I was wondering what the best way was to preserve a mold. Basically I’m getting a mold for a latex mask and I was wanting to make a master cast of it to preserve it and make a mold off it. At the same time I still wanted to be able to cast latex masks so i don’t really want to seal it unless it’s only temporary (I’m not sure how that works). I know I can make a latex master but then it shrinks and isn’t accurate to the 1st gen mold. So I was wondering if there’s any material that I can cast that has minimal shrinkage and I don’t need to seal. (Again if the sealing is temporary I don’t have a problem with it, I just don’t want to ruin the mold. From what I’ve read to do a resin cast it would need to be sealed).

Hello fellow makers,

I wanted to cheap out on my current project and bought neutral cure construction silicone for my (2 part) mold, which is a 1:1 bust.
Did not have time to apply both parts in quick succession and now that the first part has fully cured, I see that the silicone edge wall has retracted 3-4 mm from the shim wall, which is a mental amount of shrinkage.

This first part is also only about 2mm thick, pure construction silicone. I thought of strengthening it by applying a silicone+corn starch mixture on top of that but again; did not have time until now that the first thin layer is fully cured.

I wonder if I should take the loss, scrap the first part mold and buy proper silicone;
or if applying the 2nd part mold a few centimeters on top of the first part, overlapping the two parts, may give a good result even considering the the second part of the mold will of course shrink just as much.

Thank you for your time and advice.