Making Molds from Shapeways

[John]

I put this topic in here because the part is 3D printed 

I have some shapeways military vehicles that I want to use as masters for my MT DODX flats.  They have all been in the Bestine bath,  The first attempt at making a mold was a failure. The RTV sticks to the master. I used a mold release on the part, but its hit or miss. The Shapeways parts are porous and prone to sticking and tearing. I've used Amazing Mold Rubber from Alumilite for small parts before with out problem, for example, the original MT Stryker load was a very good pattern to make a mold on - no sticking or tearing. 

Thoughts?  I'm thinking of either vaseline or Mr. Surfacer

[Lemosteam]

Sand the model reasonably (not perfectly), use four coats of Tamiya TS-6 black or Fine white primer to completely cover the print.  It will fill all pores completely. I would not sand again. That is what I would try with mold release again.

[John]

Sand the model reasonably (not perfectly), use four coats of Tamiya TS-6 black or Fine white primer to completely cover the print.  It will fill all pores completely. I would not sand again. That is what I would try with mold release again.

Thanks .. I have some Tamiya white primer in stock . .will try that ..

[Rasputen]

Mr Surfacer works great for me

[Dirk Jan Blikkendaal]

My molds from Shapeways originals are made from MOLD STAR 15 platinum silicone rubbers, using Ease Releae 200. Never a release problem even with untreated (no sanding no coating/primer) surfaces.
To get rid of the "white fuzzy stuff' (remnants of the support material) I highly recommend blasting the original with a Master Air Eraser using alu oxide........ just recently discovered....... greatly improves the Shapeways surfaces without any damage to detail. See my other post. Good luck, Dirk Blikkendaal