Butanox M50 MEKP Polyester Hardener

  • Butanox M50 MEKP Polyester Hardener
  • Butanox M50 MEKP Polyester Hardener
  • Butanox M50 MEKP Polyester Hardener

1-2 days

    ✔ Hardener for all polyesters
    ✔ Methyl ethyl ketone peroxide (MEKP)
    ✔ Very stable and reliable
    ✔ Clear / Colorless
    ✔ Low water content

    € 2,50 € 2,07 Excl. tax

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    Product description

    Butanox M50 MEKP Polyester Hardener

    Butanox M50 MEKP Polyester Hardener

    Butanox M-50 is the workhorse in GRP curing systems. A general purpose reactive methyl ethyl ketone peroxide (MEKP) with guaranteed low water content, used to cure unsaturated polyester resins in the presence of an in-room cobalt accelerator and elevated temperatures.

    This makes it harder to use. The low water content makes this hardener very suitable for marine applications.

    Technical data

    Density at 20°C: 1.180 g/cm3
    Colour: Clear / colourless 
    Viscosity at 20°C: 24 mPa
    Total active oxygen content: 8.8-9.0% 


    Polyester cures by a peroxide such as Butanox M50 as a hardener. At lower ambient temperatures, more must be used more than at higher ambient temperatures.

    Below the amount of MEKP / catalyst for 100 grams of mixture. This depends very much on the amount of polyester to be produced at a time. Larger amounts generate a lot of heat by themselves and can therefore be mixed with less harder.

    Normal mixing ratio MEKP for 100 gram mixture, at room temperature in °C.

    12-18°C: 2.5% (2.5 ml.)
    18-23°C: 2% (2.5 ml.)
    23-30°C: 1.5% (1.5 ml.)
    >30°: 1% (1 ml.)  

    Please consult the specifications of the resin itself for any deviations. We recommend not to process the polyester resin below 12°C and preferably not above 35°C and preferably between 18 and 22°C. Note: make sure that the polyester itself is stored between 18 and 22°C before obtaining of the best results. Always test which amount works harder in your project.

    If the temperature is too low, curing takes a long time and sometimes it may not even be completely finished. If the temperature is too high (also by using too much harder), there is a great chance of shrinkage and stresses in the cured resin.

    Curing of polyester resins works well at room temperature. It is true that the post-baking of the resin at higher temperatures, as indicated by the manufacturer, often gives a stronger end result. However, in many cases this is not or very difficult to do.

    Use a pipette for small amounts of B component / catalyst. 1 ml is then equal to 1 gram.

    Shelf life

    Store below 25°C. With proper storage (dark and cool but never too cold) can be kept for at least 6 months.


    Keep containers tightly closed. Store and handle Butanox M-50 in a dry, well-ventilated place away from heat sources or inflammation and direct sunlight. Never weigh in the storage area. Avoid contact with reducing agents (eg Amines), acids, bases and compounds with heavy metals (eg accelerators, dryers and metal soaps). Consult material safety.
    Use safety gloves, splash goggles and work in a ventilated area or with a respirator for organic vapors. Wash hands and skin thoroughly after contact or after normal use, rinse eyes and mouth in case of accidents.

    EN - Product Information Butanox M50 MEKP Polyester Hardener.pdf

    EN - Safety data sheet Polyester harder Butanox M 50 MEKP


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