Plaster of Paris question

It should set in about the same time as the plaster cloth - too fast!

For anything but a very small scene, you will spend more time mixing up batches and, in between, trying to clean the set plaster out of the mixing bowl.

If you have much to do, a slow setting plaster such as Structolite or 45 minute drywall compound in powdered form would be easier to work with.

For any plaster, you want a commercial grade paper towel (the rough brown ones), not the kitchen type.

Jim

Jim,

Thanks for the tips. I guess that is one more thing I can toss. I have been remodeling 60% of my first floor of my home, I still have half a sack of 20 and half a sack of 40 minute mud left over.

Can you make it soupy and coat the paper towels with it?

Ted

Ted..Plaster of paris is excellent for use in rock molds!

Bob

Ted,

That drywall compound should be good for the paper towels. When the paper towel layer has set, go back with another coat of compound over everything for additional strength.

As Bob said, save the plaster for rock castings.

Jim

Jim,


Any issues getting the plaster of Paris to release from the rock molds? I was spraying the molds with soapy water last year, but that was with 20 min drywall mud.

Ted

No issue at all, let the P of P cure up until it seems to be almost setting, then plop it on the spot you want the rockwork to be and hold it in place really making sure it is mushing into the surface until it sets up...the rubber mold will peal off the cured P of P no problem. Doing rockwork using molds is pretty easy and very gratifying once you get the hang of it. It's cheap too!

Bob

Ted,

Bob's method is one way of doing it. If you have trouble with sticking, let the casting really set up solid in the mold. Then peel carefully. You can either apply them semi-soft, as Bob does, or hot glue them in place when they are dry. Usually, I just spray some "wet water" in the mold before pouring the plaster.

I think you'll find the P of P easier to work with in molds than the drywall compound. It can be done with compound, but setting time is long and the castings aren't as tough.

Usually, it's P of P or Hydrocal for castings and the slow setting stuff for the basic scenery shell.

Jim

Bob & Jim,

Thanks for the help!

For all the users of plaster cloth out there ,if you don't do it this way you don't know what your missin,Uh besides having it all over yourself and everywhere else for that matter.

Take your cloth and lay it where you want it.
If you have a soft structure underneath(Like card board or foam) shape it and pin it in place with straight pins.

If you have a plywood structure get out the staple gun and do the same thing.

Once your plaster cloth is how you want it get yourself a spray bottle fill it with water and add a couple of drops of Dove.
I like the spray bottle with an adjustable tip .The fixed ones just don't put enough water out the way I like it.

Spray your plaster cloth and let it set in place.Believe me once it's painted you'll never see those pins or staples.

You can even plete the cloth to simulate erosion kinda like a washboard effect.

It doesn't take much water to get this stuff to set and this way you don't have all the mess.

David