calculate VOLUME using cottle boards and a cube-shaped object
Measure length, width, and height of your mold and your object.
Use the equation V=LxWxH to calculate for each of the volumes.
Subtract the volume of the object from the volume of the mold.
Input this number into the Volume section of the Plaster Calculator.
Use the first option (Keith Simpson) to measure your plaster and water.
example of how to calculate the weight of plaster and water
calculate VOLUME using Flashing or clay and a cylindrical object
Measure the height and radius of the mold and the object
Use the equation V=πr²h, or input your measurements into the Plaster Calculator, to find the volume of your mold and object.
Subtract the volume of the object from the volume of the mold.
Input this number into the Volume section of the Plaster Calculator.
Use the first option (Keith Simpson) to measure your plaster and water.
example of how
to calculate For
THE volume of a mold
Example of how to use
the plaster calculator
to calculate the weight
of plaster and water
plaster mixing Steps
Make sure you have double-checked your plaster and water calculation and mold preparation- Don’t forget the release!
Draw a fill-to line inside of the mold 1-2 inches above your object
If you are pouring the second half of a two-part mold, remember to make keys (notches).
Sift the plaster into the water within 1 minute
Let the plaster slake (fully hydrate) for 2 minutes
Mix for 2 minutes- OR until the consistency thickens to heavy cream and you can see a line on the surface if you draw with your finger
Pour: Use your hand to direct the pour down the inside of the cottle boards to prevent splashing
Lightly agitate the mold to bring bubbles to the top
Wait- the plaster will heat up then cool. Once it is completely cool, it is ready to de-mold
Put your mold on our metal rack to dry. It will take a few days to a week to completely dry before you can use it