How to Mix Plaster for Sculpture

PDF download Download Article
PDF download Download Article

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

PDF download Download Article
  1. 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]
  2. [2]
    Advertisement
  3. 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]
  4. 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]
  5. 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.
  6. 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]
  7. 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.
  8. 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]
  9. When thoroughly mixed, the plaster is ready to use in your project. [7]
    10. Advertisement

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
      Advertisement

      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 31 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 25 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 19 Not Helpful 8
      Show More Tips
      Submit a Tip
      All tip submissions are carefully reviewed before being published
      Name
      Please provide your name and last initial
      Submit
      Thanks for submitting a tip for review!
      Advertisement

      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
      Advertisement

      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

      How to
      Do Ceramic Sculpture
      How to
      Sculpt Clay
      How to
      Sculpt a Face
      How to
      Make a Soap Carving
      How to
      Make a Sculpture
      How to
      Make Mannequin Heads
      How to
      Scrimshaw
      How to
      Sculpt
      How to
      Sculpt With Concrete
      How to
      Make a Latex Mold
      How to
      Make a Rubber Mold
      How to
      Life Cast
      How to
      Use a Chisel
      How to
      Craft Wax Hands at Home
      Advertisement

      References

      1. ↑ https://www.firstpalette.com/craft-recipe/mixing-plaster-of-paris.html
      2. ↑ https://ceramicartsnetwork.org/daily/pottery-making-techniques/making-ceramic-molds/how-to-mix-plaster-for-ceramic-molds/
      3. ↑ https://snapguide.com/guides/mix-plaster-for-sculpture/
      4. ↑ https://juxtamorph.com/the-plaster-faq-working-with-plaster/
      5. ↑ https://ceramicartsnetwork.org/daily/pottery-making-techniques/making-ceramic-molds/how-to-mix-plaster-for-ceramic-molds/
      6. ↑ https://juxtamorph.com/the-plaster-faq-working-with-plaster/
      7. ↑ https://ceramicartsnetwork.org/daily/pottery-making-techniques/making-ceramic-molds/how-to-mix-plaster-for-ceramic-molds/

      About This Article

      In other languages
      Thanks to all authors for creating a page that has been read 243,817 times.

      Did this article help you?

      Advertisement