Which plaster is best for casting as many latex masks as possible?

I am wondering which plaster I should get to make as many copies of my giant monster torso mask as possible. I heard of ultra cal and hydro cal but also plastercast which a distributor near me sells. And I read a book by Russ Adams but he said the casting from a ultra cal mild is limited and the mold  gets worse every new casting. But I would have many ideas for several masks so I wanted to ask if there’s a special preferred plaster or a sealing thingy to make the mold more durable. 

Thank you so much and a happy new year 🥳 

Best Answer


  • Okay and can you also create many copies? Because I heard that if you would use pottery plaster you can do 10 copies and with ultra cal (or maybe hydro cal too) much more because it’s designed for mass production. Is this true and what do you think about plastercast?
    thank you so much Chris 
  • Chris EllerbyChris Ellerby Los Angeles Admin
    I've never used a product called "plastercast" I only really use Ultracal and Hydrocal when doing stone molds. (which I don't do too often any more)

    You can get more than 10 castings out of a Ultracal or Hydrocal mold, depending on how you take care of it, how it's designed, and the nature of the thing you molded.

    If your original source object (sculpt, etc) does not survive the mold making process it is usually a good idea to first cast a master casting out of your mold that you can mold again for future generations of molds.  Since molds don't last forever it's always a good idea to have a master.

  • Oh okay thanks!!
  • Oh and which material would you use for the master ? Which would be easy to cast in the hydro cal mold and easy to mold someday.

  • Chris EllerbyChris Ellerby Los Angeles Admin
    edited January 2020
    If the mold is flexible (silicone jacket etc) you would want a nice rigid master, usually in something like a urethane resin.

    For a rigid stone mold you would want your master in something with a bit of flex to it so it can demold easy without damaging your mold.  Any rubber that can hold its form (so it can serve as a master for re-molding) but is soft enough not to damage the stone would be fine.
  • Okay thanks and would you have any material for casting in plaster in mind ? Ecoflex 🤣 maybe ?
  • Chris EllerbyChris Ellerby Los Angeles Admin
    What material you pick can change based on what your mold and cast form are, but if you have an example you could potentially send a photo to a material supplier like Smooth-On to ask them which of their materials would work for that situation.  For stone you want something with a bit of give, and for its role as a master casting you want dimensional stability.  Many materials will shrink as they cure.

  • Okay thanks, I will when I’m at this stage. I wasn’t sure if silicones or other materials work well in stone mold
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