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A little colorant turns clear resin into something, but a little too much and the resin never cures. The amount is a share of the mixed batch by weight, and the safe share is smaller than most people expect. This gives you the colorant to add for your batch and your colorant, and warns you before you cross the line where the cure fails.
Measured against the whole batch
Colorant is dosed as a percent of the total mixed resin, parts A and B together, by weight. So the first step is to weigh your batch, then take the right share of that. A couple of grams of mica in a 200 gram pour is a one percent load; a few grams of liquid pigment goes a long way. Because it is by weight, a scale beats eyeballing, especially for small batches where a splash too much is a big percentage.
Less than you think gives full color
Pigments and mica are strong, so full, saturated color usually comes at just a few percent. Translucent dyes and inks color even lower, and they stay see-through only while the load is light; add too much and a clear tint turns muddy and opaque. Start low, stir it in completely, and judge the color in a thin layer against white, because resin always looks darker in the cup than it will in a thin pour.
The hard limit is the cure
The reason to be careful is not just color, it is chemistry. Colorant is not resin, and above roughly ten percent by weight it dilutes the mix enough that it will not cure properly, leaving the surface soft, bendy or forever tacky, with no way to fix it after. Different colorants have different limits, and some makers stay well under six percent to be safe. When in doubt, use less and add a second tinted layer rather than overloading one.
Test in a cup first
Color is hard to judge until it cures, so for anything that matters, mix a small test batch at your intended load, pour a little, and let it set before committing the whole pour. That tells you both the final color and whether the cure is healthy at that load. Keep notes of the grams per batch that gave a color you liked, and you can repeat it exactly next time instead of guessing again.
More MakerKiln tools
- mix ratioEpoxy Mix Ratio CalculatorResin and hardener amounts for a batch, by volume or weight.→
- epoxy coverageEpoxy Coverage CalculatorResin for a flood coat or deep pour, from the area and depth.→
- resin volumeResin Mold CalculatorThe resin a mold needs, from its size, so you mix the right amount.→
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