Mold Experiments, days 5 and 6

Well, new year, and first case of food poisoning on day one. Well played, /13..

In molding news:
The Scriptarius method (caulk accelerated by acrylic paint) produces a tough, heat-resistant, and detailed mold.. but it’s not reliable. Or especially good at preventing surface damage and imperfections. It also stinks like a mother.
Worse, it causes lead rot: acetic acid is the curing agent and causes lead corrosion. So old models (the kind you most need to cast bits from for, say, repair and mirroring) will be destroyed.
It’s cheap as hell – ~$8 for materials made enough for about 8 mold halves – but I had to throw away every single one of them. Only two halves of two separate molds came out acceptably, even after I ruined an old paintbrush brushing a thin layer onto the master before pouring the structure. The quality of any individual mold half and pour also varied wildly, even though my last four pours were made with identical quantities of identical paint, the same amount of caulk, and nearly identical mix, pour, and cure times – halves ranged from dense, detailed, and opaque to translucent and spotty with almost no rhyme or reason.
I may try again with a thinner master, or try to find a less-viscous form of base RTV, but for now.. the tin-cure won.

My first tin-cure throw took about an hour of carefully prepping the matrix and mold box, and then another half-hour or so of cleaning and checking the first mold half for issues. I used leftover rubber from the first batch as filler on the second and subsequent batches of rubber. The first cast off of it, however, was perfect. Lots of flash, not like I wasn’t expecting that.. but no surface flaws, the mold lines matched perfectly (the hardest part of the prep work), and the cast model actually has sharper detail than the master, which I blame on the superior casting material.
The tin-cure is expensive – $25+ a kilo – which I currently estimate will last me for another 12 mold halves discounting filler. On the other hand, it’s thin enough to work well, even if it is more toxic.

Speaking of which; I’ve been working a bit with Smooth-0n 300 now. It’s amazing how far it goes – 1T made a bulky 28mm model with flash to spare. It’s fragile: bendy and rubberlike as you first pull it from the mold, but subsequently becomes more brittle. If you want to adjust a pose or the like, do it fast. It also helps to run a little wire inside the mold before you cast, especially inside thighs, upper arms, and other fragile bits (although you can also use plastic rod/strip; I used Q-tip shafts [the hollow rubbery soft plastic kind] in my second mold with no adverse effects) to strengthen the parts.
My first cast seems to be holding the primer (standard Krylon flat black spray) well, and I’ll paint her up tomorrow. I’ll mix it in with some of my other stuff in the pics, I think..

Also, more tutorially stuff, hopefully with more pics, to give you a better step-by-step feel for the process.

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