Colouring epoxy resin

[Michael Rogers]

Does anyone have clever practical tips about getting the colour of epoxy resin to match the wood being glued? Appearance-wise this can be an issue in areas to be varnished, danish-oiled or whatever rather than painted. I'm possibly out of touch, not having used large amounts for some time: do any of the epoxy systems people offer fillers for use in matching hardwoods? I don't think West do. One of their fillers dries a darkish pink, which isn't much help on its own. I have saved an amount of very fine sawdust from mahogany which I have mixed in - not too bad, and only a small amount needed to darken the resin, but it does need to be fine (put it through a coffee grinder?) to avoid a granular appearance. I've tried fine dried coffee grounds, but it doesn't work very well. I find 'bright-light-brown' woods difficult. The whole thing is made more complicated because the colour after full cure is often different from that of the runny stuff.

Bright ideas, anyone?

[Guy Rossey]

Does anyone have clever practical tips about getting the colour of epoxy resin to match the wood being glued? (...) I have saved an amount of very fine sawdust from mahogany

[Michael,
one might add some liquid ink - as used for graphic design and available in different hues- to epoxy resin so to match the right colour of the wood. They are intense in pigments and transparent, not much would be needed and hence they should mix well enough with epoxy resin.]

[Michael Rogers]

It's an idea, Guy. Would it be a good idea to check with West Systems that it's OK to add inks to their resin? Might it depend on the chemistry of the ink vis a vis the resin? Explosions used to be fun in chemistry at school (though not often achieved), but I seem to have lost my enthusiasm for such possibilities. Still, you never know.

The obvious answer is for me to contact WS, since I asked the question! I'll do so. I'm just a bit surprised that this practical issue hasn't already been addressed and solved by 'someone out there'.

[Guy Rossey]

Yes, Michael, it would be interesting to know what West recommends here.

Out of curiosity I checked what's known in the field on the web and found these articles:

1.   effect of fillers on epoxy :

"(...) In a variety of applications of aqueous epoxy resin coatings, the dimensional stability and consistency can be significantly increased by adding special pigments and fillers. An increase in the percentage of fillers induces a decreasing portion of resin used and thus also the moiety responsible for the shrinkage in the formulation. Usual dosages of fillers can be as large as 70 percent. A well-balanced adjustment of the binder with the fillers is however a prerequisite to achieve a stress-free coating with low-grade shrinkage. By controlled drying and curing conditions, coating shrinkage can be further minimized; these are nevertheless, particularly in construction, often not controllable.(...)"


      in : http://www.pcimag.com/Articles/Feature_Article/090792a77e6a7010VgnVCM100000f932a8c0____



2.   here a test of another way of doing where they ( West Systems ! ) apply epoxy OVER  stains of different nature:

      http://www.westsystem.com/ss/epoxy-adhesion-over-stains

There are solutions available but some trials not to be done on something else than the boat before ( in case it explodes... ).

Good luck!