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I know you are supposed to wash resin and 3d printed stuff, but are you also supposed to wash GW plastic sprues before assembly?

If you're base coating with a spray, it's not generally necessary, no. There can sometimes be small amounts of mould release remaining on the plastic, but the solvent in the spray will take care of it.

If you're base coating by just brushing on regular acrylic paint, then washing the sprue in warm soapy water before assembly is not a bad idea, as the traces of mould release can sometimes cause issues for the acrylic paint.

Resin (cast) and metal models need washing in warm very lightly soapy water and with some agitation from a worn toothbrush to remove mould release from the surface.

3D printed resin needs IPA washing to get the wet resin off the surface prior to curing (remembering to let the model FULLY dry before curing as IPA wetness on a model can induce warping and prolonged curing times).


Plastic models I've honestly never washed; but Insaniak raises a good point since I've never used brush-on primer.

Generally speaking, release agents are not automatically necessary for plastic injection molding, whether you need it or not depends on a number of factors like geometry, surface texturing, materials used, etc. When it is used, the properties of the agents used limit the amount of resudue left on the castings or the pressure and temperature in a plastic ejection mold causes the release agent to burn off, etc. so theres no real residue

I don't think you're supposed to wash the sprues per se. But if you are an uber-OCD modeller, of course you will wash and sand all your plastic parts to absolute perfection before assembling, let alone priming..

You'd be suprised just how much extra sanding is required for some of the flat panels of model kits. GW injection molding isnt super tight, something like the wings of a Valkyrie contain clearly visible "lines" across the wings, which any OCD modeller has to deal with before priming.. So might as well wash em or at least rinse and dry them after, in order to get rid of all that sanding residue.

At the end of the day, its up to you to decide what standard of modelling is appropriate for your hard earned moneys worth..

Just skimming over the previous posts, I agree, but something I didn’t see mentioned & this especially goes for larger models ( and ESPECIALLY for spray paint & airbrushing) wash the model or large parts before painting. The oils in your skin can play havoc on a smooth paint job.

 insaniak wrote:
If you're base coating with a spray, it's not generally necessary, no. There can sometimes be small amounts of mould release remaining on the plastic, but the solvent in the spray will take care of it.

If you're base coating by just brushing on regular acrylic paint, then washing the sprue in warm soapy water before assembly is not a bad idea, as the traces of mould release can sometimes cause issues for the acrylic paint.

I've been in this hobby for 22 years without a break when I learned this now.

But of course. Moulds require release agents. I cast Carolean tin soldiers before I got into Warhammer.

This explains a deal for someone who often just basecoat miniatures with a brush.