How to cast gypsum or plaster stone

Please make sure you’re use castable plasted as a Plaster of Paris or silimar.

 

We recommend to use G-1 Release for all concrete and gypsum casting.

Add Pigment to your pre-measured water then add plaster.

We recommend approximately 9 US fluid once (.27kg) per 1 lb (.45kg) of dry gypsum.

  • Add water to the bucket
  • Add plaster slowly until plaster stop absorbing water
  • Let it stay in bucket 5-10 min (do not mix)
  • Mix carefully with hands and pour to the mold immediately
  • Shake mold from side to side to release an air pockets for face for the stone

 

If you’re use mechanical mixer add Citric acid to slow down the gypsum curing time.

  • Citric acid dosage rate 0.1-0.4%, maximum dosage 1%
  • Each 0.1% dose add 5-15 min. 0.4% in 50f/10c has working time about 1 hour

How to cast gypsum/plaster stone video.

 

Gypsum absorbs moisture, make sure you’re use a sealer if you’re apply gypsum stone for a kitchen back splash.

Sealers options: High Gloss Countertop Sealer or Polyurethane gloss sealer.

 

P.S. If you will color the gypsum stones with stains, do not use release agent. In general gypsum do not stick to the molds, but release agent helps to remove air pockets from the stone face. Release agent create a barrier between stone and stain. Stain will not get absorbed to the gypsum if release agent applied to mold. Release agent can be washed out with water prior coloring with stain if stone casted from concrete, but gypsum stone cannot be washed out with water.