The goal of this article is to show you how to create a mask that is effective against respiratory viruses using materials found in most households. No mask is 100%, as seen by the study in part 1 comparing N95 to surgical masks. It is relatively effective only. My other criteria are that, not only must it meet some known standard of protection, but must also be reusable, washable and comfortable enough that you could wear for hours if you had to.
Logic tells me that with universal precautions, where everyone is wearing some sort of mask and with the addition of proper hand hygiene, it would really help stem this Covid19 pandemic. We need to assume EVERYONE has a Covid19 infection because asymptomatic carriers can still spread the infection. This is called presymptomatic transmission. We need everyone to wear a mask.
Let’s go step by step as to how to make an Effective Reusable Face Mask.
What fabric to use?
For fabric, I recommend using 100% cotton. Cotton is highly absorbable, so things tend to stick to it (but not water resistance). Also cotton is washable in hot water and high heat of dryer and comfortable against your skin. I chose to use the color white because it allows for the option to use bleach in the wash (more about this in part 3).
Thicker bed sheets and pillow cases with high thread count and are other options for fabric. I bought 100% white cotton fabric from Joann Fabrics. The fabric was probably too thin to use as a single layer. I hoped the weave would tighten after I pre-washed it in hot water and high heat of dryer. It did, but not enough. With 100% cotton, you should pre-shrink the fabric before sewing with it. If you don’t, your finished product, in this case your mask, will shrink after it’s first hot water or high heat dryer exposure. I decided that with my current fabric, to use it as a double layer so that it was thick enough that I could not see through it. In your finished product, when you hold it up to the light, you should not be able to see through it. If you can see through it, it is not a good filter.
As you will see later, with the mask pattern that I used, I ended up with a mask that was 4 layers thick with a pocket. The pocket allows for the option to put additional protective filter(s). I made a 15 x 15 inch cardboard template to guide cutting out the fabric pieces. The fabric was folded in half and ironed to remove the wrinkles and flatten the fold. Final fabric piece was 15 x 7.5 inch as required by the YouTube video. If your starting fabric is thick enough, you can cut it into 15 x 7.5 inch pieces.
This is the pattern I used: Youtube video https://www.youtube.com/watch?v=BCJcE-r7kcg&t=2s . One thing I saw wrong about other Youtube videos was they used pins which puts holes in the mask! No Pins Please. This definitely would reduce effectiveness. Use sewing clips as depicted in this video. It is very well done and easy to follow. Plus love the pocket.
Below is a chart showing how various fabrics compare when it comes to filtering micron sized particles . The CEO of Smart Filter, Paddy Robertson has several evidence based presentations with materials they have either tested in their lab or have references to published data. It appears to be trustworthy. https://smartairfilters.com/en/blog/diy-homemade-mask-protect-virus-coronavirus/
According to this website, out of all the household materials they experimented with, paper towels do not work very well (hence not shown here) but a double layer of dish towels was superior.
Based on these results, a mask made of 2 layers of tea/dish towel has the same filtering effects as a surgical face mask. Therefore, I decided to use a double layer of tea towel in the pocket of my homemade mask. That should be close to effectiveness of a surgical mask.
You can see that as the breathability goes up, the effectiveness goes down. Another reason why I like the mask with the pocket. You can personally vary the comfort of the mask with various inserts, knowing that with increases in effectiveness there is also an increase the airflow resistance. Increased air resistance makes every breath a little harder. Having 2 separate parts to the mask allows for more flexibility, easer to replace insert if a part wears out and easier to clean.
Pocket Insert Material. For the pocket of my face mask, I cut out 2 pieces of preshrunk dish towel to 5 x 5.5 inch pieces. The 2 layers were sewn together with a zigzag stitch, then a straight stitch around the edges. I will be experimenting with a Hepa filter when it arrives from Amazon in a few days. Will re-post then as to its comfort level compared with double layer of tea towel.
For the nose piece wire, I used aluminum jewelry wire. But 2 pieces of twist tie or gardening wire would work too. A small strip of foam was glued over the wire area for comfort. The elastic bands were 12 inches. Other substitutes for elastic bands are rubber bands, ribbon, shoe strings, cutting a wider elastic band into multiple strips.
How many hours can the same mask be worn and still be effective? Smartfilter tested N95 and Surgical masks for up to 3 hours and the masks were still performing well. Unknown how it performs beyond that time. For our pocket masks, you have the option to change out the tea towel filter at 3 hours. They tend to get moist from your breath so you would want to change it out.
How many times can I reuse my N95 mask? Smartfilter tested the an N95 mask for up to 30 days and there was only a slight decrease in performance. New mask, 20 days, 30 days respectively: 99.4%, 99.1%, 99.5%
Note: Having a beard reduces efficacy so an additional face shield is recommenced.
Part 3 will cover how to sanitize your reusable mask.