Unsuitable Materials for DIY Coronavirus Masks

[Jarvis323]

As you all know, everyone is in a mad DIY mask rush right now as it has become an official recommendation. Some have been searching for the best materials, and some of them have been found to be great filters. However, these non-standard mask materials are also not tested and evaluated for use as a respirator, where inhalation is a major consideration. Even worse, it is typical for hazardous chemicals like formaldehyde to be used in these classes of textiles (e.g. non-woven) as a binder, yet disclosure of levels of formaldehyde are not required by default for textiles, and laws limiting those levels are based on intended use (shop towels for example wouldn't be strictly regulated).

I'm curious about peoples thoughts; how can best incorporate proper caution and safety evaluation into the national efforts worldwide to prevent harm? It seems to be a missing part of the grassroots emergency effort.

https://www.businessinsider.com/homemade-mask-using-hydro-knit-shop-towel-filters-better-2020-4
https://www.lung.org/clean-air/at-home/indoor-air-pollutants/formaldehyde
https://www.gao.gov/new.items/d10875.pdf

 

[jedishrfu]

I would steer clear of air conditioning filters for fear of inhaling asbestos fibers or something similar. Some HVAC filters are made of spun fiberglass:

https://davisac.com/article/air-filters-understanding-function-choose-right-one

and fiberglass can be an irritant if touched or inhaled.

http://www.idph.state.il.us/envhealth/factsheets/fiberglass.htm

I've seen some masks that use paper towel materials:

https://smartairfilters.com/en/blog/paper-towel-effective-against-viruses-diy-mask/

 

[Tom.G]

Don't use synthetic materials, polyester, etc, for either the material or filter. The virus can live for up to 3 days on plastics and on metal.

Here is a site that suggests using a paper coffee filter. Better use the unbleached ones, some white (bleached) ones can even give the coffee a bad taste!

https://www.theguardian.com/us-news/2020/apr/06/how-to-make-no-sew-face-mask-coronavirus

 

[Jarvis323]

I would steer clear of air conditioning filters for fear of inhaling asbestos fibers or something similar. Some HVAC filters are made of spun fiberglass:

https://davisac.com/article/air-filters-understanding-function-choose-right-one

and fiberglass can be an irritant if touched or inhaled.

http://www.idph.state.il.us/envhealth/factsheets/fiberglass.htm

I've seen some masks that use paper towel materials:

https://smartairfilters.com/en/blog/paper-towel-effective-against-viruses-diy-mask/

I would be weary of paper towels before testing. It's a good example of a product with incentive to manufacture using toxic chemicals only within the required safety level for intended use (wiping things down), while huffing it daily for hours at a time would be a different story.

A lot of materials might seem fine, but actually may not be for use as a respirator. The EPA even recommends washing permanent press clothing before wearing due to the formaldehyde based treatments. Almost any kind of textile, or paper like product should be considered carefully for safety of long term inhalation, and I would guess that a lot of them wouldn't be approved by regulatory agencies.

Maybe I'm being a little too analytical, I don't know.

 

[chemisttree]

The Suay Sew Shop is making cotton masks incorporating blue shop towels to enhance effectiveness (measured by particle counter). They found two versions of blue shop towels to be effective at filtering down to 0.3 micron and at least one that wasn’t. They actually tested their towel materials! Very cool!

 

[Jarvis323]

The Suay Sew Shop is making cotton masks incorporating blue shop towels to enhance effectiveness (measured by particle counter). They found two versions of blue shop towels to be effective at filtering down to 0.3 micron and at least one that wasn’t. They actually tested their towel materials! Very cool!

Yes, but how do we know those towels are safe to inhale for extended periods. They are the exact type of materials you would expect not to be. Maybe the trade-off is potentially not getting COVID-19 in exchange for potentially getting cancer? I'm hoping to figure this out soon.

 

[anorlunda]

Yes, but how do we know those towels are safe to inhale for extended periods. They are the exact type of materials you would expect not to be. Maybe the trade-off is potentially not getting COVID-19 in exchange for potentially getting cancer? I'm hoping to figure this out soon.

It might be easy to drive ourselves crazy with fears. Pay attention. Resist exaggeration of the risks in your mind. It is directly harmful to your health to do so. See nocebo effect.

I would say "extended period" for cancer purposes is closer to 24x7 for 1 year. That is not a scientific estimate because is cites no source, nor does it even name the hazard. But here is a real life example from personal experience:

My father in law was an asbestos worker. He was even the steward of the asbestos workers union. He died of mesothelioma 5 days after retirement. But it took 90000 hours of close-up exposure to that very hazardous asbestos to kill him. (40 hours per week x 50 weeks x 45 years). For him, that was "extended period."

I believe the nocebo effect is a greater risk than choice of materials for masks.

 

[chemisttree]

Yes, but how do we know those towels are safe to inhale for extended periods. They are the exact type of materials you would expect not to be. Maybe the trade-off is potentially not getting COVID-19 in exchange for potentially getting cancer? I'm hoping to figure this out soon.

Why do you think this?

 

[Jarvis323]

Why do you think this?

Because they are a cheap paper-like product designed to be absorbsnt, soft, heavy duty, have wet strength durability, and solvent resistance, and are not regulated with prolonged inhalation in mind. Those properties, for these kinds are products, are achieved commonly through use of formaldehyde based binders or treatments, and other unacceptable chemicals for inhalation. I'm just saying, this isn't a good thing to bet on being safe, and the necessary information to make a determination doesn't seem to be disclosed either.

https://en.m.wikipedia.org/wiki/Wet_strength#Wet_strength_chemicals

https://www.lung.org/clean-air/at-home/indoor-air-pollutants/formaldehyde

 

[Jarvis323]

I couldn't find much, but it seems one of the relevant processes is double re-creping. I found a patent from 2003 that gives insight into the issue of formaldehyde. I don't know what is used in any specific products.

BACKGROUND OF THE INVENTION
[0002]
Liquid absorbent products such as paper towels, tissue paper, feminine hygiene products, industrial wipers, food service wipers, napkins, medical pads, and other similar products are designed to include several important properties. For example, the products should generally have good bulk, a soft feel and should be highly absorbent. The products should also have strength even when wet and should resist tearing. Furthermore, many products should also have good stretch characteristics, should be abrasion resistant, and should not deteriorate in the environment in which they are used.
[0003]
One process that has proven to be very successful in producing soft, absorbent, single ply fibrous webs having a laminate like structure that are particularly well suited for use as wiping products is disclosed in U.S. Pat. No. 3,879,257 to Gentile, et al., which is incorporated by reference in its entirety.
[0004]
The fibrous webs disclosed in Gentile et al. are formed from an aqueous slurry of principally lignocellulosic fibers under conditions that reduce interfiber bonding. A bonding material or creping composition such as, for example, a latex elastomeric composition, is applied to a first surface of the web in a spaced-apart pattern. The bonding material provides strength to the web as well as abrasion resistance to the surface of the web.
[0005]
Once the bonding material is applied to the first side of the web, the web can be brought into contact with a creping surface. Specifically, the web will adhere to the creping surface according to the application pattern of the bonding material. The web is then creped from the creping surface with a doctor blade. Creping the web greatly disrupts the fibers within the web thereby increasing the softness, absorbency, and bulk of the web.
[0006]
In one embodiment disclosed in Gentile et al., both sides of the web are creped after the bonding material has been applied. Thus, the bonding material can be applied in a manner similar to that of the first side to the opposite side of the web to provide additional strength and abrasion resistance.
[0007]
Bonding materials used in creping fibrous webs typically include a crosslinkable polymer that contains functional groups, such as n-methylol acrylamide, that are crosslinked in the presence of an acid catalyst during the creping process. However, the crosslinking reaction often generates formaldehyde, such as by a condensation reaction, which is absorbed by the fibers of the web and remains resident in the resulting creped product.
[0008]
Increasingly, regulations and health concerns have mandated lower and lower formaldehyde levels in products. Formaldehyde absorb by the fibers (“free formaldehyde”) can be released to the surrounding environment at a pH of 7 or greater such as when the fibers are wetted. Additionally, the released formaldehyde can react with other compounds in or on the fibers to form undesirable and/or noxious odors. For example, when formaldehyde reacts with ammonia a methylamine compound having a distinctly fish-like odor can be produced.
[0009]
Some manufacturers of creping materials have attempted to reduce the level of formaldehyde generated during crosslinking by adjusting the degree of crosslinking and by utilizing various acid catalysts. Others have attempted to control formaldehyde emissions from creped materials by including high surface area pigments, such as diatomaceous earth, or malodor absorbers, such as certain organic acids. However, many of these treatments are sprayed or coated onto the surface of the creped product as a post-forming treatment thereby adding an additional production step.
[0010]
With the foregoing in mind, there is a need or desire for a bonding material or creping composition that produces a lower amount of free formaldehyde residue in a creped material. There is also a need or desire for a creped material that includes a lower level of free formaldehyde and may be produced efficiently and economically.
[0011]
Therefore, it is a feature and an advantage of the present invention to provide a creping composition that produces a reduced level of free formaldehyde residue in a creped material. It is a further feature and advantage to provide a creped material including the creping composition of the present invention having a lower level of free formaldehyde residue than a comparable creped material.

https://patents.google.com/patent/US20040118534

 

[Dullard]

Relax, sir. How much formaldehyde could actually be in a paper towel? Breathing through it should sparge it pretty quickly. People in the U.S. used to live in new dwellings (mobile homes, particularly) where your eyes would water from the formaldehyde in the carpet, fabrics, paneling, etc. Didn't effect me none. The amount present in consumer products (now) is very low (compared to that). You will die of something. Formaldehyde probably won't be it.

 

[Swamp Thing]

What if we allow a batch of masks to out-gas in an oven for a couple of hours, maybe at 70 or 80 deg. C? Maybe even in a partial vacuum to draw out the volatile stuff?

This is just a starting point for brainstorming - there could be other things one could do to remove most of the bad stuff before use.

Some of the options may not be practicable in a regular household setting, but a small group of "makers" could set up a small facility to process the fabricated masks before use...

Edit: In "other things", consider putting some activated charcoal in the oven along with the masks.

Edit: or put the activated charcoal in a small separate chamber that we keep at room temp, while we pump some fraction of the main chamber's air through the charcoal.

 

[Jarvis323]

Relax, sir. How much formaldehyde could actually be in a paper towel? Breathing through it should sparge it pretty quickly. People in the U.S. used to live in new dwellings (mobile homes, particularly) where your eyes would water from the formaldehyde in the carpet, fabrics, paneling, etc. Didn't effect me none. The amount present in consumer products (now) is very low (compared to that). You will die of something. Formaldehyde probably won't be it.

Paper towels are in a class of products that this concern is relevant to. Paper towels do emit formaldehyde at low levels. I would worry more about the products in that class that are designed for higher performance an less human contact.

 

[TeethWhitener]

Paper towels do emit formaldehyde at low levels.

Are these levels harmful to human health? Most living things (including us) emit formaldehyde to some extent. It's difficult to find any information about formaldehyde levels in paper towels, and google searches are heavily populated with titles like "12 deadly toxins that are killing your children RIGHT NOW! (click here to subscribe)."

 

[TeethWhitener]

This article in CEN discusses cloth masks.

If you're really worried about formaldehyde, why not just dampen your paper towel with an OTC 3% hydrogen peroxide solution? It'll oxidize all the formaldehyde, probably to CO₂ and water, given that it will be in massive excess.

 

[Jarvis323]

Just to be clear, I'm not worrying about this for myself, I'm trying to get to the bottom of it for the sake of the public. If I knew the precise safety info I could help inform those who are mass producing emergency PPE for health care workers, nursing homes, etc. The go-fund me that is making hundreds of thousands based on disposable shop towels is an example. That in particular raised a red flag, that had me concerned for both the wearers (e.g. maybe a nurse ends up wearing these things for 12 hours at a time per day), but also the volunteers who are trying to help but don't know if what they are producing is even safe. Some people have formaldehyde sensitivity as well (at low levels) and would benefit from knowing what they are huffing.

To me it's a no brainer, make millions of things people will be breathing through for extended periods, test those things for safety. The fact that these types of materials are known to emit dangerous chemicals is just a stronger reason. Formaldehyde is only one obvious risk, but there could be more.

I've reached out to a few professionals about whether they could volunteer to help with safety evaluation, so we'll see. It seems to be the case that independent direct testing for the intended use case is required. For example, forcing warm moist air through the material at constant rate for a few hours into a small enclosed container with VOC testing equipment reading the levels; or some kind of simulated environment.

I don't believe armchair speculation will be of much use beyond experiment design. The chemical contents and emissions of these products are proprietary and undisclosed.

 

[chemisttree]

Just to be clear, I'm not worrying about this for myself, I'm trying to get to the bottom of it for the sake of the public. If I knew the precise safety info I could help inform those who are mass producing emergency PPE for health care workers, nursing homes, etc. The go-fund me that is making hundreds of thousands based on disposable shop towels is an example. That in particular raised a red flag, that had me concerned for both the wearers (e.g. maybe a nurse ends up wearing these things for 12 hours at a time per day), but also the volunteers who are trying to help but don't know if what they are producing is even safe. Some people have formaldehyde sensitivity as well (at low levels) and would benefit from knowing what they are huffing.

To me it's a no brainer, make millions of things people will be breathing through for extended periods, test those things for safety. The fact that these types of materials are known to emit dangerous chemicals is just a stronger reason. Formaldehyde is only one obvious risk, but there could be more.

I've reached out to a few professionals about whether they could volunteer to help with safety evaluation, so we'll see. It seems to be the case that independent direct testing for the intended use case is required. For example, forcing warm moist air through the material at constant rate for a few hours into a small enclosed container with VOC testing equipment reading the levels; or some kind of simulated environment.

I don't believe armchair speculation will be of much use beyond experiment design. The chemical contents and emissions of these products are proprietary and undisclosed.

Then you should get on your horse and protest the use of N95 masks...
https://journals.lww.com/dermatitis...ons_Following_Use_of_N95_Facial_Masks.13.aspx

 

[Mister Perfessor]

Then you should get on your horse and protest the use of N95 masks...
https://journals.lww.com/dermatitis...ons_Following_Use_of_N95_Facial_Masks.13.aspx

I read the entirety of that article. It does not appear to be so cut & dry that all N95 masks in general ought to be regarded as low-level sources of formaldehyde. In fact, that article makes me think that the professionally made masks might have a random choice of low-level or zero-level amounts of formaldehyde in the materials they chose to manufacture out of. And, that maybe these consumer products we may choose from could be rated for their ability to be called hypoallergenic

I myself do not have a 'sky is falling' level of concern about the OP's question here. I just think it would be useful to establish whether or not any given material is safe enough, or not safe enough. I myself would be more inclined to worry about particle size & blocking characteristics than formaldehyde, but it couldn't hurt to test a sample at least once just to eliminate the concern

So, would a DIY home user test kit be appropriate to answer the question? - https://www.amazon.com/dp/B01LC43RMK/?tag=pfamazon01-20

 

[Lnewqban]

https://smartairfilters.com/en/blog/best-materials-make-diy-face-mask-virus/?rel=1

 

[Mister Perfessor]

https://smartairfilters.com/en/blog/best-materials-make-diy-face-mask-virus/?rel=1

I read that cambridge report. Suay Sew Shop is trying to do the same kind of testing using some more interesting fabric choices than just plain cotton. But the testing will cost around $40,000

 

[Tom.G]

https://www.ncbi.nlm.nih.gov/pubmed/31479137
And this more recent one confirming no significant difference of laboratory-confirmed Influenza between the N95 and the paper Medical Mask.

Oops! A bunch of posts (10) disappeared while editing this. Oh well.

 

[chemisttree]

Very difficult to test and maintain a seal against the skin with fabric masks of any design. Proper fitment, proper use yields proper protection.

 

[Mister Perfessor]

https://www.ncbi.nlm.nih.gov/pubmed/31479137
And this more recent one confirming no significant difference of laboratory-confirmed Influenza between the N95 and the paper Medical Mask.

Oops! A bunch of posts (10) disappeared while editing this. Oh well.

That's nice, but this thread was about DIY masks. And more specifically, asking about the levels of formaldehyde that might be found in commonly available materials such as Shop Tool brand paper towels sold by Harbor Freight

The particle size being stopped by shop towels is a subject of the general DIY discussion. This is more about 'everything else we forgot to consider', with formaldehyde being one of many possibilities

The Toronto study conducted after the SARS outbreak on masks & N95 respirators found that there was an issue with skin rashes due to direct skin contact for extended periods with a few of the professionally made masks. And their findings was that formaldehyde was the main culprit

I myself would simply put it as: 'Ok so it stops the virus, but is it also hypoallergenic?' Because as I see it, there are several good choices for filtering, but maybe only a few that I would want to actually wear!

Actually, what I am really interested in is a DIY version of a battery powered air filter for use with a face shield, not a mask. Powered systems have several advantages. No requirement for a good face seal, no skin contact with the filtering media, filter media can be a rigid fabric without issue, no overheating mask issues, no fogging up of eyewear, contaminated filter media is not mounted on your face and can be removed & replaced with a lot less direct contact with the media surface

 

[BillTre]

Actually, what I am really interested in is a DIY version of a battery powered air filter for use with a face shield, not a mask. Powered systems have several advantages. No requirement for a good face seal, no skin contact with the filtering media, filter media can be a rigid fabric without issue, no overheating mask issues, no fogging up of eyewear, contaminated filter media is not mounted on your face and can be removed & replaced with a lot less direct contact with the media surface

Sounds like you are talking about a system that provides filtered air to you under the sheild, which has all the advantages you describe.
However, it does not prevent you spreading any virus you might be sheding to others, one of the commonly cited goals of using face masks.

 

[Mister Perfessor]

Sounds like you are talking about a system that provides filtered air to you under the sheild, which has all the advantages you describe.
However, it does not prevent you spreading any virus you might be sheding to others, one of the commonly cited goals of using face masks.

I actually forgot that one little detail! Those last few replies sort of got me off track. Being that discussion of mask or respirator design isn't really the subject of this thread, I probably should have put that into a new post

But how this thread does apply to my PAPR project remains the same. A DIY filtering media that outgasses formaldehyde will still be a concern

 

[Keith_McClary]

I posted this on another thread. They recommend high-quality vacuum cleaner bags , but I can't see where they define that.

Flow analyses to validate SARS-CoV-2 protective masks

About distance rules, mouth-nose protection, particle filtering respiratory protection, filter materials and mask manufacturingChristian J. Kähler, Rainer Hain University of the Bundeswehr Munich Institute of Fluid Mechanics and Aerodynamics Werner-Heisenberg-Weg 39 85577 Neubiberg Germany

 

[Mister Perfessor]

I posted this on another thread. They recommend high-quality vacuum cleaner bags , but I can't see where they define that.

Flow analyses to validate SARS-CoV-2 protective masks

About distance rules, mouth-nose protection, particle filtering respiratory protection, filter materials and mask manufacturingChristian J. Kähler, Rainer Hain University of the Bundeswehr Munich Institute of Fluid Mechanics and Aerodynamics Werner-Heisenberg-Weg 39 85577 Neubiberg Germany

I like this paper, saving it for reference & sharing to anyone who cares

I am in the puget sound area, 33 miles from where the virus began inside the US. The local authorities have been advising DIY mask-makers to test their choice of fabric by running it quickly under cold water from a household faucet. If the water beads up and does not soak into the fabric until after a few seconds go by, then they say the fabric is ok to use

https://www.co.jefferson.wa.us/1450/VolunteerHow-to-Help - scroll down to "Community Face Mask Program"

That is an example of why there needs to be a better way to rate available materials. Basically, there's no official recommendation for a filtering material that actually works. Probably because of all the red tape involved. Suay Sew Shop at suayla.com, has been testing down to 0.02 micron with the meter they just bought. This paper does have an interesting choice of material, but I think it would be nice if that flow field testing could be done again with this material: https://www.ebay.com/itm/TOOL-BOX-S...318829&hash=item56d987a75d:g:7ksAAOSw409ej9Ae

Mainly because I was about to place an order for 4 rolls

That paper you linked to has a disclaimer from the company who makes the 'high-quality vacuum cleaner bag', see the bottom of page 21

 

[hmmm27]

(slightly serious)...

Why bother with a filter ? the NCV (especially attached to a sputum droplet) has pretty much the same natural diffusion speed as a brick, relying totally on air-currents to move around. Even a moderately ventilated area should be almost virus-free, up a metre or two.

Snorkel.

(Do draw a diagram and figure out airflow and capacities, before duct-taping this idea to your face)

(awaiting commentary from an actual scientist, of course. Efficacy decreases if everybody's doing it)