plaster/clay mold

[smilie120]

So...I read somwhere that when youve finnished your clay model, you can create a mold by using plaster?
I need theese questions answerd if im going to attempt this.

1. Would I have to pepare the clay before painting it with plaster?
2. How do I create a split line for the plaster?
3. How much would clay cost, I need enought to fit my head.
4. What material would be suitable to make a cast from the mold? (poly-uerathane or w.e?)
5. Is there any other way you can make a mold from a clay sculpt?


So can anyone help me with these?

many thanx
--smiliee120

 

[josiahpeters]

So...I read somwhere that when youve finnished your clay model, you can create a mold by using plaster?
I need theese questions answerd if im going to attempt this.

1. Would I have to pepare the clay before painting it with plaster?
2. How do I create a split line for the plaster?
3. How much would clay cost, I need enought to fit my head.
4. What material would be suitable to make a cast from the mold? (poly-uerathane or w.e?)
5. Is there any other way you can make a mold from a clay sculpt?
So can anyone help me with these?

many thanx
--smiliee120

1. Nope, I just brushed the plaster right on to the clay.
2. I would suggest using a very thing metal. Flashing for ventilation systems is what I'm using. I'm not sure the best way to describe where to create the split lines in the mold.
3. I got cheap clay, $7.50 for 25lbs. It took all of my 25lbs of clay to sculpt my helm. More if you aren't sculpting on a head.
4. I'm using fiberglass to cast from my molds.
5. You could use a silicone product, most people do

 

[Sigma LS]

5. I agree

Silicone is the only way to go if you have any undercuts in your model.

 

[smilie120]

So I can use simple wall plaster, what comes in a white powder and you have to add water to it? Or do I have to use some silicone product for the first coat? How can I stop the plaster sticking to the clay? and finaly how many molds could i make out of a plaster cast?

 

[josiahpeters]

So I can use simple wall plaster, what comes in a white powder and you have to add water to it? Or do I have to use some silicone product for the first coat? How can I stop the plaster sticking to the clay? and finaly how many molds could i make out of a plaster cast?

The plaster I'm using is called HYDROCAL. its very fine and is super strong. You do not want to use wall caster, at the very least use a "CASTING PLASTER." A 50lb bag of hydrocal cost me $25.

http://www.plaster.com/HYDROCAL.html

You should be able to make many castings from a plaster mold if you are careful and use a proper mold release.

 

[smilie120]

all this seems cheaper than a pep helm. 1 More thing sorry. Where can I buy a polystyren head or somthing to work on top of?

 

[optimusaint]

all this seems cheaper than a pep helm. 1 More thing sorry. Where can I buy a polystyren head or somthing to work on top of?

any beauty supply place. hairdressing students use them to put wigs on when they learn to cut hair.