How to use this calculator?

• Select a base shape. The related input fields will appear automatically.
• Enter the dimensions of the shape, or input the volume for a free form.
• Select the intended use: mold, panel, or stamp.
• Enter casting loss (%) if applicable — default is 0%.
• Click Calculate to view the required water and gypsum quantities.

Improving fluidity without changing the ratio

If you don’t want to change the plaster-to-water ratio, but still want a thinner, better-flowing mix for fine details, you can adjust handling techniques and additives. Here are some smart ways to do that:

How to improve fluidity without altering the ratio

• Dish soap (1–2 drops): Reduces surface tension → plaster flows better and bubbles dissipate more easily.
• Use lukewarm water: Warm water speeds up the reaction, but lukewarm water makes the mix more fluid without changing the ratio.
• Let it rest before stirring: Allow the plaster to soak 15–30 seconds in the water → better hydration and smoother mix.
• Stir slowly and evenly: Prevents lumps and air pockets → smoother results without adding extra water.
• Use a mechanical mixer on low speed: Ensures a homogeneous mix with better flow and minimal air incorporation.

Why does this work?
The ratio defines the chemical reaction and strength of the plaster. But the workability can be enhanced with physical techniques and surface-active agents like dish soap. That way you retain strength while achieving finer details.