I tried something a little different this afternoon. When I was at MakerFaire NYC last year, one of the Smooth-On reps was kind enough to give me a sample kit of something called UreCoat. It’s a flexible urethane that is intended to skin foam products. Rather than make the foam and then apply the UreCoat, I thought I’d try doing the reverse – brush the UreCoat into the face of the shoulder pad, then backfill with foam. The hope with this process was to leave me with a nice, uniform front surface on the part and preserve the details, like the screw heads, by brushing product directly into them.
While we were at it, we figured we’d experiment a bit with trying to tint the UreCoat and the foam layer that followed, just to see what our options were. I felt like if I could make the base color of the pad an olive green, any flaws or damage to the ultimate paintjob would end up being mostly hidden, or at least blend in. I have a sampler kit of So-Strong tints in a variety of colors that we cracked into. This stuff goes a loooong way – just a few drops is enough to solidly tint most clear materials.
We mixed a bunch of different colors up to try and get something approximately right, then did a pseudo-slush-cast where we brushed it into the surface of the mold and swung it around a bit. The pot life on UreCoat is 8-10 minutes, which is a bit longer than you’d want for this kind of thing, but still short enough that it’s doable.
Ended up doing two thin coats of the stuff, just to be sure. Let it sit for about 90 minutes, then mixed another batch of FlexFoam-It 17 and some green pigment and poured it in behind the UreCoat. A note about the FlexFoam – it was possible to pigment it with the SoStrong pigments (we put a decent bit of green in) but it whitens up as it cures, so any color you try to mix in will basically just be a pale imitation of what it should be. It shouldn’t matter anyway, since I plan on painting the pads, but means I probably wouldn’t try tinting it in future.
Only thing left was to demold the parts and see how it came out!