Thread: Options for colouring polyester resin.

i tried some of the feast watson black spirit dye in casting resin. it didnt seem to mix with the resin at all..it sort of did which made me satisfied enough to pour the resin into the redgum burl voids. some of the voids were pretty big, 55mm deep and about 100mm long and 30mm wide, so it took a few goes to get it filled completely. as I was doing each batch I found that the spirit stain was leeching out of the resin and into the timber a little bit staining the timber. it gave a kind of translucent resin fill, you could clearly see that the stain had completely saturated the walls of the burl voids. I ended up just using black oxide on the final batch which gave a consistant opaque colour.

I wont be using spirit stains in resin again unless I have fully sealed the timber prior...but that probably has some other issues with adhesion which I'm not aware of.

The biggest problem with a lot of additives is they sometimes don't mix with the resins. All I can say is try in a little bit and see what happens.

As far as vacuum, don't use a normal gauge for vacuum, you can stuff it. Your venturi pump will work, but not necessarily get to full vacuum although you shouldn't need it. Be careful of your compressor though, venturi pumps take a lot of air, often too much for a back yard compressor.

As for translucent dyes, yes the more you add the less translucent it is.