Remix PPE into other PPE

I have been wanting to remix some of the many amazing projects people have come up with to fight Covid-19, and wanted to find a way to make use of existing materials that would otherwise be discarded. After some experimentation, I found out that some garbage PPE already can serve as raw material for new PPE! There are many ear-saver designs but most of 3D printed or laser cut from brand new material. For this project I remixed one of the designs from the NIH https://3dprint.nih.gov/discover/3dpx-013777 and just made it a little more durable with the face design for using Polypropylene.

For those who just want to get to the meat of this How-to, here's the basic recipe:

1. Slice up a mask and keep the two outside layers (throw away the middle)
2. Heat the layers between parchment paper at 200C/400f
3. Fold and Reheat the Plastic to desired thickness
4. Laser cut your design into the plastic sheet
5. Enjoy!

The supplies you need are pretty simple, and my hope is anyone can do this at home!

Materials

• Old, discarded masks
  • Let sit for 2 weeks, or dunk in alcohol because they might be gross
• Laser Cutting Files (Samples attached)

Tools

• Heat Source
  • I used an electric skillet
  • You could also use an oven or toaster oven

Most of the standard, blue masks you see have three layers. The pictures above show examples of melting down each of the three layers and how they come out.

The two external layers are made from what they call "Melt Blown Polypropylene." This means in a factory somewhere, they have a bunch of polypropylene they heat up, and squeeze through a whole bunch of tiny holes while blowing air at them. This creates this nice random, static-y, fluffy material with VERY SMALL HOLES that is good at stopping particles and liquids.

External Layers The mask factory takes sheets of this fluffy polypropylene and slice them up to make the two exterior layers of your normal blue mask. These layers are hydrophobic and the main goal seems to be to keep your fluids in with you, and keep others fluids out. A cool thing about polyproylene is that it is a THERMOPLASTIC. This means you can melt it, put it in a shape, re-melt, and re-shape, (almost) as much as you want! This is how things like 3D printing work! It's also how plastic recycling in general works (Like all the great projects with the fine folks at https://preciousplastic.com/ ): you chop up certain types of plastic, melt it down, and re-use to make other projects.

Inside Layer (Problem Material!)

The center sheet is some kind of other material. It's hydrophillic and made to absorb moisture. The concept seems to be that any wet stuff that makes it through the outer layers gets absorbed in this layer. This is also why this layer tends to get mold and gross if you keep re-using the mask. This center layer is also the one that gives us some problems. We can't just melt down all three layers of the mask together, or we end up with a weak, brittle plastic.

Chop out the middle part of the mask that isn't fused together. You should now have 3 layers that easily come apart. The middle layer is the troublesome layer! get rid of it!

Collect the outside layers together. As far as I can tell, the only difference between the two external layers is that the one is dyed blue. So you can mix them together if you want!

I realized WHY they make them blue though, because the white colored layer gets easily discolored and gross looking. So mixing might be a good idea overall!

Put parchment paper around your plastic so it doesn't stick to anything and make a huge mess

Put something heavy on top of your plastic parchment paper sandwich and let it melt. It should be all melted well in about 5 minutes.

Wikipedia says Polypropylene melts at 130 to 171 °C (266 to 340 °F; 403 to 444 K), and I actually set my skillet a little bit lower than 200C (like 175C) after it has heated up for a while. If you are using an oven, I would aim for a lower temperature as you will get more smooth heating overall. The Electric skillet method tends to need a bit higher heat because the top surface isn't heated.

Take your plastic sandwich away from the heat, and let it cool. You will likely need to keep the weights on it to stop it from curling up as it cools.

If Needed: Fold and Re-Melt to Desired Thickness

Chances are your first melting might come out too thin (especially if you don't have many masks). No problem! Just fold the plastic into about the thickness you need, and re-melt it together.

The reason we made big flat sheets is because then it is super easy to use them with a laser cutter!

Polypropylene is not many people's first choice for laser cutting, but it's not too terrible to cut. It tends to have meltier edges than something nice like acrylic, but if you cut it with quick movements, it should be fine. These won't be good for making super refined parts that need high precision tolerances (like intricate gears), but should be fine for more laser cutting purposes! Don't make your sheets super duper thick, or they will be a bit more tough to cut through with most regular laser cutters.

Load your sheet in, load up the design, and cut out your design!

I remixed a design from the NIH, my remix is posted above in the materials section.

https://3dprint.nih.gov/discover/3dpx-013777

from a sheet made from about 14 garbage masks, I made 2 ear savers, but probably could have gotten at least 3, if i tessalated 3 designs together. If you make a big sheet you can make a bunch of these things!

*notice how the pure white ones turn out gross looking? I think it's because of the wood and parchment paper getting scorched a bit

Lots of disposable plastics are made with polypropylene which means you can combine them! Peanut butter lids, some yogurt containers, and more are made from Polypropylene. Just look for the "5" or "PP" plastic recycling symbol.

*** NOTE PLEASE DONT GO MELT PLASTIC THAT YOU DON"T KNOW WHAT IT IS!

PP itself shouldn't off-gas bad fumes, but some people say that there might be additives or inks that might make bad smells, so always do this in a well ventilated area!

Just lay down a bunch of PP lids on your parchment paper, and then use your salvaged face mask materials on top. They are great at filling in the gaps between circles! Melt and cut just like instructed before!

Now you have nice, even, homogeneous, blank sheets of Polypropylene. There's all sort of things you can do with this! You could melt them down and squeeze them into thicker blocks or bricks to do things like using a lathe to make pens or chess pieces (like these folks have a nice video showing how to do this with HDPE (another thermoplastic)