Every year for the holidays we like to make some ornaments for the tree. I really believe our tree should be a reflection of our family and not covered in store bought items. Those perfect trees? Those can stay at the mall. Instead I want our decorations to be perfectly imperfect, just like us! Plus, years from now, these handmade treasures are what I will hold dearest. Today we are blending amazing science with our Christmas decorating as we create Christmas ornaments from bioplastics using items in our pantry! An incredible Christmas STEAM project!
Make Plastic Ornaments with Kitchen Science
I’ve had some questions around the durability and longevity of these homemade bioplastics and in my experience they last years and years. In fact we have yet to have any degrade on us. It might be a fun experiment to see what breaks them down. My main tip would be to keep them dry and don’t drop them. I did break one of our milk plastic ornaments dropping it this year while decorating.
This past summer we decided to try our hand at a clear bioplastic. We tried a few recipes with no success, but then we tried gelatin plastic and it worked! We loved our little clear plastic creations.
So this Christmas we decided to make some clear gelatin plastic Christmas ornaments. And they look stunning with the Christmas lights reflecting through them!
BIO-PLASTIC CHRISTMAS ORNAMENT MAKING SUPPLIES
Gelatin packets (3)
Christmas silicone molds (we used Santa and Christmas trees, the same mold we used for our milk plastic ornaments and Christmas bath bombs)
Hot glue gun
HOW TO MAKE GELATIN PLASTIC CHRISTMAS ORNAMENTS
Add 75mL of water with 2 or 3 drops of food colouring mixed in and 3 gelatin packets to the pot. Whisk together over medium low heat until completely mixed.
Once it is completely mixed, stir very gently. The less you aggravate the mixture, the less foam will form. But you do need to stir to prevent hot spots and possible burning.
The mixture will start to steam and thicken a bit, when it does, remove it from the heat.
Using your spoon gently scrape the foamy layer off and discard. If you don’t remove all the foam now it will cause some cloudiness in your final plastic. This isn’t all bad and we left it on some batches and removed it on others. The better you are at removing the foam, the more clear your final plastic will be.
We decided to add a bit of glitter to our pieces. We did this by sprinkling the glitter inside our mold before pouring in the plastic mix. You can also gently stir some glitter into your mix while it is heating. The choice is yours.
Now carefully pour the mix into the molds. It will be hot, so be careful. If you notice a lot of bubbles, you can squirt the top with rubbing alcohol, just like we do when making soaps, to help remove bubbles.
Let the molds sit at least overnight before removing them from the molds. You will find they are quite rubbery at first but will harden over a few days into a nice hard plastic. During the hardening they will start to curl. I’ve tried so many things to limit the amount of curl. I find the best way is to leave them to harden in the molds for 4 or 5 days. Then another 2 days out of the mold to finish hardening.
In the interest of science, I recommend making a bunch and testing it to see what works best for you. I have a strong suspicion atmospheric conditions play a big role in how much curl occurs during the curing process. So your results may differ from mine. Plus, pulling them from the molds at various stages will give you some cool comparisons.
Once they are cured, you can add a piece of ribbon using a hot glue gun to finish your ornament and prepare it for hanging.
THE SCIENCE BEHIND GELATIN PLASTIC
This project, along with our milk plastic experiment, create what is known as bioplastics which are made from biomass or organic matter (think items in the kitchen!). Bioplastics are different from most mass produced plastics that are created from fossil fuels. There is a lot of interest lately in using bioplastics as a more environmentally friendly plastic creation method.
For these ornaments we used gelatin. Gelatin is created by breaking down collagen which is found in all animals where its function is to bind cells together. Collagen is a very long chain of amino acids, the building blocks of proteins, that bonds to itself in a triple helix pattern.
Gelatin has long chains of hundreds of amino acids. At room temperature it is solid, but when you heat it up the bonds between the chains loosen, allowing them to slide and stretch apart. Gelatin also has a strong affinity for water. Hydrogen atoms that are attached to the side of the chains can bond with water molecules. When we heat up and mix our solution we are weakening the chains, then during the cooling process those hydrogen atoms form connections with the water molecules. This is called a hydrogen bond.
In our solution we have added a LOT of gelatin to a fairly small amount of water. All those water molecules bond with the hydrogen molecules, then the amino acid chain also starts to bond with itself, trapping those water molecules within it’s complex 3D structure. If we used more water, we would end up with more of a gummy candy consistency or even a jello consistency. But in this experiment all the water molecules are used up, so once it finishes curing we end up with a very hard plastic. This bonding with itself and twisting of the helix pattern also explains why it tends to curl.
Fascinating, isn’t it? For even more information on chemistry of gelatin, check out this article.
And don’t forget we have a great resource on Chemistry for Kids.