MIXING RATIO: 100:42
VCat Setting Time: 6-25 Minutes
Which translates as 100g plaster 42g water. Since 100cc or ml of water = 100g, one can assume 100g plaster to 42cc water. Other ratios are on the technical data sheet, click the appropriate tab to view.
To approximate the requirement for the mould, fill the mould with water and empty into a mixing container, ideally graduated. Divide the total volume by 42 and multiply by one hundred for the correct weight of plaster. Sprinkle or seive the plaster into the water and allow to abosorb water fully before stirring
Do not whisk, you will entrain air and cause bubbles!
You can also estimate the amount of plaster needed by sprinkling plaster onto the measured water and continue to do so until the plaster level reaches the water level in the container. You will see a sub surface "lunar landscape" like picture. Our friends at hirstarts.com also have a pictorial mixing guide for this Heath Robinson method.