Morgan
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Problematic Idols
A friend wondered how to dissolve a plaster of Paris core on a mold he was working on and I ran across this story. Other than bicarbonates, would
anything else match the practicality of this method?
Dissolution of Plaster of Paris Idols into Solution of Ammonium Bicarbonate
https://youtu.be/66GrSp0a4no
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macckone
Dispenser of practical lab wisdom
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Not really, any bicarbonate would work.
Because the calcium carbonate is less soluble than the calcium sulfate and a minute amount of sulfate dissolves,
the reaction proceeds forward to calcium carbonate. If you heat the calcium sulfate to 150C it will lose water and become the powdery hemihydrate but
don't heat above 170C or you form the anhydrite. If he is doing slip casting, the heating step may be a more practical way to go. Depending on what
he is casting will determine the best method. If he is doing aluminum casting, the core will likely fall apart after the casting because the hot
aluminum will dry it to the hemihydrate and anhydrite. If he is doing metal then a pressure washer is likely to be far quicker.
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