*1- How to calculate the volume of plaster mix you need*
Find the container’s volume:
• For a cylinder: Volume = π × r² × h
• For a cube/box: Volume = side³ (or length × width × height)
Then, subtract the piece’s volume:
• Container volume − Piece volume = Mix volume
*2- Simplified formula (the one I recommend)*
Plaster (grams)= Volume × 0.885
Water (grams/ml)= Volume × 0.615
Example for 1000 cm3:
Plaster= 1000 cm3 × 0.885
Water= 1000 cm3 × 0.615
*3- Another way:*
Volume × 1.5 = Mix required (grams)
Then split into plaster and water:
• Plaster (grams)= Mix × 0.59 (59%)
• Water (grams/ml)= Mix × 0.41 (41%)
Example for 1000 cm3:
1000 cm3 × 1.5= 1500 grams
Plaster= 1500 × 0.59
Water= 1500 × 0.41
*4- (for those who want to do the maths!)*
Water to plaster ratio: 70 ml of water for every 100 grams of plaster (41%/59%)
Density of plaster powder: 2.3 g/cm³
Density of set plaster block (using this ratio): 1.5 g/cm³
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Music:
Imagination - Artist: Ryan
Track: Off She Goes
Music composed and recorded by Oak Studios
Creative Commons - Attribution ND 4.0