Plaster of Paris and Plaster

[minkster]

This may seem like a dumb question, but I own both plaster of paris and plaster. On the clay molding I made (to vacuum form eventually) I want to make a plaster cast. My question is...is plaster of paris the same thing as plaster? In that case when making my plaster cast, should I use the plaster that came in a tub or mix up the plaster of paris with water? Which one is easier for people who have done this job before? Thanks-minkster

[geekbait111]

(yes I know wrong spelling) accourding to studiocreations thingy it says this:

Here is a bag of plaster. Actually this is "PLASTER OF PARIS". I do not recommend "Plaster of Paris" for casting because it is brittle and not too strong. Use "ULTRACAL-30" or "HYDROSTONE". These can be bought at a Gypsum Supply House. Look in the Yellow Pages for an address. Ceramic supply houses carry gypsum products also.

so plaster of paris is not good.
here's the plaster thing that's in the sticky (sort of)
http://www.studiocreations.com/howto/pl ... index.html

[minkster]

Hmm..interesting...thanks for showing me that. I would think plater of paris would be strong enough though...I mean I'm not making a statue of some sort. Just a flat clay molding into a plaster cast. I just looked through one of my old pm's from turbo tax and he said to first put plaster of paris on it, fill the cast with plaster, and then sand and bondo it up to be ready to vacuum form. Hmm...I'm guessing if I use both it would be strong enough. So I guess plaster and plaster of paris are slightly different then.

[marshallh]

Well, it depends on what you're using it for. For the above quote, apparently plaster isn't good for planting pots. But there should be no problem making a cast/mold with it.