How to Mix Plaster for Sculpture

Last Updated: January 19, 2024

Mixing plaster with a "rule of thumb" method doesn't require precise measurements. Sculptors typically use this method to mix small to moderate amounts of plaster (less than five gallons/22 liters) for molding and casting. The same instructions apply to all standard gypsum plaster products, such as Plaster of Paris, Hydrocal, Densité, etc.

Steps

Download Article

{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/d\/da\/Mix-Plaster-for-Sculpture-Step-1.jpg\/v4-460px-Mix-Plaster-for-Sculpture-Step-1.jpg","bigUrl":"\/images\/thumb\/d\/da\/Mix-Plaster-for-Sculpture-Step-1.jpg\/aid42718-v4-728px-Mix-Plaster-for-Sculpture-Step-1.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"<div class=\"mw-parser-output\"><p>License: <a target=\"_blank\" rel=\"nofollow noreferrer noopener\" class=\"external text\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">Creative Commons<\/a><br>\n<\/p><p><br \/>\n<\/p><\/div>"}

Remember it is 1/3 plaster, 1/3 silica flour and 1/3 water. Experience is the best guide here, so as a beginner you will just have to make your best guess, then mix extra to be sure you have enough. Use commonsense. ^{[1]
X
Research source}
{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/a\/ae\/Mix-Plaster-for-Sculpture-Step-2.jpg\/v4-460px-Mix-Plaster-for-Sculpture-Step-2.jpg","bigUrl":"\/images\/thumb\/a\/ae\/Mix-Plaster-for-Sculpture-Step-2.jpg\/aid42718-v4-728px-Mix-Plaster-for-Sculpture-Step-2.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"<div class=\"mw-parser-output\"><p>License: <a target=\"_blank\" rel=\"nofollow noreferrer noopener\" class=\"external text\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">Creative Commons<\/a><br>\n<\/p><p><br \/>\n<\/p><\/div>"}

^{[2]
X
Research source}

Advertisement
{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/b\/bd\/Mix-Plaster-for-Sculpture-Step-3.jpg\/v4-460px-Mix-Plaster-for-Sculpture-Step-3.jpg","bigUrl":"\/images\/thumb\/b\/bd\/Mix-Plaster-for-Sculpture-Step-3.jpg\/aid42718-v4-728px-Mix-Plaster-for-Sculpture-Step-3.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"<div class=\"mw-parser-output\"><p>License: <a target=\"_blank\" rel=\"nofollow noreferrer noopener\" class=\"external text\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">Creative Commons<\/a><br>\n<\/p><p><br \/>\n<\/p><\/div>"}

A a standard two-gallon (7.5 liter) plastic bucket is a good container. The amount of water should be approximately one third the total amount of mixed plaster/silica you estimated in Step 1. ^{[3]
X
Research source}
{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/7\/73\/Mix-Plaster-for-Sculpture-Step-4.jpg\/v4-460px-Mix-Plaster-for-Sculpture-Step-4.jpg","bigUrl":"\/images\/thumb\/7\/73\/Mix-Plaster-for-Sculpture-Step-4.jpg\/aid42718-v4-728px-Mix-Plaster-for-Sculpture-Step-4.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"<div class=\"mw-parser-output\"><p>License: <a target=\"_blank\" rel=\"nofollow noreferrer noopener\" class=\"external text\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">Creative Commons<\/a><br>\n<\/p><p><br \/>\n<\/p><\/div>"}

Gradually pick up handfuls and sift the powder through your fingers. This will break up any clumps, letting the powder fall into the water. Work quickly, but avoid dumping the plaster into the water. Don't stir or mix the combined water and plaster/silica. ^{[4]
X
Research source}
{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/b\/b0\/Mix-Plaster-for-Sculpture-Step-5.jpg\/v4-460px-Mix-Plaster-for-Sculpture-Step-5.jpg","bigUrl":"\/images\/thumb\/b\/b0\/Mix-Plaster-for-Sculpture-Step-5.jpg\/aid42718-v4-728px-Mix-Plaster-for-Sculpture-Step-5.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"<div class=\"mw-parser-output\"><p>License: <a target=\"_blank\" rel=\"nofollow noreferrer noopener\" class=\"external text\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">Creative Commons<\/a><br>\n<\/p><p><br \/>\n<\/p><\/div>"}

Watch for it to start sinking slowly. Eventually some of the powder will stay on top of the water. As you add more plaster, distribute it to areas that still have water on top.
{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/a\/a4\/Mix-Plaster-for-Sculpture-Step-6.jpg\/v4-460px-Mix-Plaster-for-Sculpture-Step-6.jpg","bigUrl":"\/images\/thumb\/a\/a4\/Mix-Plaster-for-Sculpture-Step-6.jpg\/aid42718-v4-728px-Mix-Plaster-for-Sculpture-Step-6.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"<div class=\"mw-parser-output\"><p>License: <a target=\"_blank\" rel=\"nofollow noreferrer noopener\" class=\"external text\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">Creative Commons<\/a><br>\n<\/p><p><br \/>\n<\/p><\/div>"}

The surface of the combined water and plaster/silica should be mostly grayish in color, with some areas of white dry powder. Don't mix it yet! ^{[5]
X
Research source}
{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/8\/81\/Mix-Plaster-for-Sculpture-Step-7.jpg\/v4-460px-Mix-Plaster-for-Sculpture-Step-7.jpg","bigUrl":"\/images\/thumb\/8\/81\/Mix-Plaster-for-Sculpture-Step-7.jpg\/aid42718-v4-728px-Mix-Plaster-for-Sculpture-Step-7.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"<div class=\"mw-parser-output\"><p>License: <a target=\"_blank\" rel=\"nofollow noreferrer noopener\" class=\"external text\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">Creative Commons<\/a><br>\n<\/p><p><br \/>\n<\/p><\/div>"}

Let it stand during the time that you make any final preparations for your project. If you are molding or casting with the plaster, this is a good time to double-check that you have applied the proper release agent to your pattern or mold.
{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/2\/28\/Mix-Plaster-for-Sculpture-Step-8.jpg\/v4-460px-Mix-Plaster-for-Sculpture-Step-8.jpg","bigUrl":"\/images\/thumb\/2\/28\/Mix-Plaster-for-Sculpture-Step-8.jpg\/aid42718-v4-728px-Mix-Plaster-for-Sculpture-Step-8.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"<div class=\"mw-parser-output\"><p>License: <a target=\"_blank\" rel=\"nofollow noreferrer noopener\" class=\"external text\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">Creative Commons<\/a><br>\n<\/p><p><br \/>\n<\/p><\/div>"}

Plaster reaches a high temperature as it reacts chemically with the water and can cause serious burns!. Use a wooden spoon or similar instrument as one would use an egg beater: Reach down to the bottom of the container and use a side-to-side movement like an exaggerated "hello" wave. ^{[6]
X
Research source}
{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/1\/1a\/Mix-Plaster-for-Sculpture-Step-9.jpg\/v4-460px-Mix-Plaster-for-Sculpture-Step-9.jpg","bigUrl":"\/images\/thumb\/1\/1a\/Mix-Plaster-for-Sculpture-Step-9.jpg\/aid42718-v4-728px-Mix-Plaster-for-Sculpture-Step-9.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"<div class=\"mw-parser-output\"><p>License: <a target=\"_blank\" rel=\"nofollow noreferrer noopener\" class=\"external text\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">Creative Commons<\/a><br>\n<\/p><p><br \/>\n<\/p><\/div>"}

When thoroughly mixed, the plaster is ready to use in your project. ^{[7]
X
Research source}

Community Q&A

Search

Add New Question

Question

Can I use Plaster of Paris to mold my face?

Community Answer

It would be a safer idea to make a silicone mold of your face first, then to fill that mold with plaster, if your plan is to make a casting. If you use plaster to make a mold, and something goes wrong, you could potentially hurt or suffocate yourself. Silicone, though not completely safe to use, is safer, and could be peeled away from skin much more easily. Please be sure to use silicone that is formulated for mold making, and for prolonged contact with skin. If you are serious about facial mold making, contacting someone who specializes in the field would be a great way to find out how to safely use plaster for this purpose.

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 2 Helpful 12
Question

Can a model be carved out from a whole solid square made of plaster of Paris?

Community Answer

Yes, but you have to be careful, as the plaster of Paris square may break, and the sculpture will not be very durable.

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 2 Helpful 5
Question

Can plaster of Paris be used for an outdoor sculpture?

Community Answer

It can, but the sculpture will not be very durable and could be damaged by weather conditions.

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 0 Helpful 6

See more answers

Ask a Question

200 characters left

Include your email address to get a message when this question is answered.

Submit

Video

Tips

The water temperature makes a difference. Hot water will speed up the setting of the plaster; cold water will slow it down. Depending on your project, you may want to use either hotter water for faster turnaround when pouring molds or cooler water for a slower process.

Thanks
Helpful 30 Not Helpful 12
Plaster tends to leach moisture from skin. You may want to use hand lotion after mixing. Almond oil is excellent, as are your normal moisturizers.

Thanks
Helpful 24 Not Helpful 11
You can use any movement you like for mixing the water and plaster, but avoid whipping air bubbles into the mix. Bubbles can be detrimental to the surface of your mold or casting.

Thanks
Helpful 18 Not Helpful 8

Show More Tips

Submit a Tip

All tip submissions are carefully reviewed before being published

Submit

Thanks for submitting a tip for review!

Warnings

Avoid getting plaster on clothing or other items of value. It can be very difficult to remove from fabric and other porous surfaces. However, if there is an accident and it spills on fabric, it's worth trying to remove it. Don't automatically deem any soiled item ruined.

Thanks
Helpful 9 Not Helpful 9
Always wear a dust mask as the inhaled plaster dust particles will mix with fluid in your lungs and harden there. This is very dangerous and easily avoided.

Thanks
Helpful 0 Not Helpful 0
NEVER use hands to mix plaster or apply plaster to set directly on any body parts or skin- serious burns have occurred resulting in amputation of fingers and limbs.

Thanks
Helpful 0 Not Helpful 0
Never pour plaster down a sink or other drain. It can solidify and ruin the plumbing. Dispose of unused plaster in the trash. Rinse wet plaster off hands in a bucket of water before washing them in the sink.

Thanks
Helpful 0 Not Helpful 0

Things You'll Need

Plaster (dry powder)
Source of clean water
Plastic bucket or other flexible mixing container
Project needing mixed plaster

You Might Also Like

[1]

[2]

[3]

[4]

[5]

[6]

[7]

Log in

How to Mix Plaster for Sculpture

Steps

Community Q&A

Video

Tips

Warnings

Things You'll Need

You Might Also Like

References

About This Article

Did this article help you?

About This Article

Quizzes

You Might Also Like

Featured Articles

Trending Articles

Featured Articles

Featured Articles

Watch Articles

Trending Articles

Explore Categories