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Product Details

MAS Slow hardener is formulated for use with MAS epoxy resins and can be applied in a wide range of conditions where increased working time is required.

We highly recommend MAS Slow Hardener when coating or laminating large surfaces. The Slow formulation cures blush free and eliminates the need for time consuming wash downs during on-going laminations or repetitive build coats.

Use this hardener (200-250 poise) with MAS low viscosity epoxy resin for fast wet-out of reinforcing fabrics.

Note: Due to this item's high hazardous content, the 4 gallon and larger containers cannot be shipped by UPS or FedEx under any circumstances.

Available in Pint, Quart, Half Gallon, Gallon, 4 Gallon, and 5 Gallon sizes.

Info & Guides
    Technical Specifications
  • Mixed Viscosity w/MAS Epoxy Resin at 77 deg F: 500-600 cps
  • Mixing Ratio 2:1 Resin to Hardner
  • Pot Life at 77 deg F: 23 minutes
  • Thin Film Set Time at 77 deg F: 5 hours
  • Full Cure: 7 days
  • Flash Point (closed cup): 234 degrees F
  • Specific Gravity at 77 degrees F: 0.998
  • Viscosity at 77 degrees F: 200
    • Performance
  • Flexural Strength: 14,600 psi
  • Flexural Modulus: 535,000 psi
  • Tensile Strength: 8,000 psi
  • Tensile Modulus: 384,000 psi
  • Elongation: 9 percent
  • Compressive Strength: 14,000 psi
  • Compressive Modulus: 384,000 psi
  • Use protective gloves when working with epoxy resin systems. Use soap and water or white vinegar to clean your hands. Use Denatured Alcohol to clean your tools.

    Reviews for MAS Epoxies Slow Hardener

    10 of 10 Reviews

    April 14, 2020

    Great stuff, consistent performance and easy to work with.
    By UCanoe_2 from Shenandoah Valley, VA

    Verified Purchase

    I thought my boat project would take place in winter, so initially ordered fast hardener. Instead, the project has stretched into warmer weather and I need the slow hardener. Like all MAS products, the slow hardener is easy to work with and performs consistently. I just wish they would bring back the Miss MAS T-shirts with the really hot looking mermaid!

    Bottom Line Yes, I would recommend to a friend

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    August 3, 2019

    I am very happy with the MAS line of Epoxies
    By Mark from Cohasset, MA

    Verified Purchase

    I am not an epoxy expert by any means, and Ifound MAS epoxy to be very easy to work with. Additionally, I have found Jamestown Distributors to be even easier to work with, and are now my first choice.

    Bottom Line Yes, I would recommend to a friend

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    May 30, 2019

    Good in the heat
    By MacDuff from VA

    Verified Purchase

    Using to lay out a large section of Dynel in 80 +degree heat and it keeps the epoxy workable just long enough to squeegee out after rolling.

    Bottom Line Yes, I would recommend to a friend

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    May 28, 2014

    MAS epoxy hardener
    By Kretchman fly rods from Kittery Point, Maine

    Verified Purchase

    Great stuff and easy to use.

    Bottom Line Yes, I would recommend to a friend

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    April 27, 2010

    Great product
    By Rich from Stratford, CT

    Not as toxic as other hardeners. 2:1 mix with Mas resin as opposed to 5:1 West Systems. No yellow tint as with West System

    Bottom Line Yes, I would recommend to a friend

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    January 26, 2010

    nice and slow
    By Paul from Maryland

    it works nice and slow giving you a lot of working time. In colder temps it might be better to use a faster hardener but I have not tried it.

    Bottom Line Yes, I would recommend to a friend

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    April 2, 2009

    Great product, easy to work with.
    By DocChicago from Alhambra, CA

    I first used this product while building Skerry from Chesapeake Light Craft. It's supplied with the kit. It's long working time make it very easy to use for the novice boat builder. The beautiful amber hue it imparts to wood and it's diamond hard finish will give you a boat that will be passed down for generations. Make sure to cover with a Good UV varnish so the epoxy doesn't yellow with age.

    Almost finished, waiting to epoxy down the seats.
    Graphite and silica bottom
    Bottom Line Yes, I would recommend to a friend

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    March 7, 2009

    This product has made my work easier
    By Jim wood worker from Greensboro, NC

    I work with reclaimed wood this combined with the low viscosity resin does a great job of filling cracks and securing knots, saves me a lot of time.

    Bottom Line Yes, I would recommend to a friend

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    August 7, 2008

    Excellent working time
    By Buzz from Madison, WI

    The Mas slow hardner system is an excellent choice for people who need a little extra set up time as it is slower to go off than some other epoxies I have used. It sets up clear on it's own and mixes well with additives. I will be using this product on all my new projects.

    Bottom Line Yes, I would recommend to a friend

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    June 26, 2008

    a perfect blend
    By DeLee from Hammond, IN.

    I used the MAS Epoxy resin products for repairs on an Hydra Sports Aero Cobra I am restoring. The slow hardener was a great choice for the repairs I had and did everything MAS said it would. Its slower set up time gave me plenty of time to work. It was easy to mix and apply. I ran out with one small job to do so I bought another brand locally. I greatly preferred the MAS over the other brand.

    Bottom Line Yes, I would recommend to a friend

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