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COVID-19 Coronavirus Face Mask Sealer / Respirator

Many popular face masks don't work well against viruses, because (1) air goes around the face mask when breathing (total inward leakage), especially around the nose, so that viruses can leak in around the mask, and/or (2) the material does not filter the viruses well because the viruses are too small to filter, and do not stick to the fibers of most fabric materials very much. N95 and surgical masks are made from particular materials which capture viruses well. (3) Thirdly, there is also a shortage of surgical face masks and N95 respirators due to the COVID-19 coronavirus pandemic so many people must come up with a DIY home made mask made of the best available materials on hand, whereby our face mask sealer lets you quickly put any material inside -- just cut it to size with scissors and nothing else. However, any material should be chosen carefully.

This website discusses solutions to both of these issues -- inward leakage, and the best materials -- plus other important issues. It is written by a physicist who has read a lot of scientific research and understands these things in detail.

Even if you have NO MASKS AVAILABLE in stores near you, due to the pandemic shortage, we have a SOLUTION: Just put kitchen paper towel and facial tissue layers on your face, and our face mask sealer on top of them, to hold them SEALED to your face. Scientific studies have shown that layers of paper towel and facial tissue materials filter viruses of the size of COVID-19 coronavirus fairly well, nearly as good as surgical face mask material, and much better than many woven fabrics people are using! It's not just better than nothing, it's much better than nothing, and might prevent or reduce a viral dose so it's maybe not infective at all or causes milder symptoms.

To understand why, here is a step by step explanation:

Firstly, professionally manufactured surgical face masks, and also some N95 and N99 masks, have the problem of air leakage, which is known in scientific papers as "total inward leakage (TIL)", because air goes around the face mask, too, especially around the nose, instead of all through the face mask filter, so that viruses can easily bypass the filter:

Top & nose leakage:

Top & nose leakage:

Bottom leakage:

Side leakage:

Our Cross Strap Spongy Face Mask Sealer is designed to try to fix this problem with: (A) a soft spongy nose seal which is far more effective at sealing the top of the mask vs. the metal strip which comes with surgical masks, and the spongy seal is comfortable, (B) a strap under the chin to seal the bottom and 2 sides of the mask, this strap going around the top of the head, and (C) a flat strap behind the back of the head instead of a band around the ears, as a strap around the back can be tighter while still comfortable to better seal the mask, as ears can get sore from bands otherwise, whereby sealing the top part around the nose with the spongy seal should be a little bit tight.

Overview:

Seal top & nose:

Seal bottom:

Seal the side:

The Cross Strap Spongy Face Mask Sealer is not intended to be used alone, it is intended to be used on top of something else, such as a surgical mask to seal it. You can use any material inside, but we strongly recommend you know what materials filter viruses well, and which ones do not. This materials issue is covered below and in detail in another section of this website, but in short, it is hard to beat N95 and standard surgical mask materials, and the main big problem with surgical masks has been sealing them around the face.

Secondly, this website covers good materials for the internal mask under the Cross Strap Spongy Face Mask Sealer. For example, you can see that sweatshirts, t-shirts, towels, and scarves do not work well when compared to N95 materials or surgical masks.

Source: Simple Respiratory Protection—Evaluation of the Filtration Performance of Cloth Masks and Common Fabric Materials Against 20–1000 nm Size Particles
Samy Rengasamy, Benjamin Eimer, Ronald E. Shaffer
The Annals of Occupational Hygiene, Volume 54, Issue 7, October 2010, Pages 789–798Rengasamy-1
Source images edited by the author of this page to show ~100 nm size particles and for brevity.

The above graph is for a sealed N95 face mask. Many N95 and N99 masks also have inward leaks of air around the nose, so that they are really not 95% or 99% effective. If you have 25% or more air leakage, then it's like an N75 mask or worse. The mask can still be advertised as N95 because it may include N95 certified material, but that may not mean you have 95% protection, especially if it is not sealed. The face mask material has some resistance to air flow, so a lot of air with viruses can simply take the easy path around the filter if there is a leak, especially around the nose, but also other parts around the face for many masks I've seen. If a mask just has an insertable N95 filter but otherwise leaks through other fabrics, then it's questionable.

Ordinary masks sold at stores usually have a metal strip which you bend around your nose to reduce inward air leakage, but there can still be a lot of leakage. A metal nose strip is not something to rely on! For example, see the Manikin tests below.

Manikin studies show that a surgical face mask typically allows 20% to 35% inward leakage, which is the main reason they don't protect you well when used alone out of the box. However, how does surgical mask material compare to N95 material when sealed? After all, they're both made from similar materials to trap microparticles (nonwoven polypropylene), so they should compare well. Here are laboratory results of testing surgical masks which were properly sealed, showing only a 3% to 7% leakage against particles the size of COVID-19 coronaviruses which is about 100 nanometers, with sealed on the left, and unsealed with inward leakage on a manikin on the right:


Source: Effect of Particle Size on the Performance of an N95 Filtering Facepiece Respirator and a Surgical Mask at Various Breathing Conditions
in Aerosol Science and Technology 47(11)
Authors: Xinjian Kevin He, Tiina Reponen, Roy T. McKay, Sergey A GrinshpunManikin-tests-1
The image above is a mix of the graphical data and information of the authors above and the creator of this website.
(Humans breathe about 5 to 8 liters/minute when resting, and around 12 liters/minute during light activity. These tests were done at 15 liters per minute, and various breathing rates for the different lines.)

Our Cross Strap Spongy face mask sealer is something you wear on top of a surgical face mask, or on top of an N95 face mask, to create a much better seal, to try to change results from the rightside to the leftside. You can take your cheap surgical mask and make it work much better by putting our mask on top. It has these features:

  1. A soft foam material around the nose, which pushes the face mask against the face. This prevents air leakage around the nose. It is also MUCH more comfortable than the metal strip. This seals the TOP of the face mask.

  2. A second elastic band to go under the jaw and around the cheeks, to seal the BOTTOM and 2 SIDES of the mask.

  3. Altogether, two elastic bands, one for the top, and one for the bottom and sides, approximately 90 degrees to each other. These elastic bands go around the back of the head, not around the ears, for a tighter seal and better comfort. These elastic bands can be adjusted to fit the person's head size.

It is important to understand that the Cross Strap Spongy Face Mask Sealer is not intended to be used alone, and is instead intended to be used with another face mask, usually a surgical mask. You first put on a surgical mask. In the photos above, you can see the surgical mask underneath, put on with loops around the ear. Our mask goes on top of that, and has no loops around the ears.

(The metal nose strip which comes with surgical masks may be uncomfortable, so you can just put it on upside down, with the metal strip under the chin instead, if you use our external face mask sealer. Also, after our mask has secured the surgical mask, you can optionally remove the surgical mask's loops around the ears if they're uncomfortable.)

We have the option of shipping the Cross Strap Spongy Mask together with a surgical mask or an N95 or N99 or other quality material if there is sufficient stock of surgical masks or N95 or N99 material available, but because stocks are in short supply during an epidemic, the Cross Strap Spongy Face Mask is usually shipped alone, and can instead be used with masks which people already have, such as a surgical mask or an N95 or N99 mask for which you want better sealing and comfort. If you want to put two surgical masks under the Cross Strap Spongy Face Mask Sealer, for double protection, that's okay, too.

Actually, due to shortages, if you simply have no access to a surgical face mask or N95 material, then our face mask sealer can be used with any material. You don't need to buy a sewing machine and straps to make a home made mask, you can just put any rectangular cut of material inside our mask. You don't need ear loops or anything else. Just a rectangular piece of material. The face mask sealer will hold it in place on your face.

Now for a very interesting finding in laboratory tests: Layers of kitchen paper towel plus facial tissue materials work nearly as well as surgical masks, and better than many fabrics! Therefore, you can just tear off a couple of paper towels, combine them with a facial tissue, stack them and cut them to size, then use the face mask sealer to hold them in place around your face.

Researchers in Hong Kong, due to a face mask shortage, were testing alternative materials. They found pretty much what other researchers found, that ordinary woven cloth materials did not trap viruses very well. However, when they tested just paper towels and facial tissues, they found out some surprising results. As shown in the graph below, a layered mask of "kitchen papers" plus 1 "tissue paper" worked nearly as well as a surgical mask in their particular experiments, as regards particles around the size of the COVID-19 coronavirus! Wow!


Source: A collaboration of the University of Hong Kong, Shenzhen Hospital, Consumer Council, Department of Architecture and Civil Engineering, The City University of Hong Kong, the Hong Kong Consumer Council, the Hong Kong Applied Science and Technology Research Institute (ASTRI), and the Hong Kong Science and Technology Parks Corporation (HKSTP).HK-collab

It's not just better than nothing. It's actually pretty good! It's also cheap, abundant even during a pandemic, and quick & easy!

So I tried it, with 2 layers of good ScottTM paper towels on the outside and one 3-ply KleenexTM facial tissue, and oh my goodness, it worked great. It was not difficult to breathe through, it was comfortable to wear for a long time, and I had the whole thing ready in minutes after getting my hands on paper towels and facial tissue:




In any case, keep in mind that sealing whatever you have is very important. You can get filters anywhere -- surgical face masks, N95 face masks, paper towels and facial tissue, or some other material -- but their effectiveness in protecting you against viruses depends a lot on the SEAL of the filter around your nose and face.

Also, comfort is important, and our Cross Strap Spongy Face Mask Sealer can seal your filter(s) very comfortably so you can wear them a long time.

Another advantage of sealing is: People who wear eyeglasses can benefit by the elimination of "fogging" of our eyeglasses which happens when wearing an unsealed mask. Back when I wore unsealed face masks, fogging of my glasses was an annoyance, and I had to remove my face mask many times to be able to see. This was because when I breathed out, the leakage from the top of the mask fogged my eyeglasses. Once I applied a spongy nose seal, the fogging went away. This result may encourage more people who wear eyeglasses to use face masks more.

I am aware that many other people who wear glasses have taken off their face mask for this reason -- they cannot see because their eyeglasses fog up. The cannot work or do many other things with a face mask on. This is a solution, so you can have your face mask and your eyeglasses on, too.


The Cross Strap Spongy Face Mask Sealer was designed by American physicist Mark Prado in Thailand. The English version of this website is written by Mark Prado, his daughter Angela Prado worked on the Thai translation, and his wife Kanta Prado helps others to understand and manufacture the masks.

This website also covers topics such as the effectiveness of different mask materials, the poor design and effectiveness of many masks on the market, and how to disinfect and clean masks for reuse. Besides our own mask, we try to give general guidance and solutions about protecting yourselves from the COVID-19 coronavirus which originated in Wuhan, China.

This is just a brief page. It is recommended that you next read these important pages:

  1. Air goes around the face mask when breathing (total inward leakage)

  2. Face mask materials which truly filter viruses well

There are additional sections on this website covering various topics, but I recommend you not miss the above two sections.

Also, if you like this website, please just drop me a line to let me know. It's a lot of time and effort instead of doing other things, whereby feedback is encouraging.


References and Footnotes:
Ref: HK-collab

Source: Hong Kong DIY tissue paper mask
The University of Hong Kong – Shenzhen Hospital
Department of Architecture and Civil Engineering, The City University of Hong Kong
Consumer Council of Hong Kong
Hong Kong Applied Science and Technology Research Institute (ASTRI)
Hong Kong Science and Technology Parks Corporation (HKSTP)

Ref: Manikin-tests-1

Source: Effect of Particle Size on the Performance of an N95 Filtering Facepiece Respirator and a Surgical Mask at Various Breathing Conditions
Parent publication: Aerosol Science and Technology 47(11)
Authors: Xinjian Kevin He, Tiina Reponen, Roy T. McKay, Sergey A Grinshpun

Ref: Rengasamy-1

Source: Simple Respiratory Protection—Evaluation of the Filtration Performance of Cloth Masks and Common Fabric Materials Against 20–1000 nm Size Particles
Parent publication: Aerosol Science and Technology 47(11)
Authors: Xinjian Kevin He, Tiina Reponen, Roy T. McKay, Sergey A Grinshpun



For a directory of pages on this website, please see our SiteMap, where you might find some more things of interest.

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Parts of this website are derived from my pollution mask work in 2019.

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