This is a wiki post for discussing creating and sourcing masks. Please add resources, information about sourcing supplies, requests for help, offers of help, or anything else that might be useful.
Hi Stew
It is recommended by the original designer. The material has close contact with your face/skin. Food grade plastics are generally certified to have very low levels of harmful chemicals.
My understanding is non-food grade plastics may leach harmful chemicals like plasticizers particularly during and after vacuum forming, some of which may be irritants or carcinogenic and so should be avoided for any kind of prolonged contact.
Did you know how to protect yourself from coronavirus. First stop touching your face. I know a very easy solution: just buy a mask. If you can’t find the mask in the shops, you can do it yourself. Here is a video of how to make a mask. Second thing what can you do wash your hands with soap
This type of mask also requires goggles and faceshield to be be used.
I’m starting a design using a full face snorkelling mask similar to Full face snorkel mask (Amazon, no referral)
The snorkel portion is detachable, and can be replaced with paper or multi-stage chemical system (micro salt looks interesting for a long life filter medium).
There is another mask on amazon which might be a better starting point Link but it is far more expensive. I consider it better in that the incoming air doesn’t pass your eyes and the design doesn’t require the one-way values used by the other system to control the air path.
Good morning from Perth - Jennifer
This sewing mask style can replace the filter. video If you cut the HEPA vacuum bags into filter size, they can be reused multiple times as long as the filter stay dry and without contact with the viruses. Make a few more sewing masks so you always have something dry to use. This style also applies for using surgical mask as filter.
Note: HEPA filter can filter 0.3 microns. It is an N95 equivalent standard. But, sewing mask can’t be perfectly sealed. It can’t be used as PPE.
HEPA Vacuum bags are a great call they still filter particles down to 0.3 microns which will catch most droplets but not free floating viral particles (aerosols of viral particles) so they provide partial protection. Droplets drying on the filter may also eventually release viral particles and so the filters need to be changed regularly.
With a sewn mask this may mean throwing the mask away as they may be difficult to sterilize.
Using a design that uses smaller pieces of disposable filter conserves scares filter material which is the idea behind the mask suggested by Moody.
Lets drill down into what makes a good respirator.
Challenges (a non-exhaustive list)
Good filter material is scarce / hard to make.
Filters become compromised / contaminated quickly
Other mask components (other than filters, i.e. valves) may also be in short supply
Strong filters impede airflow
They can be uncomfortable to wear
They require a good fit to the face
You need to protect your eyes
The respirator needs to be cleanable to reduce cross contamination
Based on the above, and assuming we can find the best filter we can get locally,
The best respirator will:
Reduce filter contamination, usually by having separate pathways for inhalation and exhalation. Inhalation though the filter, exhalation though a one-way valve
Use minimal amount of filter to achieve desired level of filtration
Have an exchangeable filter element independent of the rest of the mask
Have a reusable valve so that you don’t need to throw away the valves every time you change the filter
Have minimal impedance of airflow ( another reasons why respirators have valves)
Form a great seal with a wide range of face shapes ( this one is hard )
Incorporate eye protection or allow a separate eye protection to be worn
Not direct contaminated air towards the eyes
Have a body (excluding filter) made of an easily cleanable materials which can be disinfected multiple times
From the above you can see that use of a valve separates a respirator from a mask. Valves enable the concept of separate airflow’s for inhalation and exhalation which decrease filter contamination increase comfort and longevity over a simple mask.
Making cheap easy to produce one way valves for respirators is a good area for study. But beyond that have a think about all the challenges above and maybe share your thoughts on how to address them in comments below.
@Dee great summary.
With regard to face fit - this is why I started with diving system - they come in sizes and forming them to work well (water tight) on various face shapes is a know and pretty well engineered problem (double silicon seal).
As long as you can keep the one-way valves out of the line of fire so they don’t require disinfecting they can be common flappy valves (Any soft/compliant material. Leather has been used for centuries!).
Perhaps one of the design goals should also be the separation of inside (user contacting) with external (disinfectant friendly) framework and items. So for the full face system I’m playing with atm, you would want the seals and straps as a protected under-layer with a clip on/wear over layer designed for exposure to environment and survive repeated disinfecting. This would save the issue with cross contamination during removal (entire outer system removed as a unit, leaving inner protective layer in place).
Actually a few more for the features list…
Must accommodate glasses
Should have room for headset/headphones in protected volume. Possibly a sealing wire port or just assume bluetooth?
I can see that being advised to leave supplies of masks to those who need it. However given it’s such a long time between catching corona virus to displaying symptoms, having a mask for seemingly healthy people could help avoid spreading it. So while social isolation is key, we do need to go out to get food. Wearing masks then could help, so if home made ones do the job, i don’t see the harm. But yeah don’t go out and buy ones that medical professionals could use.
I was wondering if for example sprying alcohol at 70% could make home mask more efective for at less say 10 minutes (or something that could make travel in public transport more safe)… I guess is less, but I just where wondering.
I thought of soaking it on alcohol at 70º because is the thing that comes in gel… and also because when you put a clothe with water in your face it becomes “difficult” if soaked too much (also remember it in movies when people want to get “extra info”)… but it seems that there is a real solution more accurate that my imagination.
I add some extracts of the 2017 paper:
While vaccination can greatly reduce morbidity and mortality, during a pandemic or epidemic new vaccines matching the specific strain would be available, at the earliest, six months after the initial outbreak. Additionally, following development of an effective viral vaccine, several potential problems would remain, such as limited supply due to insufficient production capacity and time-consuming manufacturing processes. As a result, individuals close to the point of an outbreak would be in imminent danger of exposure to infectious diseases during the non-vaccine period. In the absence of vaccination, respirators and masks can be worn to prevent transmission of airborne pathogenic aerosols and control diseases, such as influenza.
Then it goes on
Therefore, a key challenge is the development of an easy-to-use, universal virus negation system, which is reusable without reprocessing and capable of deactivating pathogens, thereby reducing potential risk of secondary infection and transmission.
And “finish it” by
Here, we report a simple but efficient virus inactivation system exploiting the naturally occurring salt recrystallization. Our strategy is to modify the surface of the fibrous filtration layer within masks with a continuous salt film for virus deactivation via two successive processes: i) salt is locally dissolved by the viral aerosols and ii) supersaturation is followed by evaporation-induced salt recrystallization. Consequently, viruses are exposed to increasingly higher concentrations of saline solution during drying and physically damaged by recrystallization.
So yeah, a solution and that know about the shortages, a solution for the masses… not know and taked into account by goberments, WHO, ghsindex or any other… the world isnt prepared with real solutions that dont require lock down, because the other “solutions” are prettier than a do it yourself kit (maybe later I will delete this “politic part”).
more accurate that my imagination.