Tinting gelcoat possible with this method?

Discussion in 'Fiberglass and Composite Boat Building' started by Wynand N, Jul 18, 2010.

  1. Wynand N
    Joined: Oct 2004
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    Location: South Africa

    Wynand N Retired Steelboatbuilder

    Can gelcoat be tinted with automotive 2K (poly-acrythane) epoxy paint toners instead of gelcoat pigments?

    I need a funny sort of Caterpillar yellow for some big series of mouldings. With automotive toners (tints) it should be possible to perfectly match the clear gelcoat to the required colour.
    But is it possible and what would the colour quality be?
     
  2. waikikin
    Joined: Jan 2006
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    Location: Australia

    waikikin Senior Member

    Wynand, I dont know if the 2K thing will work- sounds a bit dodgy, yellow gelcoats often need a back up of white to "look" the colour, your gunna have to do some tests including shooting the right cat colour in 2K. Regards from Jeff.
     
  3. Herman
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    Herman Senior Member

    Do some tests, but do not be surprised if you cannot disperse them efficiently, or that they might inhibit cure, or yellow due to UV radiation. Sometimes pigments can do funny things.

    Is your supplier not able to delliver you what you need?
     
  4. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    Like Herman said, its best to have the supplier match the color.

    Gel coats are limited in the pigments that can be used because many can mess with the chemistry, some will inhibit the cure and others will speed the cure or shorten the shelf life.

    Current pigments used to make many yellows have poor hide and color retention due to federal regulations that stopped the use of many popular and inexpensive types. This also limited the colors that can be matched, many times we can only get close to the color that was desired.
     
  5. Wynand N
    Joined: Oct 2004
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    Wynand N Retired Steelboatbuilder

    I actually did an experiment. I had my paint supplier mixed me a liter of very fancy and "difficult" colour in 2K and I added that to clear gelcoat to a ratio of 20% of volume of GC.
    It mixed properly, done a test piece with a couple of CSM layer over the mixed gelcoat and it worked like a charm. The result the same as if I used pigmented gelcoat.

    The leftover mix in the bottle still perfect after 5 days and no ill effects on the test piece.
    Now the sky is the limit with gelcoat colours in my workshop.:cool:
     
  6. waikikin
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    waikikin Senior Member

    Wynand, you may well be on to something there but before you supply finished product to customers a longer test time may be very appropriate for UV, bonding etc, I am a Shipwright & not a Chemist so I trust the formulators Of Chemicals such as 2K & Gelcoat to do the Job- mix & apply, both are well proven although so far as I know the yellow gelcoats now need a white back up to look right, both are easy to use, 2K paint is pretty easy to spray.
    All the best in your endeavours from Jeff.
     
  7. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member





    For a manufacturer 5 days isn't enough of a test, we need to ensure the customer that the product will be good for at least three months in almost any type of weather conditions (high heat). At the end of three months all aspects of the gel coat should still be within the original specification window. We also test for water and UV resistance plus gloss retention before approving pigments.

    Short term, as in this case where you only need the product to be stable for a few days or a week the cure issues may not show up and it may work well. It also depends on the color you're trying to match, some colors use a neutral tint base (clear), others use a white tint base, or even a blend of the two. Pigment loading can be a problem, we check and adjust the product into spec after the correct color has achieved, this helps to eliminate the effects of the pigments and their carriers.

    Check the viscosity of the final product, with a 20% add the viscosity may change enough to greatly increase the chance of sagging. Porosity can also be a problem with high pigment loading.
     

  8. simon99
    Joined: Nov 2007
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    Location: dubai

    simon99 Junior Member

    hi ive tryed this around 2 years ago and i work in Dubai and the heat here is hot after 3 weeks of doing the i done the test on a sample all started to crack and come away and the gel started to change colour like it was starting to separate
     
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