[Katherine Swift]

This question comes from Adam:

I have been unable to answer all of my questions in the forum. I am creating a sculpture that will take about 2 gallons of resin to fill the mold and has plastic items embedded inside. The mold is a flexible silicone rubber. I have been casting it with a resin that requires ventilation and warm temperatures with great success, but it is difficult to cast in the winter time since I do it outside for maximum ventilation. That product does not require a mold release.
Your product was suggested to me as one that needs no ventilation. I am planning on buying a small bottle to test before I commit to the gallons I need for the large sculpture. Questions:
1) How thick can I cast in a single pour?
2) Is there a restriction on thickness if I cast in layers? I read on your site that I should mix no more than 4 oz at a time (I can’t remember specifically which of your products)….is there a way around that since I am casting a large sculpture?
3) Do I need a mold release for a silicone rubber mold?
4) The video on your site said that the cast product could survive 55 degrees (I assume celsius?)…I plan on having some of these sculptures outside in full sun during summer time. What will happen to the product if it gets up to 55C?

[Katherine Swift]

Hi Adam,

Thanks for taking the time to email us. I’m not sure which product you are referring to, but I will do my best to answer your questions.

1. I don’t worry so much about the thickness of a resin pour as how much resin you can mix at one time. Depending on which resin you use, you need to make sure you follow the minimum and maximum mixing amounts.

2. No, there isn’t a restriction in the thickness of the layers as long as you are following the mixing amount rules. Know that by pouring the next layer when the first layer has started to gel will minimize the the lines between layers, but that heat is additive. i.e. it may cause your next layer of resin to heat up quickly and cure much faster than expected. (This isn’t always a good thing.)

For the resins we sell, there is a PDF link in this article that talks about mixing amounts: https://www.resinobsession.com/resin-frequently-asked-questions/resin-casting

3. If all goes well, a mold release is unnecessary, however, I always use one because it prolongs the life of your mold. It can also make it easier to demold your resin casting.

4. I don’t recall a video that mentions a casting surviving 55 degrees. If you can provide me with a link, I’m happy to look into it. I will say though, that while a resin casting can likely survive outside in those temperatures, the UV light will cause it to yellow.

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