The experimentation really never ends when it comes to urethane. With each new project comes new demands on the materials, which means developing new ways to use them.
Regular readers will know that the "holy grail" of urethane for me is a product that can be applied in very thin layers, but will be very opaque and most of all will not pull back from silicone. My existing molds are silicone, and I don't want to have to remake them as rigid molds. Though frankly, that probably would have been a lot faster, and saved me a lot of heart ache.
My favorite product for silicone molds right now is Smooth-On Brush-on 50. Or 40. It's a great product that does most of what I want. Ideally, I would be able to apply this with an airbrush. The problem is that when I thin it with mineral spirits so that it will flow through a spray gun or airbrush, it tends to lose some of its more interesting properties. I've been searching for a better method, and the other day decided it might be worth trying to apply it with a paint roller.
I picked up one of those dinky little touch-up rollers from home depot, and gave it a try.
The results were fantastic. In this picture, you can see how the detail of the mold was not lost. No bubbles either. Pretty much any flaw you see in this pull was a flaw in the mold. Very nice!
Here's what it looks like on the inside. Not as uniform or smooth as one might get from an airbrush, but still workable.
Because this is VERY thin, it is also very flexible. I doubt I would ever brush it on this thin in a production piece, but this is a neat image as it shows just how much abuse this stuff can take.