Great post and I share many of the same experiences. I am demolding one of my first synth casts of just a basic key this evening. A question I have is about hardening the clay on sclulpted masters. Sculpey you can cure in the oven but I am concerned that the keys I have may melt. How are you hardening the final master so you can preserve them properly? I have cast molds from clay in the past and was able to maintain the clay sculpture for later molds.
Again, thank you!
I have not recovered a clay master to date. I used milliput extra fine for the DSAhh basic sculpt, which cures hard in couple hours, and I'd recommend trying it out as an alternative to super sculpey. All unbaked masters of course get smashed.
With the $ynth, you are left with a clay master with a relatively thin base wall due to the pretty generous tolerances of the $ynth mold, even if you bake it. I am
completely fed up with using the multi-purpose smooth-on mold release for this purpose, and will be purchasing some of Smooth On's silicon-specific mold releases very soon (with GID and fluorescent dyes!). I have had awful recent experiences with the Oomoo silicon sticking to the $ynth and master. Vaseline releases far better, but brush application is visible in the mold. I'll update with info on the silicon specific mold-release as I have it.
To attempt to preserve the original as much as possible, I set aside the
second resin casting. The first resin casting tends to pull tiny remaining slivers of clay from the mold. I'd like to attempt to create a two-part mold of multiple identical caps using a similar method and without relying on the $ynth, but I haven't yielded a sculpt worth doing this for yet. Blanks would be a good candidate.
PBT plastic has a melting point of 433(F)
ABS plastic has a melting point of 221(F)
Super sculpey calls for baking at 275(F)
I am not a chemist. The ABS melting point is approx 50(f) higher than super sculpey baking recommended temperature. You can clearly use a PBT cap with no problems, though. Practically, for making blanks, you will need the blank to stick to the clay and to the $ynth. It may stick better without baking while the clay is tacky. You can google around for "parbaked" super sculpey, but you may be able to fully cure at 220 for a longer time.