Thread: Resinating a WIP

I have regretfully concluded that, after several attempts, turning my apartment kitchen into a woodshop was not going to be practical. Routers and power sanders don't seem to be a good fit with pots and pans. And I live alone, so my mess is my own.

Following earlier threads, I have gotten into doing some urethane resin casting of celluliod scales with fancy designs. I like the old designs and would like to keep the patterns after the celluloid is long gone. With the modern resins, we should be able to create scales for your blade's next 100 years.

I need some advice from those who have done it before. It's as much about finishing as quality control.

I’ve been making molds using RTV platinum silicone and have had middling luck. There are two primary issues, one is crowning above the part line with the urethane and the other is degassing. I can get the mold flat and level but after the pour there often seems to be a crown in the finished product. In order to get an even line on the edges of the scale, the whole back would have to be sanded. Which would mean a belt sander, something I would hope to avoid.

Here are some WB replica's in chocolate brown that have that problem.


The other issue is bubbles. In opaque casts, interior bubbles aren’t a problem until they form along the part line. This is today’s work. It has a green translucent base and brown iridescence.



It has minor bubbles that can be seen if held to the light.



The issue here is that, like pitting along the bevel when you're honing, they tend to form at the part line and if I sand them completely out, I’ll destroy the pattern, or at least the two sides probably won’t be symmetrical.




Vacuum degassing will probably solve bubble issue (do you pressure cure?) but the crowning has me scratching my head. A small pump and chamber set up is easier to live with that the dust. Any help?