Introduction: Plaster Casting - Multi Part Molds

This slide show is going to take you through the process of duplicating a sculpture using a multi part plaster mold. In this case, it was a clay cow getting duplicated in a soft foam urethane. The materials needed include:

  • Plaster
  • Plaster bandages, fiberglass, hemp, burlap, or horsehair
  • Disposable gloves
  • A mixing bucket
  • Trash bags to line the bucket for mixing up plaster
  • Aluminum cans
  • Scissors
  • Duct tape
  • A screwdriver
  • Shellac
  • Chip brushes
  • Pam, mold soap, mold release, floor polish wax, Murphy's oil soap, or liquid vaseline to use as a mold release

This sculpture was made by Liz, another RISD student. This project was made possible due to the herculean efforts of Edmund Earle (kind of), Damian VanCamp, Lauren Kaufmann, and the brave RISD janitorial staff.


coweja made it!(author)2016-11-17

I see this video or instructable is from 2007, but I have been looking for DIY curved pieces into a mold, but this is actually the first one I found. This video failed to show the final product, maybe because there was none but failed to say so too. This was done by a RISD student? I hope the student graduated, with honors. I miss the beautiful Rhode Island. Videos like these are inconclusive and shouldn't be published. thank you

Miss+Cabbit made it!(author)2012-07-31

This is purely brilliant and fun. Thanks for the inspiration.

h3llo41 made it!(author)2009-03-23

i made a mold with light plaster (i didnt know what to buy), and it break when i try to take it out, i might have bout the wrong one. is light plaster the same plaster as used in here?

zoe-australia made it!(author)2009-01-05

Hi, cow looks great! next time try embedding some hessian(old jute bagging) or shadecloth , or cut up pieces of flyscreen into the plaster and it helps to strengthen the plaster mold. If you cut strips of old hessian/shadecloth/fibreglass flyscreen, and dip it into the plaster then drape it across the mold sections it helps. For curved shapes, using a triangle shaped piece of mesh fabric works best as it will wrap around a curved shape better. Love the idea of using aluminium cans for shims, great way of avoiding thick shims distorting the final product by making thick ridges on the joints, that have to be sanded down. If you keep your shellac mix in a wide mouth coffee jar with a screw top plastic lid then any leftovers can be kept for future projects. Just make sure the thread of the lid and jar are wiped clean before closing otherwise it will stick so hard you will be cursing when you next try to open the jar. Should this happen use hot water on the lid to soften it and then get a good grip on the lid and strain yourself to open it. This is when a srong handed man is an essential in the workshop! LOL.

Big+Bubba made it!(author)2008-01-25

Great! I love cows. Me and my dad are obsessed with them and always saying "Moo!". I going to make him one of these!

Patrik made it!(author)2007-11-30

There's some seriously missing steps here...

For starters, how the heck do you get your plaster mold off your clay original, especially the udder part, which seems to stick out in all directions??

Garth+Knight made it!(author)2007-11-30 . . (snicker)

T3h_Muffinator made it!(author)2007-11-30

What happened to the revolution?

Garth+Knight made it!(author)2007-12-01

realty happened. (work)

T3h_Muffinator made it!(author)2007-12-01

v_v That's alright, though! *pat pat*

Patrik made it!(author)2007-12-01

I'd hate to see what would have happened if I had said "teats"...

bofthem made it!(author)2007-12-01

Since the final casting was in soft foam, undercuts weren't a giant concern in this model. I just destroyed the clay model upon demolding. It just fell apart. It's clay, not depleted uranium. It took some cleaning, but every piece of clay came out of the mold.

Patrik made it!(author)2007-12-01

That's what I assumed, but it would ave been nice to show some pictures of that part as well - or at least *mention* that's what you did.

I can just imagine someone trying to follow your instructions using a piece that they cannot or do not want to destroy...

trooperrick made it!(author)2007-12-01

I like it. But if you could, for a suggestion, to put up an instructable of how you cast something with the mold.

T3h_Muffinator made it!(author)2007-11-30

Jeez, man. You've got some serious molding talent...

%21Andrew_Modder%21 made it!(author)2007-11-30

..good instructable, but i honestly dont like the slide show at all.

GorillazMiko made it!(author)2007-11-30

ooooh. cows. :)

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Bio: I'm M@. If you know Prototype This, TechShop, The Best of Instructables, Show Me How, or AVPII: Requiem, you've seen some of my ... More »
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