White substance on Painted printed objects

[Bruce Archer]

Hi All!
    I do not know if this is the correct forum for this, but here goes.
   I recently bought from Shapeways several D&H prototype cars. The Ilmenite Hoppers bracing on the ends was extremely brittle and was replaced with sheet styrene. All were washed in dish detergent, and primed with Polly Scale Primer Grey. Then they were painted with either Polly Scale, Modelflex or Testors paints. A couple of months later the surfaces began to have areas of a white substance, which has ruined the finish.

1- What is happening?
2-How do I stop it?

This has made me gun shy of buying any other 3D printed items

Bruce Archer

[John]

Bruce -- shapeways products need to be cleaned with bestine https://shop.archsupplies.com/products/bestine-solvent-thinner-for-rubber-cement or similar ..

Others will chime in with alternatives I'm sure

[Lemosteam]

Shapeways uses a wax filler to support the print as it completes. then the melt the excess away during the pots print cleaning process before they ship.  Unfortunately this leaves a clear looking print, but what you are looking at is s thin layer atop a wax-soaked resin printed model.

You must clean (not wash) the print prior to any finish.

@John is correct on the Bestine bath, I use a 20-30 minute sonic cleaner in Bestine as the added natural heat from the fluid in the UC breaks down the was further (IMHO).

Depending on the level of detail, I then use an air eraser to remove any additional print artifacts and smooth the surface.

The material is quite porous after cleaning.  Some have been known to brush on thin CA and let it soak in, or several coats of thinly applied primer.

In several years, I have not seen this phenomenon, so far.

Good luck.

BTW- DO NOT try to strip the material- it will break down. Better to use an air eraser/bestine after, and then repaint?  Not sure i have not had a reason to try and fix this issue.