Sewing DIY Cloth Surgical-style Face Masks

This mask design fits very well. It is double layer cotton, with a space between for filter material. The nose bridge has a metal insert for forming around your nose. Straps go around your neck and head. Photo1 by Don Tai

This mask design fits very well. It is double layer cotton, with a space between for filter material. The nose bridge has a metal insert for forming around your nose. Straps go around your neck and head. Photo1 by Don Tai

We don’t as yet have an epidemic with the corona virus CoVid-19, from originally from Wuhan, China, but i thought it prudent to research how to sew up some surgical-style face masks, just in case. These home made masks can possibly match the surgical-style mask.

These face masks are nowhere near as good a filter as an N95. The material to make an N95 is quite expensive and specialized. The N95 also needs to be air tight. N95 masks need to be certified. Wearers also need training and a fit test. No cloth mask, nor any surgical style mask meets this criteria. If you work in a hospital or are that close to a person with the virus, use an N95. This study Simple Respiratory Protection—Evaluation of the Filtration Performance of Cloth Masks and CommonFabric Materials Against 20–1000 nm Size Particles shows that these DIY cloth masks are nowhere near as good as the N95. The N95 standard is not only much more expensive, but if in high demand, such as a pandemic, will be difficult to obtain and may deprive health care workers of necessary stock.

The fabric materials tested in our study might also be expected to provide marginal levels of respiratory protection for 20–1000 nm aerosols (droplet nuclei). Fabric materials may provide respiratory protection levels (i.e. total inward leakage) similar to the levels obtained using some surgical masks,which have been measured to be, 10 (Oberg and Brosseau, 2008). Thus, the use of improvised fabric materials may be of some value compared to no protection at all when respirators are not available. Moreover, fabric materials would not suffer from limited supplies unlike respirators and surgical masks for emergency protection….

The penetration levels obtained for fabric materials against both polydisperse and monodisperse aerosols were much higher than the value for the control N95 respirator filter media but were in the range found for some surgical masks in previous studies.

Which type of mask is appropriate for around town daily use is controversial. Surgical style masks are intended to keep the germs of the wearer out of the open wounds of a patient while doing a surgery. They are not intended to protect the wearer from outside viruses. Most are disposable and should be discarded after 30 minutes of wear, when it gets wet and can no longer do its job. These are not the conditions for daily use for shopping. That said, if the virus is aerosolized, the mask may prevent the virus from entering the mouth or nose, but offer no protection for the eyes. The mask can protect the wearer from transferring virus from touched surfaces, to her hands to her face or nose. In this use case, an N95 is overkill, will not last long, and is expensive. A surgical mask for daily shopping use also seems inappropriate for a shopping use case.

The advantages of a DIY cloth mask is that for daily use it should be good enough. Aerosolized droplets will be bigger than the virus and should be caught by the cloth. As well, if your eyes are uncovered this provides an entry for the virus. Additional filter material can be added to the DIY mask. The DIY mask will be much more breathable and just as comfortable as a surgical mask. The cloth mask can be disinfected, washed and used multiple times. They are inexpensive and quick to make and can be sewn in many different cloth designs, making them fun to wear. If they are fun to wear then people might be more apt to wear them.

This mask design fits very well. It is double layer cotton, with a space between for filter material. The nose bridge has a metal insert for forming around your nose. Straps go around your neck and head. Photo1 by Don Tai

This mask design fits very well. It is double layer cotton, with a space between for filter material. The nose bridge has a metal insert for forming around your nose. Straps go around your neck and head. Photo1 by Don Tai

I used this design, along with her .pdf. The design fits well and is pretty easy to sew up. I actually just used loose material I had around. I made a cardboard pattern, for the adult size. The design requires a 1/4″ seam allowance, as well as 1″ for the side loops.

This video How to Sew the VERY BEST Fitted Fabric Face Mask with Filter Pocket and Nose Support has the very same design, which includes a pocket for an inner extra filter, but has 3 layers to breath through.

There is the outer layer and the inner layer. Each layer requires 2 copies of the pattern, sewn together on the longest curved edge. I also topstitched the outer layer, but did not for the inner layer. Put the two sides together, good side in, and stitch the top and bottom sides. Then you turn the mask inside out and top stitch the top and bottom down. Your mask is now essentially complete. The two sides still require work.

This mask design fits very well. It is double layer cotton, with a space between for filter material. The nose bridge has a metal insert for forming around your nose. Straps go around your neck and head. Photo2 by Don Tai

This mask design fits very well. It is double layer cotton, with a space between for filter material. The nose bridge has a metal insert for forming around your nose. Straps go around your neck and head. Photo2 by Don Tai

The choice of materials is pretty critical. I used old t-shirt material in cotton for the inner layer, because it would be comfortable to the skin. Comfortable it is, but it is porous and would let in larger air particles. There is a tradeoff between comfort, porosity, breathability and protection. The more porous the more breathable but less protective. The outer layer should be a tighter weave, which will give you better protection, but will not be as breathable.

Before you sew up the sides there is a decision to make. You could sew the sides in a loop, put an elastic cord through and be done with it. A single cord that goes around the head from ear to ear, and then across the neck, from side to side, will reduce friction on the ears, increasing comfort. I used 32″ of elastic for mine. The alternative is to leave the sides open in order to slip in more filtering material, such as tissue paper, or even a surgical mask. you can then use the DIY mast as the outer and inner layer, sandwiching the surgical mask in between. If you do this then the two sides must be kept open and the loops must only use the outer layer.

This mask design fits very well. It is double layer cotton, with a space between for filter material. The nose bridge has a metal insert for forming around your nose. Straps go around your neck and head. Photo3 by Don Tai

This mask design fits very well. It is double layer cotton, with a space between for filter material. The nose bridge has a metal insert for forming around your nose. Straps go around your neck and head. Photo3 by Don Tai

The fit is quite good, with the exception of the two sides of your nose. I could tighten this up with a wire nose bridge, but what happens when you wash it? The wire might rust. As the material will be quite porous anyway, maybe there is no need. I’ll need to think about this. As an upgrade I added 1/4″ channel in the nose area for a 5″ wire. The two ends are rounded. I can get the wire out if I wish to change it.

Disinfecting clothing
This article” has tips on how to disinfect clothing. Interestingly it recommends white cotton because it can withstand the hard disinfecting chemicals.

Normal laundry procedures should be using hot water (100 degrees F. or above with 140 degrees F being optimal), a disinfectant product following product directions, and finally, a high heat machine drying cycle…

When someone is ill, opt for white 100 percent cotton sheets. Why? They may be boring but are easy to disinfect with hot water. Sheets that are bright colors and a synthetic blend cannot stand up to the rigors of disinfecting chemicals.

US CDC disinfection information also recommends diluted bleach.

Disinfectant: 5tbsp bleach/4L water

More simply, to kill the virus, simply wash with soap and water. This breaks down the outer lipid/fatty layer of the virus and it does. This is simpler and less caustic than bleach or other disinfectant.

Improvements:
Make the inner layer shorter at the ends, edges sewn down to the wrong sides. This allows the outer layer’s edge to be folded over for the elastic, but allow extra filtering medium to be inserted into the middle.
Serge the outer layer’s ends. This reduces the bulk when you fold it over for the elastic.

Filter Material
Non-woven polypropylene, the material used in reusable shopping bags, has come up many times. This video 2’35” quotes a Dr Jorhay Zuniga, from Chile, on the Open Source COVID19 Medical Supplies thread, as saying the material will block 96.4% of 1 micron particles and 89.5% effective for 0.2 microns.

Jorge Zuniga
March 21 at 9:05 PM
NanoHack
NanoHack Mask is a last resort device with the purpose of offering protection from airborne particles and prevent spreading liquid contaminating the airways. Published data1 has shown that the filtration materials used by NanoHack (polypropylene, the same material used in surgical masks) achieves a filtration efficiency of 96.4% for microorganisms of 1 micron and 89.5% for microorganisms of 0.02 microns1.

1. Anna Davies, et al. Testing the Efficacy of Homemade Masks: Would They Protect in an Influenza Pandemic? Disaster Medicine and Public Health Preparedness, Available on CJO 2013 doi:10.1017/dmp.2013.43

The actual quoted article cites that t-shirt material is only 50% as effective as a surgical mask.

Fit tested Sewn Mask
Here’s a Youtube vid about a doc who used a University of Florida design with Halyard H600 material. The nose bridge is 5″ of 16 ga wire. Interesting testing procedure.

Addendum 2020 Mar 27 A Sewing Army, Making Masks for America

But a 2008 study on the use of both commercial and home-made masks by the general public to ward off influenza, published in the journal PLoS, found that “all types of masks reduced aerosol exposure”.

Although home-made masks performed less well, “any type of general mask use is likely to decrease viral exposure and infection risk on a population level, in spite of imperfect fit and imperfect adherence, personal respirators providing most protection,” the researchers from the Dutch National Institute for Public Health and the Environment concluded. source

Professional and Home-Made Face Masks Reduce Exposure to Respiratory Infections among the General Population

face mask pattern from craftpassion.com

Fogging Glasses
We had an issue with fogging of glasses. This was greatly minimized when I added a metal wire to the nose piece, which greatly limits the air escaping from your exhale. How to stop a face mask fogging up your glasses

A flexible “nose”
Some masks come with a metal nose clip that allows the wearer to limit the amount of moisture that comes in or out of the mask. If you’re sewing home-made masks, you can use flexible objects like hair grips, paper clips or pipe cleaners to create a fitted “nose”.

A HK mask design

HK Mask is a reusable cloth mask with a disposable middle layer filter. It was invented by Dr. K. Kwong during the outbreak of COVID-19 in early 2020.

The design of HK Mask is referred by that of 3-layer surgical mask in the market. The HK Mask is composited with a disposable middle layer filter which is sandwiched by a cloth mask as the outer and inner layers. There are a number of material chosen for the middle layer filter ranging from Kitchen Towel Paper to Nanofilter.

The filtration efficiency of a piece of kitchen towel paper is close to that of N70. The mask can be safely used after replacing a new middle layer filter to a cleaning and sterilizing the inner and outer layer cloth…

The FILTER can be two pieces of pocket tissue paper or one piece of kitchen tissue paper.
The mask can be made of any fabrics, but the thinner the better.

This mask design uses an inner pocket where you can add a filter layer. The filter layer sticks out the bottom 2 corners as well as the top. It has both ear elastics as well as ties at the back of the head and neck. The advantage is that the filter material is rectangular and needs no cutting nor sewing.

CuMask+, from the Hong Kong government
This mask design has a built-in filter that is washable 60 times, after which you can replace the filter. The filter material has woven copper that claims to attract small particles. The HK government will be providing a mask for each resident for free. This is a great idea, and should reduce the demand for single use surgical masks.

The CUMask+ from Hong Kong, is a washable, reusable face mask, provided free of charge to all HK residents. The filter material is washable, has copper fibers that attract small particles, and is replaceable. Great ideas from HK, and good government policy. Demand for single use surgical and N95 masks will be markedly reduced. Photo from SCMP.

The CUMask+ from Hong Kong, is a washable, reusable face mask, provided free of charge to all HK residents. The filter material is washable, has copper fibers that attract small particles, and is replaceable. Great ideas from HK, and good government policy. Demand for single use surgical and N95 masks will be markedly reduced. Photo from SCMP.

HK CuMask Review. There are other reviews but are in Cantonese. One issue that came up with all reviews is that the mask has no nose bridge, leaving two open areas on either side of the nose. This lets in air when breathing, thus reduces the efficacy but eases breathing capability.

What we’ve learned after making 167,000 masks!: Uses the craftpassion pattern for a fitted mask
A different fitted mask design by Jesse Killion

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