molding - WIP

Mike Chapman

Hi all, 
I am not sure if molding should be a second discussion in this; if not I can post it to the existing thread.

Here are the molds I ran for the prosthetics. They came out OK, although I have some problem areas that I hope do not affect the castings. I should have spent a few extra dollars on larger acrylic sheets as I don't think I have the ideal amount of lip on my outer mold to draw the scraper across the top. also, when I added the keys, I expected the silicone to settle to a glasslike surface (as the other layers did). It left some raised areas- although it seems to key in OK, it may not seat 100% in all areas.

Mike Chapman

I had a few other issues, the silicone seemed to exhibit some saucerization around the edges - I am not entirely sure what caused it (Mold star 30 for the outer mold) - also, the thin edges were to thin and split along the seam between the two molds in areas, so it doesn't sit flush. Since this is in the overspill area, I am not too concerned if I lose it when I run the prosthetics. 

Neill Gorton

These look fine. You can trim back that raggedy overspill area. Most of it came off on mine anyway. I just overlap slightly when making the mould to make more of a seal when pouring up the block of mother mould. Stops anything seeping down between the cutting edge and negative detail mould but it's served its' purpose once the mould is finished and can go without effecting the end result.

Sue Lee

Hey Mike,  
Regarding the clear silicone that had the saucerization, did you double cup when mixing? (pour the mixed silicone into another cup) If you just poured A into B, and scraped every gram out of the cup...then you might have just scraped some unmixed B.  It happened to me and now I double cup when using clear silicone.  I always try to pigment one component if I can to ensure proper mixing.