LHM Silicone Face Mask

This instructable presents all the steps for making a silicone mask using 3d printed parts that can be downloaded from: https://www.thingiverse.com/thing:4288286 and 2 parts component silicone rubber.

First of all: this mask is a prototype and has not been tested or approved by any field specialist, so use it at your own risk

Second: i made the mask as a proof of concept and didn’t work on the fine details like sanding the printed parts that would make the mask look way better and without any flaws that you might observe in the video or photos. Also the silicone rubber i used is not designed or recommended by the producer as a skin friendly material, and even though i had no problems wearing the mask, i would recommend choosing a skin safe silicone material like the dragon skin silicone rubber.

I am still improving the mask so feel free to comment if you encounter any problems or have new ideas on how to make this mask better. Together we can make this better.

I made another instructable with the hepa filter for the mask that you can check out here:

https://www.instructables.com/id/DIY-Universal-HEP...

I designed the mask based on these rules:

1. Simple production process that can be implemented in all makers communities around the world;

2. Short production time - 2-3h / mask for each mold - if i would use 10 molds, i could make 10 masks every 3 hours wile 3d printed masks take about 4-5h / mask for each printer;

3. Repeatability of the process - one mold can be used for as many masks as you please with the same results;

4. Mask should be reusable - silicone can be sterilized and reused, and the filter also can be sterilized with uv lights and used for 3 to 6 months before changing it

5. Mask should be easy to disassemble for individual sterilization of each material;

6. Mask should fit tightly, make a good seal on various face configurations - silicone rubber has this quality;

7. Filter should offer protection equal or better than n95 masks - the tight seal and a h13 HEPA filter should provide 99.97%efficiency in air filtration;

8. Easy to put on and take off - unlike the n95 masks that need proper fitting, this mask takes the shape of the wearer’s face on it’s own;

9. The wearer should breathe easily - the breathing hole it’s 36mm in diameter witch should provide enough air circulation;

10. Mask should be comfortable - the silicone rubber is soft;

The process it’s pretty easy and made as simple as possible by skipping a few steps like preparing the mold properly, using demolding agent, using a vacuum machine to take out the air bubbles from the liquid silicone. I intentionally simplified the process just to prove that it can be done with minimal equipment and skills but I would encourage at least a proper refining of the mold for way better results.

Basically, you mix 2 equal parts of liquid silicone, pour them into a mold and wait for a few hours or less depending on the type of silicone. Boom! Mask ready ;)))).

1. 3D Printer

2. Bicomponent Silicone Rubber

3. Tools: jar, mixing spatula, sandpaper, spatula, screwdriver.

4. Materials: PLA, adhesive tape, sculpting was or some sort of putty for sealing the mold, M4 bolts and nuts

First I 3d printed the parts necessary for making the mold.

The parts are designed in such a way that they don’t need support, therefore not much post processing to be done . Because of this reason I separately printed a ring that has to be glued to the interior part of the mold. Also the two halves of the exterior parts have to be manually rectified for a better fit.

I used M4 nuts and bolts for assembling the two halves of the exterior shell. This assembly makes it easier to get the part out after it hardens. There is not enough space to use the washers in the assembly so I left them out.

I used adhesive tape for the gap where the clips for the elastic band go. Another way to do this would be to skip this step and cut the holes manually after the silicone cures. I haven't tried it so I don’t know what could go wrong, but it could be a way to simplify things, or complicate them.

Next, I used sculpting wax to seal the mold.

The silicone has a high fluidity and if the mold is not properly sealed it will make a big mess.

Instead of sculpting wax, plasticine or various types of clay can be used as long as they won’t harden over time. The third and fourth part of the mold, colored with blue in the 3d sketch are like a bolt and a nut.

I will screw the nut and close the mold in the middle of the pouring process to ensure there is no air trapped inside the mold.

The silicone I used is za22 made by Zhermack, a two component high fluidity liquid that sets in 60 min - 90 min and has no heat transfer in the hardening process witch is great because this means that the 3d printed mold does not endure any stress in that period and I can make as many masks as I want with only one mold.

I recommend doing your own research before buying the right silicone rubber for the job.

Links for various silicone rubbers:
What I used: https://www.zhermack.com/en/product_category/indu...

Data sheet: https://www.zhermack.com/en/product_category/indu...

Dragon skin: https://www.zhermack.com/en/product_category/indu...

The base and the catalyst are mixed together in equal shares. while mixing, it is important to check that no unmixed component remains on the base or the sides of the container.

Vacuum degassing is recommended to minimize the air bubbles in the cured object.
Skipping this part, I try to take out as many air bubbles as I can by rotating the jar at an angle, blowing out the bubble and pouring the silicone in the mold from a high point and in a thin string.

Just before the silicone starts spilling out of from the unclosed lower part of the mold, I close it with the threaded cap and continue pouring until the mold is full.

After 90 minutes I opened up the mold.

The silicone rubber does not stick to the printed parts even without using demolding agent. If another type of silicon is used, I would recommend testing it first on a printed part before use, to prevent ruining the mold.

I used a spatula to separate the two parts of the exterior shell.

It was a bit tricky with the threaded cap. This piece will be redesigned in the future to be unscrewed with a large screwdriver.

I use scissors to take out any excess material.

The LHM Silicone Face Mask is ready to be used right after you add the elastic band using the two 3D printed clips (red in the 3D sketch).

Don't forget the HEPA filter.

Instructable here: https://www.instructables.com/id/DIY-Universal-HEP...

Stay safe! Stay home!