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Plaster Retarder

Ed asks:

“I am looking for a retarder to slow down the hardening of Hydrocal plaster. What do you folks find that works and is readily available?”

4 Responses to Plaster Retarder

  • Dale says:

    Not much, really. If you are not able to complete the work in the 20-25 minute (typical) set-up time, perhaps you should work in smaller areas. A looser mix of Hydrocal will take longer but will be harder to work with unless you’re just filling a mold.

    A small amount of time can be gained by working is a cooler environment as heat will tend to dry things faster.

  • Joe Lovell says:

    Hi Ed
    Hopefully this helps you, I myself use drywall joint compound powder mixed with water, it comes in bags of 20min to 90min set time can be found in home improvement stores it’s good stuff and it doesn’t Crack. Good luck, Joe

  • Frank Miles says:

    I use casting plaster and I use a fine serve. When I mix it I also put in a few drops of fish washing liquid. This appears to give me more time to apply it. If the mix starts to harden I add a bit more water, it softens then I can finish using all the mix. Hope this was helpful.

  • David Stokes says:

    Make smaller batches. Plaster is designed to set in a given time frame. To slow hardening will weaken the plaster.

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