The addition of a wide range of materials that can improve the properties of epoxy

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Not sure what I would do with them but I did not know you could buy empty caulking tubes …

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This was quite educational also: https://youtu.be/8MOTMq9g8Nk

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Mixing stuff together to get different properties, huh? About as much as I did for that was mix cooking flour in with silicone caulk to make it more rigid. I suppose I could have used about any powder. It was important for the caulk to no longer be flexible and I pretty much succeeded.

Hadn’t tried flour and caulk.

I routinely use 100% silicone caulk and cornstarch to make silicon stuff from molds.

Does corn starch and flour set rigid as well? I imagine so.

The corn starch accelerates the drying time and the result is a stiffer less sticky rubbery silicon that dries in about 15-30min to a rubber consistency. Works just like the the expensive stuff you might buy for silicon molding.

You can also use dawn instead of cornstarch and Naptha to make it pourable but I have never tried them.

Must use 100% silicon caulk, its $4 at big box stores.

There are lots of YouTube videos on the subject. Most of them are for making molds but I have mostly used this process to make parts, like bung hole plugs.

I usually use lexan to make the mold as it does not stick to that.

@Ned can probably tell us what the chemistry is…

The flour and silicone rubber mixture sets to about car tire tread hardness or harder. The amount used probably affects the hardness greatly. I have considered using graphene or graphite to see what that is like.

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That’s definitely harder than I have make. Will give it a try.