Fill your mixing container with the water first and then sift/layer in your POP until it peaks slightly above the water. Let it sit there until the pop absorbs the water (some of the water will not absorb initially) probably about 10 minutes. As long as you don't mix the water/POP at this point, it won't activate. Be sure you have your mold (or whatever) ready by this point. Mix the pop and water gently, so you don't add more air bubbles than necessary. It should be smooth at this point. Pour. After you pour it, tap your mold a few times to force the air bubbles to surface. It'll start hardening and will turn very hot during this time. Next it will cool and will be slightly damp. Depending on the application, I usually let it sit after this for a couple of hours to dry.

You can vary your proportions of POP/water slightly. Less water and you'll have it hardening very quickly. More water, and it takes longer to set and usually starts weakening the end result.

Hope this helps. Let me know if something doesn't make sense.

If your question was what is POP, Plaster Of Paris.
Usually in an arts and craft store, however there is a more durable and stronger form at most pottery supply store, some hardware stores also carry.
Dena

I think Dena might be referring to Hydrastone.

It takes POP quite a while to cure. If it feels cold/clammy, it's not ready yet. When it's dry and feels more like room temp, it's ready.

And, since you're on this forum, be aware that POP & concrete don't work together unless the POP mold is coated with something that won't let it absorb the moisture from the concrete. Some professionals recommend 5 coats of real shellac (no synthetics). The shellac is a sealer -- mold release is used on the surface of THAT.

Sue

Thanks! I assumed you folks made your own POP mix for some reason.

No, we don't make our own. We're always in a HURRY to finish the mold and get to the CONCRETE (or tufa)! :-)

The concrete and tufa we DO tweak.

Sue