How to Cast Mosaic Stone Mold

How to Cast Mosaic Stone Mold

Always apply release agent to your mold prior casting concrete.


Mosaic mold average casting weight is about 10 lbs. (4.5 kg.)

1 x 2 cement to filler mix as follows: (you can also mix 1-part Portland cement to 3 parts sand (filler), plasticizer and water has to be re-calculated by cement weight)

3.33 lbs. (1.513 kg) Portland cement (white for light stone colors, gray for dark stone colors)

6.7 lbs. (3.35 kg) Sand (20-30 mesh recommended) (silica sand or "all-purpose" sand works great)

0.66 lbs. (300 gr) Water (3.33 lbs. of cement x .20) (recommended water to cement ratio 20-30%) (Lower water ratio if your mix to liquid). If your send is wet, add 50% of pre-measured water, mix concrete than add remaining water if needed.

0.033 lbs. (15 gram) Super-plasticizer (3.33 lbs. (1.513 kg) of cement x 1%)

For best result always add dry pigments to your mix prior adding a water. Mix concrete with pigment and additives few minutes, then add water (mix at least 3-5 minutes). You can also add Super plasticizer to the water 10-15 minutes prior casting, then mix with dry ingredients.

Please note: Concrete minimum mixing time 3 minutes (it takes few minutes until Super Plasticizer absorbs to cement and start reaction)

To color different molds sections, brush color over the molds selected sections, then cast the concrete.

Cover the mold with plastic. Remove the stone from the mold in 12-24 hours.


P.S. 871 mold casting weight 12 lbs. Plasticizer and water has to be re-calculated by cement weight


Mosaic Stone molds casting with gypsum


Use castable gypsum/plaster as "Plaster of Paris"

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

  1. Add 64 oz (1 liter) water to the bucket
  2. Add plaster slowly until water stop absorbing the plaster, let it set for 3-5 minutes.
  3. Mix carefully with hands or add citric acid to prolong gypsum set time and mix with mechanical mixer. Citric Acid dosage rate 0.1-0.4%, maximum citric acid dosage 1%. Each 0.1% dose adds 5-15 min of set time.

    0.4% in 50f/10c set time about 1 hour

  4. Cast to mold, shake mold from side to side carefully, let it cure.

Super plasticizer can be added to gypsum/plaster to make the gypsum stone stronger. Super plasticizer recommended dosage rate 0.25% by gypsum/plaster weight.

Gypsum/plaster stone can be carefully removed from mold in 30 minutes.


How to cast gypsum or plaster stone video