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I'm going to make an Alien Pod as an art project. Normally I would create the basic shape using foam, wood or clay, and then pour the resin over the top and harden it with a UV lamp, leaving the scaffold/structure in place inside a resin shell.

This time I'm looking to make a model that is translucent, so I need to be able to remove the structure that it's built around afterwards.

Most of this can be done easily simply by leaving a hole in the underside and breaking the scaffold up with a knife and pulling it out. But I need to make sure that whatever is actually touching the resin will peel off of it without leaving bits behind. Which rules out things like paper or foil.

Is there something that I can wrap around the scaffold that will not stick, or which can be easily pulled off, preferably something that can be painted on or which comes in sheet form?

Molding silicone is out, as it drips off before setting, so I just end up with a puddle at the base.

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    It's not unusual for makers to apply spray-on mold release to a surface to ensure that the resin releases cleanly from the mold. Have you considered such a substance?
    – fred_dot_u
    Jan 2 at 17:09

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As fred_dot_u mentions in a comment, you can use mold release (although if you make the structure out of something porous or absorbent, you may need a lot). In terms of a non-stick wrap or coating, a couple of readily-available materials work well.

  • If the project lends itself to wrapping with something in sheet form, use oven parchment paper. That is impregnated with silicone and is a great non-stick surface.
  • Another wrapping that not much sticks to is HDPE, which is a common material for plastic bags (it will be printed on the bag or identified on the retail container). You might want to test a spot to confirm that your resin peels off easily. Cut the seams off the bag to create sheets.
  • If you want something to apply to the surface, silicone caulk (100% silicone, not siliconized caulk), is good. You can smear a thin layer with your finger, or thin the caulk to paint consistency and paint it on. You can thin it with a number of solvents, like paint thinner or xylene, but limonene works even better (pure limonene, not a cleaner that contains it). If you go the thin and paint route, give it at least several days for the solvent to evaporate out (until you can no longer smell it).
  • Another material that not much sticks to is wax. Melt a low temperature wax and brush it on. If any wax bits stick to the finished resin, they are easily removed. If the item will fit in a freezer, that will make the wax brittle and easy to wipe off. Otherwise, blow a heat gun into the cavity (low enough temperature setting so as not to scorch the resin), melt the wax, and wipe it out with something absorbent. Vaseline is often used for this purpose, but it can be hard to clean off for an application like this.

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