Plasticine sculpt and plaster question

[Sonnenschein]

I have a question for you sculptors.

 

Let's say I have a plasticine sculpt, and I want to encase it in plaster. It it was flat, I'd just pour plaster over it.

 

What are my possibilities? Brushes? I dont want to destroy the sculpt.

 

Thanks!

 

[pandatrooper[TK]]

What do you mean by encase it? Do you want a thin coating or do you want a negative mold?

[Sonnenschein]

yeah, a negative mold in the end, a thin coating would suffice. Ijust to protect the surface details. I know who to do the rest of a mold

 

Hi Terry! Long time no see!

Edited April 14, 2015 by Sonnenschein

[Sonnenschein]

It's about this sculpt. 

------------

 

I know how to apply plaster to the bib part, it's the ribs that worry muy. So I guess I'd use soft brushes

Edited February 21, 2021 by gmrhodes13
link not working, removed gmrhodes13 2021

[Sonnenschein]

I think I just answered my own question. But I'm open to more suggestions!

[gazmosis[501st]]

whichever plaster you use will likely build a lot of heat and melt the sculpt material and make it really hard to get out of the mold undamaged. Can you use silicone as your mold making material?

[pandatrooper[TK]]

I was going to suggest the same thing. Don't worry about protecting the sculpt. Just use silicone as a mold. You could do a mother mold on top. I've used smooth on silicone and then plastipaste as the mother mold.

[Sonnenschein]

unfortunately, it needs to be plaster. No problems with the sculpt being destroyed.

 

I made some sucess with flat sculpts. 

[Bone[501st]]

Hi Karin!

 

It is not necessarily a question of "how", but of "what".

To use soft brushes is an excellent idea, but if the plaster is as thick as you would normally make it to just pour a mold, the bristles will clog up and will be of much use as a piece of wood.

You have to make the plaster rather runny to brush it on.

But then you are going to have a problem with your positive, as the plaster runs down and merely creates a puddle at the bottom.

The best way, imho, is to tilt your positive and rotate it while brushing the plaster on.

 

On the other hand, if you can find a really thick soft brush (like a cosmetic brush used for blushing) and clean it in water after every third or fourth stroke you could use plaster that is thicker ...

 

I hope that made sense ... 

[walt[501st]]

What I have done is pour the plaster over it when dry remove the mold Let cure for at least a week then seal the negative with a silicone spray and pour plaster it that. Let dry and brake the negative. You now have a plaster copy. But the best way as panda said. Smooth on is the way to go

[Bone[501st]]

Karin is going to fill the mold with latex, so the mold has to be made out of plaster ...

 

A silicone mold just simply wouldn't work, because it would take ages for the latex to dry.

And the plaster mold also can't be sealed with silicone spray, because the plaster is supposed to absorb some of the water that is in the liquid latex and therefore has to be porous.

[Sonnenschein]

yeah, Bone is right.

 

I'll just put the sculpt into the freezer for an hour. Problem solved!

 

 

Thanks for your input, guys!

[Bone[501st]]

Now that's a smart idea!

[Ruste dowg]

I sculpt in plastercine and have used the freezer to harden it up and it works well...just make sure it is smoothed out as best you can and chill it for a while before the plaster goes on...