Make your own plastic

Did you know that you can make your own plastic out of milk and vinegar??

For his 10th birthday, Aidan received the book Sneaky Uses for Everyday Things (affiliate link) from one of his friends. It’s a pretty awesome book. The book contains 42 different inventions to make out of household materials such as a homemade battery, an electronic greeting card, and a makeshift telescope. Aidan was really intrigued by the page on how to make plastic out of milk and vinegar. I stalled for several days on this one because it sounded messy and smelly, but we finally did the project and wow! It was easy to do and SO much fun!

To make plastic, you will need:

  • 1 cup of milk
  • 1 Tablespoon of vinegar
  • A small pan
  • A spoon
  • A strainer
  • Paper towels
  • Food coloring (optional)

First, put one cup of milk in a pan and heat it until warm. It doesn’t need to boil – just be warm.

Make your own plastic

When the milk is warm, stir in 1 T of vinegar. The vinegar will cause the milk to quickly separate into curds and whey. The acid in the vinegar causes the protein strands in the milk to coagulate. The curds are casein, which is used in the production of glue and some plastics. Who knew?

Make your own plastic out of milk and vinegar

Pour the contents of the pan into a strainer. Use a spoon to squish out the extra liquid.

Make your own plastic

Knead your plastic with your hands and use a paper towel to dry off any excess moisture.

Make your own plastic

Then mold your plastic into whatever shape you want! It’s a little tricky to mold because it has a texture sort of like ricotta cheese (which is probably what it is?). We flattened it out and used a measuring spoon to cut out circle shapes for key chains.

Make your own plastic

We also made a second batch and added a few drops of blue food coloring to the milk before heating.

Make your own plastic

Let your creations dry for 48 hours or more. I had my doubts about this stuff becoming anything that resembled plastic, but it worked!!! We found that smaller, thinner shapes dried better and faster. The blue color dried darker than it looked when it was wet.

Make your own plastic

We used straws to make holes for the key chains before they dried. Our holes shrank as they dried, so beware! They were barely big enough to be key chains once they dried.

You can paint your plastic to decorate it however you want. We used acrylic paint.

Make your own plastic

What else can you do with homemade plastic?

  • Use cookie cutters to cut out shapes
  • Make magnets for the refrigerator
  • Make playing pieces for a board game

For more crazy science fun, check out our exploding chain reaction made with craft sticks!

28 Comments

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  1. Carrie Aug 20, 2013

    What a neat activity!! I am pinning it so we can try it when my little one is a bit older.

    Reply
  2. Heidi Aug 20, 2013

    We are definitely going to try this one! Looks like it worked out great!

    Reply
  3. Kimberly Aug 20, 2013

    This looks so neat! Thank you for posting it!

    What kind of milk did you use (whole, skim, etc.)? Do you think it would make a difference?

    Reply
    1. Sarah Aug 20, 2013

      We used 2%. I'm not sure if it matters or not - that would make a great experiment right there!

      Reply
  4. Trisha @ Inspiration Laboratories Aug 20, 2013

    Making plastic is actually on my science project to-do list. The recipe I found uses starch, glycerine, and vinegar. Milk and vinegar sounds much easier! Does it smell like cheese? I wonder how long it will take to break down. I think most biodegradable plastics stick around for a while, but I'm not sure how long.

    Reply
    1. Sarah Aug 21, 2013

      It does not smell like cheese, thankfully! It smelled like vinegar, but dried with very little smell. Not sure how long it will last - I guess we'll find out!

      Reply
      1. Leanne M Jan 21, 2020

        Did this go moldy?

        Reply
        1. Sarah Jan 29, 2020

          No, it does not get moldy. We didn't keep it forever, but it lasted several months!

          Reply
    2. Someone Feb 20, 2018

      I don't know how long it lasts, but it does not smell like anything, considering it's made out of vinegar and milk!

      Reply
  5. Tori Aug 21, 2013

    This is exactly how you make what is called farmers cheese (minus a couple steps). It's very much like ricotta, but not as dry. I never would have thought you could make cheese with it. We will have to try this.

    Reply
    1. carol Feb 2, 2016

      Which of course is scary since I want to make both farmers cheese and this plastic.

      Reply
  6. Tori Aug 21, 2013

    *plastic, not cheese. Oops. Lol

    Reply
  7. Robbin Aug 22, 2013

    Bet this would make some very neat Christmas ornament.

    Reply
  8. JoAnna Richards Craig Aug 23, 2013

    love This:-)

    Reply
  9. sara Mar 25, 2014

    really cool

    Reply
  10. ashley Jun 1, 2014

    do you think i can use a microwave to warm the milk?

    Reply
    1. Renae Jun 19, 2014

      Yep! I just experimented with it in the microwave and it worked great! I did discover that you have to have it molded before it gets very cool or it just crumbles. Don't think you could reheat it, either.

      Reply
      1. carol Feb 2, 2016

        From what I've read other p[laces you cannot reheat it.

        Reply
  11. Ashley Jun 8, 2014

    What did you put it on to dry?

    Reply
    1. Sarah Jun 8, 2014

      We put it on a paper towel at first, and then just put it on the window sill.

      Reply
  12. Leighanne Jul 24, 2014

    We used 1% Milk and couldn't get the milk to curd :-(

    Reply
    1. Leighanne Jul 24, 2014

      Tried again, this time using the microwave and WHITE vinegar. MUCH better! I wonder if a higher fat milk would produce better results as our "cheese" didn't stick together too well...

      Reply
      1. Sarah Jul 24, 2014

        We used 2%. I wouldn't think it would be that different from 1%, but maybe it is. Now I'm curious to try whole milk!

        Reply
  13. Kelly Harris Jul 25, 2014

    I just have to say that I am new to having kids at home full-time (they previously went to daycare and I recently hired a nanny full-tim) and I LOVE your website! I struggle with creativity and you have the greatest ideas and ways to make home fun that won't break the bank!

    AWESOME!!

    Reply
  14. Meagan Oct 25, 2014

    I will have to try this with the kids. I pinned it and I would love to have you link up at the Geeky Educational Link Up: http://www.morethanacouponqueen.com/search/label/Geeky%20Educational%20Link%20Up

    Reply
  15. Lorna Nov 18, 2014

    Did it not smell? We'll be trying this today in Malaysia, so I'm a little bit worried that the hot climate here might not work well for the drying out process, but I'll let you know!

    Reply
  16. Mary Dec 8, 2014

    We just tried this with skim milk - it worked, but I think milk with fat will work better. We're going to get some 2% and some whole milk and try different experiments. The skim milk made very little "plastic." Will see how it goes once it dries. Thanks so much for this idea!

    Reply
  17. Keerthi Mar 20, 2015

    Cool!

    Reply
  18. Greta MacCallum Apr 12, 2015

    I love this idea. My boys are toddlers so I am pinning this for when they are older.

    Reply
  19. Mattie Jun 8, 2015

    This appears to be more like dried out acid-set cheese as opposed to a more polymer style plastic. This is essentially how one makes paneer-- an Indian cheese that has a the neat culinary property of not melting when heated during cooking.

    Reply
    1. Sarah Jun 9, 2015

      Yes. But, plastics made from casein (the protein in milk) are actually used in manufacturing! This article has some interesting information. Apparently, casein plastic is useful in making buttons because it can handle the heat of the dryer.

      http://www.plastiquarian.com/index.php?id=60

      Reply
  20. Elena Jun 8, 2015

    Im currently an activity assistant at a nursing home. I surely can incorporate these ideas with my residents and have lots of fun and laughs. It will also help out our residents with motor skills and so forth !!! :-)

    Reply
    1. Sarah Jun 9, 2015

      That's great!!

      Reply
  21. Toni Jun 9, 2015

    After the milk separates it isn't ricotta cheese it is actually an Indian cheese called Paneer. You strain it over night and then cut it into squares and fry it slightly. You can eat it that way but it is added to different Indian foods. :)

    Reply
  22. Marie Jun 24, 2015

    Neat! Hope it's ok I pin it? Have to try this with my kid!

    Reply
  23. mhairi crolla Feb 18, 2016

    wow this is brilliant. just about to do on my sleepover with my brownies and was trying out it.

    love it

    Reply
  24. Elliott Jul 27, 2017

    This is interesting and I will try it soon,I am needing a cheap mouldsble substance for a project that I have,which is to make a insert tray for a socket set,inside a toolbox... I do recall reading anecdotal story about making plastic this esy in the 1950s,before they switched to oil bases..apparently sour full cream.milk was used...recycling milk that would otherwise have been wasted..don't know about the life of the resjlting product,or if any other additives were used..

    Reply
    1. Interested Nov 6, 2017

      By the way would anyone know if the type of vinegar has any effect on the plastic? I read in several sites (youtube included) that white vinegar is a necessary addition. However I am not so sure and because I only have Balsamic vinegar, Apple cider vinegar and Japanese rice vinegar (tastes nice) I am scouring the web for results. Any thoughts on this? Is white necessary? Or can other vinegars be used? Also the last time I made this (no, I have no idea how I did it) the plastic came out very greasy. After several attempts I established that it must have something to do with the fat. So I reduced the fat. The plastic failed. Is there any way of preventing or minimising this grease? Maybe a cover of some sort like a plastic film? Well, thanks for reading this far down and please consider sharing your thoughts on this! Any help is welcome!

      Reply
  25. Amie Dec 20, 2017

    The end results makes me think of salt dough ornaments. It has a similar look.

    Reply
  26. Josula Sep 22, 2018

    This is how paneer cheese is made. Really tasty in Indian food.

    Reply
  27. Sapphire Mar 13, 2019

    It is necessary to boil the milk?

    Reply
  28. Jess Feb 10, 2021

    Very cool!

    Reply

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