Thursday, May 21, 2020

Mask and face shield adventures

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EBY overtaking Stark as my favorite mask

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Stark v EBY v Wicking Neck Gaiter

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Proper Cloth

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Honeywell v Stark mask

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Winter PPE:

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I am very irritated about the way the press is treating the findings regarding wicking neck gaiters putting off droplets.  People: DROPLETS ARE NOT VIRUSES.   Wicking neck gaiters put of a lot of droplets by evaporation.  Droplets produced by evaporation are usually sterile.  The large numbers of droplets are not an indication that these masks are dangerous.  Quite the contrary: they may be much safer than other cloth masks.

Also, I am concerned about the condemnation of vented masks.  The vents on these masks direct droplets downwards.  They are going to have almost zero horizontal velocity.  This means that any exhaled viruses are likely to end up on the chest of the wearers, not in the air.  i am frustrated that the research is not looking at the role of horizontal velocity in the effectiveness of masks that are imperfect filters.


Here is an instagram video of me with my shop towel mask.

I got the SDS (safety data sheet) for the shop towels that I used and I didn't see anything dangerous on there, but they still give me a sore throat, so I don't like them. They were tested by someone at the University of North Carolina and they supposedly functioned better than standard surgical masks.  I did find that they fit my face well and didn't seem to have gaps around the edges.  I also found that I could breath fairly well through them.

I also tried the double towel mask, which is supposedly even more effective, but I found that I couldn't breathe well through it, which the video that talked about it warned about.

The following is a video about a plastic face shield that I ordered off of an instagram ad.  This was a dud.

Observations about soft plastic face shields

This is a video about a home made face mask that I got from a friend.

I've become convinced that the eyes are probably the primary way that COVID-19 would enter the body.

The mouth contains saliva, which is acid, and then you swallow a lot, which takes things down to the stomach, which is even more acid.  I've seen doctors claiming that the SARS-COV2 does not survive stomach acid.

The nose is pointing downwards, so, while you might inhale viruses, they won't normally just go flying in there.

The eyes, on the other hand, are just sitting right there in the front of your face where anything can fly in.  So I tried buying some prescription swim goggles, with the thought that they might be good for keeping viruses out of eyes.  These are the ones I ordered

They came quickly.  Given the very low price, I was astounded that I really could see very well.  They aren't as sophisticated as the glasses you pay more for.  They don't have astigmatism correction.  They don't account for pupilary distance, but for eight bucks they're pretty amazing.  If you can't afford glasses, you might try this.  Here's a photo of me with them on

I do find though that they're not really comfortable enough to wear all day.  They make my mug look oval, though, again, for the price, not so bad.  There was a weird adjustment going back to my regular glasses after wearing them.

Another issue that they have is that the plastic strap is sort of staticky and is a definite hair tangling hazard.  I accidentally pulled out a hunk of hair with them when I took them off. They probably work best over a swim cap.

If I ever dare go swimming again, I'm definitely going to use them.  I do think that germs travel pretty fast in water, so I don't think that swimming is going to be a good option this summer.  Still, as I said, for eight buck these have optical correction, UV protection, and anti-fog coating, which makes them pretty amazing to me -- and, since they are water tight, and definitely seal to my face, I do suspect they would keep virions out of my eyes.

Here's one about a face shield that I like

This is where I got this on amazon

I'm going to post more instagram videos soon about my adventures.

This is a video about putting buttons on your glasses to hang masks from.  I'm putting the link here just in case I want to find it again

This is about copper alloy devices for pushing buttons and opening doors

This video shows me with a turtle neck style mask with cooling, wicking material:

Athletic mask with vents.  Are vents anti-social?

The problem is that many people end up pulling their masks off their noses, even indoors, because they're having problems breathing.  The vents do improve the air quality inside the mask.  I feel that viruses escaping from the vents will still have lower horizontal velocity than if you had no mask, especially if the vents are pointed downwards as these are.  Moreover, most of your exhalation is going forward, not out the vents.  With reduced horizontal velocity, the viruses, or respiratory droplets containing them, will fall to the floor sooner.

I think the move to make the vents illegal is short sighted. A mask with vents is better than someone who pulls their mask off their nose, because they can't breathe.

I ended up not liking this mask too much, because if fogged up my glasses more than other masks.  Also it was hard to put on.

This is a "space mask" with nanofibers.  One concern I have with nanofibers is that they are fairly new and I'm not sure what their structural integrity is. Do they break off? If they break off, do I inhale them? If I inhale them, is that going to injure my lungs? 

Initially, I only felt slight irritation after wearing the Space Mask; however, after washing it, I noticed that it made my lips tingle, so I didn't want to wear it any more.  I was thinking that possibly the nanofibers might end up being a bit like asbestos.

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I bought this lovely butterfly mask on impulse, when I already had plenty of masks, but I really like it. I later realized that the reason that the shield was milky was that I had neglected to remove the protective cover.

This one is a more convenient substitute for a bandana.

So, here is me trying to "fix" PPE that has issues.

interesting youtube video testing masks

my comments on this youtube video

I was a physics major. I've been interested in reading the research of Dr. Lydia Bourouiba at MIT on the topic of the flight of respiratory droplets. Her models predict that, with intense breathing, respiratory droplets from the lungs could travel up to 27 feet. This is due to starting out with a horizontal velocity of 30-50 mph. It seems to me that our goal with cloth masks is not to create a sterile environment where there are no viruses. The goal should be to reduce the number of respiratory droplets AND to reduce their horizontal velocity. If they have no horizontal velocity, they will fall to the floor more quickly. In this video, you don't distinguish fog that has a high initial horizontal velocity from fog that has a low initial horizontal velocity. It seems to me that fog that is moving downward, e.g. from a mask with vents, is mostly going to land on the user's chest or the ground -- not out in the room where other people will inhale it. The situation with COVID-19 precautions is quite different from an operating room, where the surgeon is bending over the open body cavity of a patient. In the surgery situation, a few leaks could be very serious. In the common every day social situation, a few leaks, if of low horizontal velocity, are not going to be as important. I wish I would see more discussion of this aspect of the aerodynamics of contagion


Here's another episode in my ongoing experiments with PPE. I should say that I don't really think this setup would be adequate to go into a store -- but for hiking outside it's ok

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Addendum 210321 -- EBY mask