PlasterMix
Plaster batch calculator & pour timer

The next batch for the mould on your bench.

Enter a mould's volume, choose a recipe, and set a safety margin. PlasterMix calculates the water and powder you need in grams or ounces, along with the working time and demould window.

Coming soon to the App Store

How it works
The PlasterMix icon: a navy bowl with an ochre rim, filled with cream plaster, and a single drop falling into it.
How it works

From mould volume to a cast that's ready to check.

  1. Calculate

    Enter a mould's volume, choose a recipe, and set a safety margin. PlasterMix calculates the water and powder you need in grams or ounces, along with the working time and demould window.

  2. Time

    Start the timer and follow the slake, stir, and pour phases.

    • Slake
    • Stir
    • Pour
    • Demould window

  3. Pour and check

    A soft chime and local notifications mark each phase, including when the cast is ready to check.

Calculator
Volume900 mlmould
Margin+10%safety
RecipeYour recipebuilt-in or custom
Water— gor oz
Plaster— gdry mix
Illustration in the app's style, not a screenshot. PlasterMix calculates the figures for your recipe.
PlasterMix Pours screen: a studio journal with stat cards for batches, plaster used and material costs, filter chips, and a saved pour of Plaster of Paris for a 900 ml mould.
Screenshot of the Pours screen in PlasterMix.
Studio journal

Review past pours and repeat a batch.

Your pours, moulds, and recipes live in one studio library, synced through your private iCloud.

  • Save moulds and combine multiple moulds into one pour.
  • Create custom recipes, mark favourites, and set a powder price to estimate material costs in your chosen currency.
  • Switch between metric and US measurements.
Features

Plan your pour

  • Calculate water and powder from mould volume.
  • Add a safety margin from 5% to 20%, or turn it off.
  • Time slake, stir, pour, and the demould window.
  • Save moulds and combine multiple moulds into one pour.
  • Create custom recipes, mark favourites, and set a powder price to estimate material costs in your chosen currency.
  • Review past pours and repeat a batch.
  • Switch between metric and US measurements.
  • Sync your studio library through private iCloud.
Privacy

Your studio, your data

Pours, moulds, recipes, and settings stay in your private iCloud database and sync to other devices using the same Apple ID.

Read the privacy policy

  • No account to create.
  • No ads.
  • No trackers.
Before you mix

A note on ratios and setting times

Built-in ratios are based on published workshop consistencies and are intended as a starting point. Read the bag, weigh your batch, and use your own judgement. Setting time varies with temperature, water, and mixing technique.

PlasterMix is a studio tool and is not affiliated with any plaster manufacturer.