Pouring Gypsum Molds

Although gypsum is not found naturally in Japan, over the past 100 years Japanese plastering has adapted the use of gypsum plasters and gypsum molds.  The following are examples of poured gypsum molds featured at the Kyoto Plastering Institute.

 

 An imprint

  Student's mold

The following is a description of pouring simple gypsum molds.  In subsequent posts, more elaborate moldings will be discussed:
1. Create the form with clay. 

 In this case, a clay mixed with oil is used. 

 The oil inhibits the clay from drying and provides easier release from the silicone mold.

2. Spray the clay mold and board with a lacquer spray to improve release.

3. Cover the clay mold with a silicone gel that hardens with the addition of a hardener.

 Silicone

 Hardening Agent: Add half a bottle of hardening agent to one can (1kg) of silicone

 Mix thoroughly

 4. Cut the edges of the silicone mold for easy release from a gypsum mold, and create a wooden framework around the silicone mold.

 5. Mix gypsum to pour into the form work

 Fill a bowl half with water and add gypsum powder until the powder comes to the surface of the water.  Allow the gypsum to sit and slowly absorb the water.

 Mix thoroughly, removing any clumps but being careful not to mix in air.
6. Pour gypsum into form-work.

 7. Remove clay mold

8. Mix and pour gypsum into silicone mold.

 9. Carefully remove mold after cooling.