# Plaster of Paris



## chawalang (Nov 1, 2018)

Would any one know once plaster of paris dries how much it would weigh, so if I have a 25lbs bag and mix it with water how much will it weigh once dry.

Thanks!


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## Van (Nov 1, 2018)

It depends on how you mix the Plaster. A small bit of water will be lost in the form of steam. Most of the water will be absorbed into the structure of the, now, hydrated plaster.

If you use a gallon of plaster and add 3 quarts of water then your resulting plaster, when set, is going to weigh, the weight of the plaster + the weight of the water or 1 pound per pint, in this case six pounds.

Basically just don't expect to lose any water weight once the plaster sets.Also because the water is literally incorporated in the chemical structure of the plaster it doesn't increase in volume, significantly, when mixed.


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## chawalang (Nov 1, 2018)

So with water a 25 pound bag would then weigh 31 pounds with water added?


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## Van (Nov 1, 2018)

chawalang said:


> So with water a 25 pound bag would then weigh 31 pounds with water added?



Plaster of Paris is typically mixed by volume not weight. So how ever many gallons of plaster you are mixing + however many gallons of water you are using. I have no Idea what a gallon of dry plaster weighs. but one gallon of water is, for all intents and purposes 8 pounds. <All the world round a pint is a pound> 

You usually use a 1:.70 Plaster to water mix. you can call it .75.
So, 1 gallon of plaster mixes with 3 quarts of water.


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