 gallon resin  1 qt. hardener  3 qt. 
1 gallon resin  1/2 gallon hardener  1.5 gallons 
2 gallons resin  1 gallon hardener  3 gallons 
5 gallons resin  2.5 gallons hardener  7.5 gallons 
Safety and Handling Information

Despite the natural derivation of Entropy resin products, exposure to these materials represents hazards typical of all epoxy resins. Exposure should be minimized and avoided through the use of proper personal protective clothing & equipment, and appropriate manufacturing controls. All persons who use, store, or transport these materials should understand proper handling precautions and recommendations, as stated in the SDS (safety data sheets).

BRAND: Entropy Resins
Material: Epoxy
Rate Of Cure: Slow
Type: Hardener
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