Resin casting mold release

I've always used silicone spray. (If you use silicone first, then talc, it will give your castings a nice matte finish.)

I think the last time, I found the spray on sale at Staples, of all places.

I don't cast with resin, but with white metal.  I use talcum powder as a release agent with my silicon rubber molds.  I'm surprised that you couldn't find any in local drug stores, but I suppose it reflects ongoing logistical disruptions caused by the lockdowns.  Did you try grocery stores, too?  They might have had it in their health & beauty aisles.

With metal molds, I use soot to lubricate them.  I hold the mold halves over a candle flame and let it deposit soot in the cavity.  Of course, you can't do that with rubber molds

Most all talc powders have been pulled because if the lawsuit on cancer in women.  Try looking for medicated powder, such as Gold Bond or Equate.  Wonder if foot powder would work?

If your preferred release is unavailable, an old trick is to use nonstick cooking spray. The oils in those aerosol cans is inert and food-safe, so it won't attack the mold or interact with the resin as it sets up. Works well with both latex and silicone rubbers, plus it cleans up with dish soap and water.

Caveats - some brands tend to foam up, so test things before you commit to mixing your resin for the pour.  Extra gas being trapped in the mold can be a nightmare. 

Resin castings done this way will sometimes have a bit of a greasy feel to them because of the oil, but a light wash takes care of things quickly.

the Baron

I don't cast with resin, but with white metal.  I use talcum powder as a release agent with my silicon rubber molds.  I'm surprised that you couldn't find any in local drug stores, but I suppose it reflects ongoing logistical disruptions caused by the lockdowns.  Did you try grocery stores, too?  They might have had it in their health & beauty aisles.

 

No, the issue is cancer scare.  Turns out talc has asbestos fibers in it.  It is no longer used for babies.  I did find on line a brand of after-shave product that is still talcum, but I will have to wait a week or so to get it, and wanted to get casting finished before then.  Used wax instead.  Forgot about silicon spray.  I'll use that before the actual resin pour.

When I was making bitts and chocks out of two-part epoxy, I used soldering flux as the release agent. It seemed to work fine. You just have to clean the part afterwards, but I'd think you would have to do that anyway with whatever you use.