decorative surfaces

Gelatin Molds For Plaster Casts

A couple months ago I was sent a question about using gelatin molds for casting architectural plaster.  I had seen references to the technology in several of my old books but did not possess any that provided a decent description of the material or the process, so I noodled it a bit.  I’m not an architectural historian per se, so there might be plenty of old books with the exact information.

For the past almost forty years I have relied on silicone RTV molding rubber and never saw the need to broaden that horizon, but this question prompted me to undertake some exploring.  I am awfully glad I did as I now have another potent arrow in the quiver.

Of course at issue were several considerations.

  1.  The gelatin (hide glue) would need to be used in the semi-cured state, in other words after it had gelled and had not yet lost enough water to enter the more solid phase of a dried, cured mass.
  2. The gelatin mold had to be firm/flexible enough to actually cast plaster into it, then have the casting de-molded ex poste.
  3. The mold needed to be robust enough for repeated using.  The literature references using the molds dozens or even hundreds of times.
  4. Finally, the mold needed to remain viable while not becoming a giant fur-ball of mold.

Thanks to a timely failure of a tordonshell batch I gleaned the path to success, when combining that experience with some noumena from my wanderings into materials science.  The ultimate result was a high performance molding material that was also cheap.

The trek included a number of face palm moments in discovering new ways of working.

Stay tuned.