I did this at TechShop Menlo Park. http://www.techshop.com

To save yourself a few dollars, you can re-use old plaster molds to make fresh plaster powder.

Step 1: Find cardboard and/or thin plastic sheetss

Dig for whatever you can use to wrap the old plaster chunks and prevent the dust you'll be creating from flying around.
<p>Landfill sites refuse drywall and plaster because as it decomposes, hydrogen sulfide gas is released. So, re-use it by crushing it and reheating it in a 325 degree F oven overnight, to drive out the hydrated water.</p>
<p>how long does the plaster have to be in the oven for? </p>
<p>Hours and hours. 6 to 8 of them. It's a reminder why cements and plasters are environmentally costly.<br><br>I built a solar oven to do the job. One small batch of plaster at a time, but no energy cost.</p>
It will also accelerate the set of fresh plaster, which may be convenient or not.
I have just had a look at your other instructables and I see you have made a furnace for lost wax casting, you might be intrested in what I want the brick grog for, I'm doing an instructable for making your own crucibles might be useful for you ;-)
further to my earlier comment, I took an old shirt and ripped it so it was square wrapped up some old pieces of garden pot and smashed away with my club hammer and it worked great. <br> <br>so the answer is yes this can be used to make your own grog, hard work with a club hammer though, but it works.
this seems like a good method for making your own grog for ceramics from brick or old garden pots. <br> <br>once its all smashed up you could pop it in to a ball mill for a finer powder
Don't you need to heat it to reactivate it? If I recall, it's to about 350F...
yes, to make it back into usable plaster you would need to heat it to extreme temperature to drive out all the water, even that chemically bonded to the gypsum. I don't know the temp. What he is doing here is adding it to new plaster, basically as an inert filler.
Brilliant! I never knew you could do that.

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