Make Plastic From Milk Activity
milk plastic ornaments decorated with glitter on a plate. Great for simple science experiments and fun projects for kids.

Making DIY milk plastic 

If you’re like me, you’ll be often on the lookout for science experiments for kids to do at home, STEM activities, crafts for kids and especially cool experiments to do at home with household items!

That’s why I love that you can turn milk into plastic easily at home – and kids love it!

Can you turn milk into plastic? Really?


Ok, well it’s not exactly like the kind of plastics we see around us every day, but it is a seriously cool STEM activity.

Children will get to see the weird, super-fast effect that vinegar has on milk, enjoy some fun science and get crafty making plastic creations.

I’ll show you how to make an at-home version of casein plastic, which was actually used sometimes about a hundred years ago to make things like buttons, beads and pens.

It’s ideal if you’re looking for easy science projects for kids to do at home, and great for the whole family, because even toddlers and preschoolers can join in the fun.


Follow my simple and quick steps for this making milk into plastic craft, and don’t forget to tag us @supastem and use the hashtag #supastemclub so we can see your kids’ amazing creations!

Two plastic milk DIY crafts on a white background. It shows what basic and interesting designs you can mold

Here’s what ingredients, materials and equipment you’ll need for making plastic out of milk:

Full-fat milk, white vinegar, large mug, paper towels, spoon, microwave and microwave-safe container or stove and pan.

Optional: glitter, cookie cutters, paint or markers, food colouring.


How to make your own plastic:
1. Take 1 cup of milk and heat it until it is hot, but don’t let it boil. It should be steaming. You can heat it in a pan on the stove, but using a microwave is quicker.
Any bowls, cups, small jugs or other microwave-safe containers will work.

2. Add 4 teaspoons of the vinegar to a mug and then carefully add in the hot milk. Now you’re going to see some cool science at home!

3. Stir the mixture slowly for no more than a minute. You’ll notice the mixture has gone lumpy. These are curds.

4. Now layer 5 paper towels on top of each other. Use the spoon to remove the curds from the mug and put them on the paper towels.

You can tilt the spoon and press the curds against the side of the mug before you take them out to squeeze out more of the liquid.

5. Once you’ve collected as many curds as you can, press down on them with more paper towels to absorb more of the liquid.

You only want to absorb enough for it to have a dough consistency. If you soak up too much it will get crumbly and hard to mould. That’s what happened to our milk plastic the first time we tried this experiment!

6. Now mould the curds into a ball. Knead the ball to create a putty or dough.
You can now shape your milk plastic using cookie cutters or by hand.

Add glitter or food colouring if you like. There are lots of different ways you can decorate your designs.

If you want to make beads, you can make balls of dough and push them onto a kebab skewer to dry.

7. Leave your creation to dry on a clean kitchen towel for at least two days. They will shrink a little bit as they dry. Once dry, you can decorate it further if you like using paint or markers.

Now you’ve learned how to make plastic with milk! Don’t forget to show us your designs using @supastem and #supastemclub!

Questions for kids

Here are some questions to get your kids talking and thinking about this plastic milk experiment!

What do you think happens to the milk when you add vinegar? Why? What do you think would happen if you put your plastic made from milk in water? What do you think are the disadvantages of making plastic from milk? What are the advantages?

The science 

How does it work? Let’s take a look at the chemistry and STEM learning opportunity in this fun plastic milk science project.

Milk contains a protein called casein, which dissolves in water. When vinegar is added to it the milk curdles and lumps appear.

This is because vinegar is acidic and adding something acidic to the milk stops the casein from being able to dissolve in the water anymore.

You are then left with a mixture of solids (curds) and liquids (whey). You can mould the curds into shapes like beads, ornaments, jewelry, toys – or even more tricky engineering challenges – and once they’re dry they will stay in that shape. This makes milk-based plastic.

Your homemade milk protein plastic isn’t exactly plastic like the kinds we see around us nowadays, but it has some similar properties.

The process you used to make the milk plastic is actually very similar to that used by many people around the world to make a kind of edible cheese. Technically you’ve made edible plastic, but I wouldn’t recommend it!

For more fun and easy science experiments for kids at home and other kids’ activities ideas, join our club and get our popular children’s activities eBook for free!

You can get alternative instructions for this milk plastic activity from WikiHow.

Thanks to Science Bob and Steam Powered Family for inspiring us to make our own plastic from milk!


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