As you may remember, I’ve been fiddling around with resin casting, working up to sculpting and casting my own wargaming minis. I ran out of the white resin I’d been using previously, and broke out the Smooth-cast 325 I bought a month ago. It’s “clear” and, in theory, tintable, although I haven’t sprung for any of the colors they sell for it. Allegedly, it’s got the same work and demold time as 300, which I’m now quite comfortable with.
I tried to run up some quick-and-dirty armature casts for the torso and arms of a Destroid Phalanx/Longbow LGB-0W that I’m sculpting.
Short story? It did not go well.
I pulled three casts, all with small amounts of resin; I decreased the amount in each cast for reasons that will shortly become obvious. First, of course, I stirred the separate parts thoroughly and jostled out the air bubbles.
Cast 1: mixed up about 3T of resin, enough for ~5 models (why waste the pull, after all?). The resin began reacting almost instantly; it hit “honey” consistency within 30-45 seconds, and was over 100 degrees and unpourable in less than a minute. The resin itself started “frothing”, with hundreds of micro-bubbles in each cast, and gave no visible indication of its cure state, so I had to guess by tilting the molds and watching the flow. I also had to weight the molds to keep the slight swell of the frothing resin under control.
Fast forward 20 minutes, as I check the demold state for the third time. Somehow, it’s got a 30-second work life and a 25-minute demold time. It doesn’t fully cure for over an hour on 28mm minis, apparently.
2+ hours later, even the resin that froze in the cup is still rubbery and overly-flexible.
Cast 2: I figure I mixed too much, since mass speeds up the reaction, and I measured part A more carefully – I’ve had “frothy” results and a slow cure when I overuse Pt. A in the 300-resin (Overuse Pt. B and it gets “greasy” and smooshy). Mixed about 2T, and worked much more quickly than the previous time. Still only managed to pour 3 models before the resin froze, wasting half the material. Again, microbubbles and slow-ass curing the order of the day.
Cast 3: “Fuck it”, I say, and break out the gram scale. I mix the exact 1.00 B : 1.15 A ratio by weight from the Tech Bulletin, very quickly and thoroughly, and poured only three models. The resin was STILL sliding into “unworkable” territory in the middle of the third pour. The cast had a little less foam this time, but it’s far from “clear”, and as we speak the models are still curing in the mold.
We are displeased.
The complete lack of a visual indicator of cure state, obscenely short work-time, and bubble-fest in the resin itself combine to make me a singularly annoyed little monkey. Gonna buy some 300-series on the 1st and do throwaway terrain work with this shit.