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Can we produce a face mask (i.e. *not* the eye protection visor) #17

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ajlennon opened this issue Mar 28, 2020 · 43 comments
Open

Can we produce a face mask (i.e. *not* the eye protection visor) #17

ajlennon opened this issue Mar 28, 2020 · 43 comments
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designs - masks medical_input

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@ajlennon
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ajlennon commented Mar 28, 2020 •
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It feels like most people involved in the PPE effort have concentrated on what we have been told by medical professionals should be called "eye protectors" i.e. the face visors we are designing and printing / laser cutting / etc.

I suspect this is because we don't know if we could provide a filtering face mask that would be useful to medical professionals and those in the community and we don't want to be producing useless items that are of no real benefit.

There seems to be a lot of confusion around this issue so I am hoping we can come to some science backed conclusions as to whether we can do something, or whether we should leave this alone.

There has been discussion on Twitter - I think on @realsexycyborg's threads - that a lot of 3D printed face masks are useless. A big problem seems to be they don't properly fit to the face.

More recently I read this article which is saying the the following

A study from City University of Hong Kong found that the efficacy of a mask made at home out of two pieces of paper towel + a tissue “…were proven to have achieved 80 to 90 per cent of the function of regular surgical masks in terms of their filtration of aerosol and droplets.” That’s pretty good for something you can make from home.

https://medium.com/@thejanellemj/please-join-me-in-wearing-a-mask-71e0e3f4fe4a

@AlyssaAlabassi (Surgeon) provided this link to an opensource printable mask on Twitter

https://www.futura-sciences.com/tech/breves/imprimante-3d-coronavirus-masque-n95-impression-3d-2211/#xtor%3DRSS-8

ref thread: https://twitter.com/AlyssaAlabassi/status/1243956886329843713?s=20

She also provided this link from the Lancet on use of masks

"Rational use of face masks in the COVID-19 pandemic"

https://www.thelancet.com/action/showPdf?pii=S2213-2600%2820%2930134-X
@ajlennon
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ajlennon commented Mar 28, 2020 •
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Slightly off-topic but there is also this link on cleaning N95 masks

"Duke University uses vaporized hydrogen peroxide to clean N95 face masks for reuse"

https://twitter.com/evankirstel/status/1243957616914685953

More on this (Sorry, it's the Mail, I know but...)

https://www.dailymail.co.uk/news/article-8162525/Duke-University-researchers-develop-method-contaminate-worn-N95-masks.html

@amcewen amcewen mentioned this issue Mar 28, 2020
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@ajlennon
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@markmellors commented on Twitter in relation to the "Futura Sciences" mask that

this face mask design is snake oil. I've tweeted replies to a few people about it, as have many leading 3d printer experts. in short: poor sealing, high filter pressure drop, no proof of reuse. worse than a cloth mask

ref: https://twitter.com/MarkMellors/status/1243963421546201089?s=20

@ajlennon
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The pinned tweet at the top of @realsexycyborg 's timeline has this to say

Why not 3D Printed masks:
https://twitter.com/RealSexyCyborg/status/1240737164654047232
Why cloth masks for the public and N95 for Health Care Workers:

ref: https://twitter.com/RealSexyCyborg/status/1241611801390874624?s=20

@ajlennon
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@JackiePease sorry to duplicate your issue. Looking at what @realsexycyborg is saying can we reach out to the fabric / sewing community for advice and help?

@markmellors
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markmellors commented Mar 28, 2020 •
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To avoid duplication, I've reviewed a bunch of designs for various challenges here:

https://docs.google.com/spreadsheets/d/1IpP0RV0dE5zKPK88EAz2shHbk8pkFB0kyJwnrUkHyUg/edit?usp=sharing

which highlights the issues and the ones I think are best at this time.

I'm currently trying to concentrate my efforts on teh visors, as I know we can produce something that meets the required standards. I spent a week looking at filtering masks and couldn't come up with anything better than a sewn cotton surgical style mask.

Key constraints:

  • filtering efficiency. primary driver is catching droplets. if it can filter virus great, but actually not essential. HEPA filters meet approxiamtely same spec as N95.
  • fit. must seal well to the face. more important than filtration as anythin that leaks aroudn the side is clearly not beign filtered. this includes fitting whilst talking. a 3d printed mask won't do this. must be soft.
  • pressure drop. small filters make it hard to breath and increase leaks. both a health issue. this is why pleats are good.
  • supply chains. almost all good filters are made with melt blown PP, as far as I can tell. There is a global shortage of this material. Any hacked solutions that puts load on that supply chain is taking it away from actual ffp3 or similar masks, which would be a better solution. cutting up perfectly good masks is a very bad solution. see pressure drop.
  • reuse and sterilisation. current masks are disposable. if significant effort is put into a mask it needs to be reusable. cotton masks can be hot washed, which is an efficient way to sterilise them. 3d prints cannot (pores, temp sensitivity, hospital proceses). There is some research that suggests n95 style masks can be sterilised in a warm oven. IMHO this is a much better solution than any DIY mask will be. heling this be practical in a hospital may have a better return on effort. As with all this, you'll need a contact on the inside to explain their constraints. I haven't found one yet.

ajlennon added a commit that referenced this issue Mar 28, 2020
@ajlennon
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@ajlennon
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ajlennon commented Mar 28, 2020 •
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I had this feedback from Alyssa Alabassi (Surgeon)

To return to the article you sent me and the question attached to it. Yes, opinions are divided regarding the usage of masks in the general population. However the initial slogan in the campaign referred to tissue usage rather than cloth handkerchiefs. People are more likely to forget to wash a cloth mask than to bin a tissue one. Cloth masks can easily become an infection portal, so no to cloth masks. Personally, I think people should wear basic tissue masks (not N95masks) to reduce droplet splatter from themselves and to avoid getting splatter from others. There are a lot of people who have no symptoms but carry the disease so impossible to know who's infected and who's not! It also reduces people's tendency to touch their faces which increases infection risk.

It's a personal opinion but based on what's been written so far and related facts. Absolutely, what the general public can use and what the NHS should use are different but unfortunately, even in the NHS, many nurses and doctors aren't using basic tissue masks in an outpatient setup. Neither are GPs, which increases their likelihood of catching the virus from someone with no symptoms and either getting infected themselves or passing on to others.

In a basic clinical setting, such as outpatient departments and GP surgeries (not seeing covid patients), even pharmacists and other public interfacing services, a face shield (transparent and allows easier communication) is better than nothing at all and reduces splatter related infection risk.

The comments on face shields in the wider community also relate to issues #6, #9

As you can see, the guidance is for contact with Covid confirmed cases and those performing intervention on Covid patients. General nursing and medical staff are not included. With such a contagious virus and the fact that many don't display symptoms, an extra layer of protection needs to be considered

@ajlennon
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Resources here from @SayBeano

How to sew emergency masks

https://youtube.com/watch?v=L55CNVm2FXw

https://m.facebook.com/masks4medicine/

@ajlennon
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This feedback from "The Purple Stitcher" @Madscouser

There's lots of different mask patterns out there, my 1st suggestion would be getting a medical person to advise which would be best. This one has a waterproof barrier in the middle, which seems a good idea to me but I'm not medical, so not sure!
https://m.facebook.com/story.php?story_fbid=10163087817675562&id=756880561

@ajlennon ajlennon mentioned this issue Mar 29, 2020
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@JackiePease
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JackiePease commented Mar 29, 2020 •
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I DMd Cathy about this as well. Her response is also that we need to be sure of what we're doing, but seems happy to help:
"Yes that sounds good as long as we would be adhering to the regulations, I have calico here but not sure if there's regs on which fabrics to use, I've also got bits of cotton fabrics in colours and prints
The only thing is i only have aboit 4.5 metres of thin elastic so that wouldnt get me very far. Could anyone provide the elastic and materials?"

@ajlennon
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Maybe we should add a face mask consumables section into - #21 ?

@amcewen
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amcewen commented Mar 29, 2020

Dunno, getting some medical input on a design seems more useful first? Maybe @afroleft can see if any of the medical people he's been talking to have any opinions on masks?

@ajlennon
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Agreed - but as with the 3D Printing and Laser Cutting I am guessing there are some consumables we know we will need even though we're not sure of the designs.

@epsaul
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epsaul commented Mar 29, 2020

I'm not an authority but you can buy HEPA filter vacuum cleaner bags which may (or may not?) be a suitable material specification for viruses. There is also a duckbill pattern on the internet and people are making these in fabric. This is reportedly a good fit but I think if you used the hoover bags (HEPA spec) for the fabric this would maybe be a way to go.

@JackiePease
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JackiePease commented Mar 29, 2020 via email

@ajlennon
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Gotcha - OK

@ajlennon
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Information on mask designs via @SayBeano

https://m.facebook.com/story.php?story_fbid=2962276270503347&id=403061379758195

@TheSmallLebowski
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I'm in no way an expert and I'm coming from a dressmaking background not a scientific one, but from what I can find online it seems a non woven material is what's needed. The medical masks are made from a type of polypropylene. I have sourced 20 metres of this and plan to make some to give out, possibly to homecare agencies who go into the houses of the most vulnerable and seem to be in woeful short supply of masks.

Other thoughts I had were maybe using a cotton but ironing a light/medium interfacing to it before cutting... I think interfacing would be appropriate as I believe it is also non woven but I need to research that more to be certain.

I thought they would at least be useful to people who are going out shopping for other vulnerable friends and family, just to minimize risk if they couldn't be used in a medical capacity.

@TheSmallLebowski
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I'm not an authority but you can buy HEPA filter vacuum cleaner bags which may (or may not?) be a suitable material specification for viruses. There is also a duckbill pattern on the internet and people are making these in fabric. This is reportedly a good fit but I think if you used the hoover bags (HEPA spec) for the fabric this would maybe be a way to go.

Apparently these are one of the best in terms of filtering, but not easy to breathe in 🤷🏼‍♀️

@JackiePease
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Comment from @KayaScott via email (she's currently having difficulty commenting on GitHub):
"I would like to get involved on the textile side of things... I can offer time and stitching...
I have recently seen this video from a Dr Ryan Southworth, Emergency Dr in the US and his wife, about making the duck bill facemask with hepa filter vaccuum bags... https://m.youtube.com/watch?feature=youtu.be&v=W6d3twpHwis
For use in hospital..

Re sterilising:
Hairdressers should have autoclaves for sterilising equipment, nail and Beauty salons, tattoo and piercing studios should, and I think dentists...
Could be worth checking out how suitable this method would be. I am sure if suitable a call out to get hold of a couple to ensure all fabric masks are sterile before distributing? Not sure if they would be suitable for the visors though.

While trying to find out about suitability of autoclaving for sterilising the fabric masks I came across an article which talks about making masks from the fabric surgical instruments are wrapped in when being sterilised (brand name Halyard H600) https://www.healthcarepackaging.com/home/article/21124863/second-life-sterile-wrap-fashioned-into-masks."

@SayBeano
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I'll reach out to tattooists today to see if any are prepared to to loan autoclaves should they be needed

@JackiePease
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I've given @Madscouser and @KayaScott details to Cathy, as she and Mary are separately organising sewing of scrubs and hopefully masks too:

https://m.facebook.com/story.php?story_fbid=10221412229284946&id=1526123237

It would still be good if we could use NHS contacts to find out what kind of masks are useful - Mary believes they need to be disposable

I told Cathy that we could probably find other sewers by publicising on @DoESLiverpool social media

@JackiePease JackiePease mentioned this issue Mar 31, 2020
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@amcewen
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amcewen commented Mar 31, 2020

@JackiePease Ace! @afroleft is probably best places for finding things out from NHS contacts. I'll aim to ask when I'm talking to any too though - the local procurement guy I spoke to earlier did say they were currently using masks that were 4 years out of date, and they have been re-using other PPE that's supposed to be single-use, but that'll be easier with something like a visor...

@huffeec
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huffeec commented Mar 31, 2020

@JackiePease Helen has been to collect one of our sewing machines to help out with this. We're thinking that even if there isn't a clinical use there will be community channels that could distribute them for individuals to use. Will keep a watch on this thread for any updates on a preferred design/materials.

@helenpstephens
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Hi there. Been testing out a couple of designs from online tutorials to see which are easiest, quickest to make, comfortable to wear etc.
A lot of suggestions are to mske masks with a pocket to insert a filter material inbetween which can be changed regularly throughout the day. Filters can be made easily from dried out wet tissue/toilet roll (depending on how easy it is to get hold of these days). Both main styles (pleated and wjatever the other style is called) have designs that include a pocket layer.
The walton centre has just put a call out for masks for healthcare workers, I'll respomd and see what they advise.

@ajlennon
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ajlennon commented Apr 2, 2020

@helenpstephens feels like it would be good to get feedback from somebody who knows about whether this is true

image

ref: https://medium.com/@thejanellemj/please-join-me-in-wearing-a-mask-71e0e3f4fe4a

@JackiePease
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Great - @helenpstephens - would you like me to put you in touch with Mary and Cathy who are looking into this?
Also, is that a sewing machine from Sandbox or DoES Liverpool, and which one?

@helenpstephens
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That'd be great @JackiePease.
The sewing machine is from Sandbox. It's a Viking. I'm still getting used to it.

@helenpstephens
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Quick update: Walton Centre has a strategy meeting tomorrow and they're going to discuss their needs and what sort of specs we need to work to, if fabric masks will be of any use to some of their staff. I'll report back tomorrow when I hear more.

@KayaScott
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Breaking my heart, net's lot just think about the NHS...this is a message from a friend of mine who has previously had a heart attack, is recovering from breast cancer, should herself be at risk and isolating, caring for a Mum with Alzheimers.....
My Mum and Dad been on lockdown for over a month.
My brother heard disturbing things from a consultant and rang me .
We told them to isolate and they have .
Me or Steven do their shopping and leave on step they look amazing and don’t seem phased .
Iam in a nursing home doing behavioural observations for continuing health care .
It’s a clinical nursing unit so a strict infection control regime .
Temp taken on arrival and form everyday .
No cases so far.
The thing is we may be running out of protective stuff soon as it’s all going to the hospitals but they are trying to force care homes to take in covid19 cases too .
They are not taking anyone over 65 into hosp .
It’s really scary and going to get worse.
Was thinking maybe you could make some aprons or poncho type covering ours our so flimsy.
Face screens too
I have goggles but most staff have none x
Working 6 days a week we have no staff .

off but he is getting his pay they had to close his where he works .

It not good just hope and pray they can come up with a vaccine x

@tamhamilton
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I'm in no way an expert and I'm coming from a dressmaking background not a scientific one, but from what I can find online it seems a non woven material is what's needed. The medical masks are made from a type of polypropylene. I have sourced 20 metres of this and plan to make some to give out, possibly to homecare agencies who go into the houses of the most vulnerable and seem to be in woeful short supply of masks.

Other thoughts I had were maybe using a cotton but ironing a light/medium interfacing to it before cutting... I think interfacing would be appropriate as I believe it is also non woven but I need to research that more to be certain.

I thought they would at least be useful to people who are going out shopping for other vulnerable friends and family, just to minimize risk if they couldn't be used in a medical capacity.

Can you link to the material you found, and your source, please? Thanks in advance

@TheSmallLebowski
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I'm in no way an expert and I'm coming from a dressmaking background not a scientific one, but from what I can find online it seems a non woven material is what's needed. The medical masks are made from a type of polypropylene. I have sourced 20 metres of this and plan to make some to give out, possibly to homecare agencies who go into the houses of the most vulnerable and seem to be in woeful short supply of masks.
Other thoughts I had were maybe using a cotton but ironing a light/medium interfacing to it before cutting... I think interfacing would be appropriate as I believe it is also non woven but I need to research that more to be certain.
I thought they would at least be useful to people who are going out shopping for other vulnerable friends and family, just to minimize risk if they couldn't be used in a medical capacity.

Can you link to the material you found, and your source, please? Thanks in advance

https://www.ebay.co.uk/itm/353019923652

Still waiting for it to arrive but it's coming Royal Mail and I think they are very pushed at the minute. It was due to arrive on the 4th. I can update on suitability when it does finally get here, really hoping that's today!

@tamhamilton
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Thanks for the link!

I just did a bit of reading into this, and found the following...
The material correct to the N95 spec is generally called 'N95 nonwoven (or melt-blown) polypropylene'. It is also known as BFE 99 (>99% Bacterial Filtration Efficiency). There are also N99 and N100 fabrics which exceed the N95 spec. P2 and P3 filters are equivalent to N95 and N99 respectively, as are FFP2 and FFP3.

Nose wires are generally ~0.6mm galvanised iron (that's a paperclip to you and me!), or ~0.5mm stainless steel (thin MIG welding wire might work), or 0.5-0.8 x 3-5mm soft (annealed) aluminium strip.

To comply with N95 spec, the finished mask must also achieve <8% inward leakage. N99 spec requires <2%. Of course this is probably impossible for us to measure, but it gives a decent indicator of how snug the fit of the mask needs to be. Surgical style masks generally offer about 60% filtration efficiency (compared with 95% efficiency of the N95), so I'd guess they're achieving around 30% inward leakage.... So nose wires really do make a huge difference!

Just in case anyone was unsure, N95 is the minimum spec which seems to be universally recommended as being decently effective against Covid. Other masks are probably better than nothing, if used/worn/sterilised/disposed of properly, but N95 is what we should be aiming to produce.

I hope that's helpful!

@TheSmallLebowski
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Yes very helpful thanks, I have found it all a bit confusing! So mine is meltblown, which is good. But couldn't find any when searching that actually said n95 that was actually available..
My plan for mine is to make them for home care workers/key workers as I know they are not really being thought of or have been allocated a woefully short supply.

I'm still looking for a reusable solution though, not sure if polypropylene or any non woven stands up to a 60° wash.

Must say this is all a bit of a baptism of fire, I'm much more used to making underwear, housewear type things that I want to be breathable 🤷🏼‍♀️

@TheSmallLebowski
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Oh also, I am wondering whether rolls of aluminium/stainless steel wire strip for nose covering could be bought on a roll from Screwfix/tool station or other hardware store still operating as a click and collect. I'm trying to limit my online orders now as post service completely under pressure now.

@helenpstephens
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I started making mine really just for people generally, to give them a bit of added protection when they go shopping. Although since I started, I got requests from pharmacy staff and foodbank volunteers.
I've just focused on a 2 layer cotton design on the basis that some protection is better than nothing and no one on the frontline, working with sick people will be using them. But getting people to keep them on when they're not used to wearing them means they do need to be comfortable and breathable.
I made some with ear elastic, I made some shaped and some pleated. I found pleated ones pressed my nose down and felt uncomfortable, the shaped ones are much better. Ear elastic hurt my ears and always felt like they would ping off, so i used elastic to go round the head instead which feels much more comfortable, shorter on the bottom to fit snug around the neck. The design can be made so the inner layer is a pocket for air filter material.
My hope is that if people use these, then it means the medical grade protection can be saved for the medical staff that really need it. I can't make anything in sufficient numbers to help the NHS but can help smaller local groups of people who won't get any protection offered, but are still coming into regular contact with people.

@markmellors
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Oh also, I am wondering whether rolls of aluminium/stainless steel wire strip for nose covering could be bought on a roll from Screwfix/tool station or other hardware store still operating as a click and collect. I'm trying to limit my online orders now as post service completely under pressure now.

I used a small piece of rolled up kitchen foil in mine. seems to work ok. slightly springier steel may be better, but I think its as good as buying aluminium strip, and easy and adjustable stiffness.

@JackiePease
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This article from The Guardian seems interesting re. use of DIY masks - there's a section on "Using and Taking Care of Your Mask" with guidance on when they should be used, how to take them off etc.
https://www.theguardian.com/us-news/2020/apr/06/how-to-make-no-sew-face-mask-coronavirus

@KayaScott
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KayaScott commented Apr 7, 2020 via email

@tamhamilton
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Apparently 75deg C is the minimum temperature proven to kill Covid-19. Below that temperature you're relying on soap/detergent/alcohol/etc to kill it.

Polypropylene should be OK up to about 100deg C, I think. It has a melting point of 130deg C. That will definitely require some testing though (pour boiling water over it, see what happens).

This might work for the nose wires:
https://www.toolstation.com/mig-welding-wire/p18355
It's not galvanised or stainless, so probably not very useful for reusable masks or sterilising.

Something like this may be better, but it really needs to be tested to find what works well:
https://www.amazon.co.uk/Stainless-Steel-24AWG-0-50mm-Extra/dp/B01BFI3HJQ/ref=sr_1_2?dchild=1&keywords=0.5mm+annealed+stainless+wire&qid=1586263182&s=diy&sr=1-2

@TheSmallLebowski
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Thank you everyone, some really helpful suggestions there.

@ajlennon
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ajlennon commented Apr 8, 2020

Feedback from Helpful Engineering that there's a cloth face masks project channel here worth looking at

https://helpfulengineering.slack.com/archives/CUYPTH7ED

@tamhamilton
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Can't sign up to their slack right now - the invite linked on their Twitter has expired... Am I missing something, or doing something wrong?

@ajlennon
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ajlennon commented Apr 8, 2020

Try this @tamhamilton

https://join.slack.com/t/helpfulengineering/shared_invite/zt-d9imalxu-~ZtKTdSq2bC8kTt2vcVVIw

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