I note you state add pigment to part A of Water Clear Polyurethane Casting Resin. What is the downside of adding it to part B in error please?

The polyurethane pigment dispersions contain a small amount of "part A" of the polyurethane resin ie the polypropylenglycol part.

Adding it to part B to mix and then soon after adding Part A would unlikely cause any problems.

However, if you wanted to mix it in advance, you would find the isocyanates in Part B would react with the small amount of part A resin in the pigment.  This may have an effect on any casting you do although with the proportions being small, it is hard to say how much of a problem this would cause.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

Warren

I actually mixed approximately 2cc to 100 grams of B but there has not been any apparent curing. Many thanks.

Regards

Hi Ray,

As Warren said, the amount of resin base in the pigments is very small which explains why you've not encountered any curing problems. If it seems to be OK on this occasion then I don't think there's too much to worry about. In future, switching to Part A when pigmenting in advance will give you peace-of-mind.

Kind regards, Matt

Matt Statham
Easy Composites / Carbon Mods - Technical Sales