Recycle Styrofoam Into Hard Plastic Jewelry

I'd like to begin my first Instructable with a little grade school science lesson.

Styrofoam is the trade name for expanded polystyrene. "Expanded" means that it's filled with air to make it lightweight, which makes it very hard to clean and therefore very hard to recycle. There are a lot of places where you can't recycle Styrofoam locally at all. If you throw it away, it ends up in a landfill with an estimated decomposition time of 500 years. It will outlive you, your children, your grandchildren, your great-grandchildren...

I've always wanted to repurpose plastic and cast it into something new, but melting plastic is extremely toxic and I don't have a space with proper ventilation and other safety measures to do my work in. The point is, I wanted a safe way to upcycle Styrofoam into something useful without creating a safety hazard.

Styrofoam can be dissolved by using an organic solvent. This isn't melting, as you don't change the temperature. This also isn't a chemical change (i.e. something that could produce another substance as a result.) It's a physical change, similar to dissolving table salt in water. Styrofoam is essentially granular, like salt, and dissolves in organic solvents (e.g. acetone) like salt dissolves in water. The resulting plastic goo can be cast in a mold, and dries into hard polystyrene! (Learn more about this process here.)

Acetone is sold as both nail polish remover and paint thinner. It's safe when compared to substances such as hot melted plastic, though I encourage you to read the MSDS of any craft material you use and ventilate your working area well. (Fun fact: acetone can actually be produced by the human body!)

Some notes on materials:

• Your mixing container and stirring implement must be made of materials that don't react with acetone. Silicone, metal/steel, wood, ceramic, and glass are all safe to my knowledge.
• Your mold must be silicone, not plastic. Silicone molds are very easy to work with and you can even make your own! For this project, I have had the best luck with simple shapes without many sharp corners. If your shape is too small/thin in any place, it might break. The mold I use here is 26x29mm. (I purchased my mold here!)
• Acetone is highly flammable. Don't use the tools from this project for anything food-related and don't expose them to heat!

• Disclaimer: No crafting process can be 100% perfectly eco-friendly -- I still use acrylic paints here, and though they are made of plastic, this project reduces waste instead of producing waste so I consider it a win. You can also try other paints that don't use synthetic binders! I haven't personally had the chance to do so yet, so I'd be excited to see the results if anybody tries it.

Casting:

• Expanded Polystyrene / Styrofoam
• 100% acetone
• Container for mixing
• Stirring tool
• Silicone mold of your choosing

Decorating:

• Assorted sandpaper
• Chalk paint, especially if your mold has a shiny surface
• Paintbrush
• Cyanoacrylic glue, or any glue with similar bonding properties
• Jewelry findings, I've used glue-on necklace bails and tie tack pin backings
• Any other paints, finishes, embellishments, etc. of your choosing!

The exact amount doesn't matter as long as you have enough to cover the bottom of the container and submerge small pieces, because the Styrofoam doesn't need to absorb all of the acetone, just enough to lose its shape. I usually use 1-2 tablespoons.

The Styrofoam will fizzle and dissolve into a plastic goo. Note that most of its original volume was actually air. The fizzling is this air being released. With the air gone, the resulting polystyrene is much denser and the volume decreases substantially, meaning that the volume of Styrofoam you need in the beginning will be greater than the volume of your mold.

Keep going until you have enough plastic goo to fill your mold. Stir frequently to collect it into one mass. I recommend working quickly because it gets harder to work with when it starts to dry!

Scoop the substance out of your container and smooth it into the mold, being careful to fill every part.

Please note that the back of your piece that's exposed to air won't be perfectly smooth! You may notice some air bubbles forming as the acetone evaporates. I pop those with a sewing needle or toothpick.

I get the best results when I flip the piece in the mold as soon as it's hard enough to remove without distorting it. This depends on the size, at least 12 hours in my experience. I usually wait around 48 hours for the piece to dry in its entirety before unmolding and decorating it.

And bask in the glory of both creating something cool and saving plastic from a landfill!

I used various grits on a sanding sponge to smooth the blemishes out. Some molds, like mine, create pieces that are shiny, so it's important to sand those a bit so your paint will stick.

I specify chalk paint because, in my experience, chalk paint will stick to anything, and anything will stick to it, so it makes an excellent primer for plastics that might otherwise not take paint well.

I usually do two coats to cover up any little divots on the surface of the piece!

You can do anything you want here! For my pieces, I painted a color coat with acrylic enamels or multi-surface acrylic paints and added spots with the white chalk paint. I also added a layer of glow-in-the-dark paint, but that doesn't show up well on camera! I sealed the pieces with Mod Podge Dimensional Magic. (For a more durable finish, I'd recommend using a clear enamel, but I didn't have any when I made this.)

I've only used glue-on findings so far in these projects. Pictured here is a glue-on necklace bail!

Thank you so much for reading! ヾ( °▽°)ﾉ*:･✧

I'm very excited to make more of these and hope to re-open my Etsy shop and stock it with recycled pieces soon.

I hope that you enjoyed this tutorial and that it helps you make something wonderful! Please let me know if you have any questions!