steve99 wrote:

I've just bought 20 kg of Victor 'Dental Plaster' which is 100% pure Calcium Sulphate Hemihydrate, which I have learnt is aka Plaster of Paris.


If you can be bothered I think you can add cement by weight to create a mix with a greater strength.

As an example, DynaPlast (psi 12,000) is made up of:

Calcium Sulfate Hemihydrate (Plaster of Paris) at >80%
Portland Cement at < 20%
Crystalline Sillica at less than 0.5%

according to the MSDS. I think I read somewhere that the Cement is actually 9% -- and at that concentration, it sets up very quickly (which I've posted about elsewhere). However you might try adding 5% Cement and see how that goes. There's a chance you'll be throwing good money after bad, but I think you'll end up with a useable mix after some experimentation.

Regards,

Ian P.
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