Plaster of Paris: Good Idea/Bad Idea?

[blk n blu dream]

Can "Plaster of Paris" be used to cast a full mask sculpted from oil-based clay? I couldnt find the Ultracal 30... so I just wanted to check to see if PofP was a good idea?

 

[pirkleations]

Hey!


Plaster of Paris is just fine for casting from a oil-based clay master. It isn't as tough and long-lasting as Hydrocal or Ultracal 30, but it will do the job just fine for quite a few castings in latex before it starts showing wear.

I use it for my zombie masks and will be using it for my Pred-head mold.

I don't expect Plaster of Paris to yield tons of masks, but it is great for smaller runs of a masks before it wears out or begins to show cracks.

I certainly won't fault you for using it. If it works for me, it can work for you.


DangerDavey

 

[blk n blu dream]

Do you go with the directions on the bag for mixing?

 

[pirkleations]

Yes. I do follow the instructions on the bag...to a degree.

The main thing when mixing the water with the plaster is to have the water already in the mixing container before adding plaster. And here are a couple more professional tips...

-Sift(loosen) the plaster as you add it to the water. It will make the plaster stronger once it cures.

-For a faster curing/setting time, you can use warm water and a little salt in the mix

-Use metal floral wire cut to 1"-2" lengths as a depth gauge for how thick you want the plaster mold to be. Give them a light coating of vasaline and stick them into your sculpt like a pin cushion or acupuncture patient. Space them about every 4" from each other, or at key spots where plaster has to be thickest.

-Use burlap as a strengthening medium once you get an inital impression layer (about 1/2 inch)

Hope these tips help you out. I'm sure other members have more tips to contribute as well.

I've never had any problems with this method of mold-making yet.

Feel free to ask as many questions as you have to. That's what this place is for!! If you have any other questions that you think I can help with, email me!

Good Luck!!


DangerDavey

 

[blk n blu dream]

Thanks, that helped a lot.

Now about the burlap...

-Use burlap as a strengthening medium once you get an inital impression layer (about 1/2 inch)

Let's see if I am understanding this, once I get a 1/2 inch layer, I lay the burlap over it and then add more plaster?

Also what is a good thickness for a mold?

 

[NibsFlibble]

The burlap will help with strengthening the plaster mold and keep it from breaking. Use small strips of burlap, dip it in plaster, then place them at different angles all over the plaster (once you have about 1/2" of just regular plaster over your sculpt). You can even overlay the burlap strips if you want.

Then put a regular plaster layer on, then another layer of burlap strips, and so on until you reach the top of your pin depth markers.

Hope this helps!

 

[ScottAS]

For the burlap I pre-soak it so it doesn't act like a sponge. Then I dip the burlap into the plaster and apply it. With Plaster of Paris you want the mold to be very thick.