Coloring Epoxy to Fill Knots

Advice on tinting epoxy to match slab table tops. December 24, 2009

Question
I have been making a few slab tabletops that have some knots or decay that I need to fill. I have been using glue mixed with sawdust, but I would like to use epoxy that can be colored. What medium works best for coloring?

Forum Responses
(Adhesive Forum)
From contributor A:
I have been using epoxy for this purpose for years now. We mainly use black but on occasion need custom colors. We use System 3 and they make quite a few different pigments for this. You can order from their website. It is also carried in small jars by Woodcraft. A little goes a long way so unless you are doing large volume, check Woodcraft - either the store or the website, though I am sure there are others. If you try any of the hobby or home remedies, do it on scrap first.

I was in dire need of black to finish a large void one time. No pigment was available and some guys talked me into using something "they used one time". The problem was that every time the epoxy got hot, it boiled, leaving millions of bubbles that I never had before. This taught me to check it first, no matter how good someone says it works.

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From contributor B:
Marine supply stores carry a range of colors of liquid pigments that can be added to epoxy as well as polyester resin. Jamestown Marine Supply is an excellent source. Defender Industries are excellent as well.

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From contributor A:
As I said, be sure and make a batch with your epoxy and see how it cures. I have had some that cause the epoxy to harden more or less, but will still be soft enough that I can dent it with a finger nail. The System 3 pigments are actually colored epoxy resin and not a 3rd chemical in a 2 chemical reaction.

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From contributor C: Just add the sawdust you are obtaining from sanding your tables and mix it with any good grade epoxy. The color will be closer than what you will achieve with colorants without a lot of test batches first. The problem with colorants is you may think the color is close, then you sand smooth and the color changes and you find yourself unhappy with the final color. By using the dust from the wood you are applying it to, you will be much closer.