How to make Galalith or plastic stone. A bioplastic from milk

This is an easy experiment, awesome for kids. Making it we will can explain our children what bioplastic are and introduce them into a chemistry world. Even in historical facts.

Galalith or Milkstone has an interesting history behind it. It was use to produce gemestone realistic imitations.

Other Galalith names: Milkstone, Erinoid (United Kingdom), aladdinite (USA), Casolith (Netherlands) and lactoloid (Japan).


  • 1 cup of milk
  • 4 small tablespoons of vinegar
  • food coloring (optional)

Recipe step by step:

You must to heat up the milk. It must to be hot but not boiling.

If you want different colors add the food coloring now.

Put the hot milk in a bowl or a cup.

Add the vinegar and stir it up 1 minute. You see how little casein flocculations are made.

You have it! Strain the milk with a strainer to separate the casein, shape it with or without molds and wait 2 days to dry.

I need to get these Coco Chanel gemstone.

First attempt making Galalith (without formaldehyde treatment)

how to make galalith with milk an vinegar, a science experiment

This is the first time I have tried to make Galalith. It is an experiment want to make for a long time since I heard of it. IIt is a good option to do with children on the weekend as the Fake Snow experiment.

It is easy to obtain the Galalith, the Casein, but not to mold and work with it.

This first attempt has been disappointing. I have obtained fragile and oily pieces

There is to make more experiments with features variations. I have made the recipe above. Hot (but not boiling milk) with food coloring and vinegar. When you add vinegar casein is formed instantly. Lumps and flocs are formed.

Strain this paste with a strainer. Better with a chinese cloth strainer.

Coloring food works well. The problem is to mold the mixture. I made two types of pieces. The first one pouring casein to a mold. The second one pouring and pressing it.

Pieces without pressure are brittle. Like this one.

However pieces molded with pressure are quite better. See below.

The best one has been this piece.

There is a rigid and light plastic. After a week he continues exuding “oil” but although it still gives a sense of fragility, something could be done from this quality.

A vinegar smell remain with this recipe. Maybe I used too much, because Galalith must to be odorless.

In next Milkstone experiments

Points to improve for next test are:

  • Improve water separation to obtain purest casein
  • Use lemon juice instead vinegar as in this Instructable
  • Treatment with formaldehyde to finish the piece and see what happens

Casein properties

Casein is insoluble in water and acid although contact with them or alkalis may cause crazing. It is odorless, biodegradable, non-allergenic, antistatic and virtually nonflammable (Burns slowly and brightly in air, but extinguishes with removal of flame source. Burns with odor of burnt hair.)


Buttons and gemmstones make with Galalith

Sources and references

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