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Post by jweinpert on Oct 23, 2020 9:38:49 GMT -5
First time using this urethane.
Created a small 1 x 4 x 1/2" deep test casting using the 1:1 weight ratio. Put it in a pressure pot at 50 psi. Let it sit for 20 hours. When I pulled it out, it had a thin top layer of "white-something-or-other". Maybe it is air? The rest was super clear.
Tried it twice and it happened both times. Also, I poured a small thin layer on a granite inspection table and let it cure on its own. It too turned white.
What could cause this? What am I missing?
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Post by LawnBoy on Oct 24, 2020 22:22:30 GMT -5
First, clear slow will always foam in thin layers without pressure. It is the wrong product for this type of application, try an epoxy instead.
On your castings, I suspect moisture. This urethane is super sensitive to humidity, and that white foam is the result (assuming that there's not a ridiculous amount of air in the resin from mixing). Your air compressor could be dumping moisture into your pressure pot, or it could be dropping the temp in the pot and causing condensation. You have to be in a low humidity environment.
20 hrs. seems like a long time in the pot. You should be good after 3-5 hrs.
Good luck.
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Post by jweinpert on Oct 26, 2020 10:03:31 GMT -5
Understood ... thanks a bunch!
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