A simple way to reuse disposable face masks?

[newshound]

Actually RNA, but still a relatively fragile molecule with covalent bonds so it ought to heat up a bit. You might cook your elastic straps first though, or any thermoplastic bits.

[Paul]

But the medical people want everything a PPE could possibly come in touch with, to be cleaned off.

If you were working with a patient with drug-resistant TB, C.Difficile, and COVID-19, the cleaning procedure would have to cover those too. Whereas a home user, you would hope that drug-resistant TB isn't present. The TB thing is one thing I feared at our local hospital. And they bring people from remote areas, hundreds of miles to my hospital, so they can cough on us :-) Well, they gotta go somewhere... My hospital is pretty good about putting masks on people, where their range of conditions include the possibility of tuberculosis. The more trips I make to the hospital, the more I learn about weaknesses in the system.

That's another reason for the gamma ray thing. An attempt at total coverage.

It would be better to be making masks out of something "more permanent" that can take a healthy dose of gamma. That would be a kind of "end-to-end" design, rather than trying to retrofit a process to something intended to be disposable.

Paul

[Kelly]

Yes, definitely, if working or coming into contact with contagious hospital patients I would want the best PPE possible, the full kit. I am only messing about trying to re-use disposable masks to go shopping, down the supermarket, say. And we are not suppose to deprive our NHS front line workers of their stuff by buying up all the best face masks, even if we could get hold of them, not to mention afford them, that is.

I think I'm edging towards the compromise (until I get more supplies - as needed) of maybe re-using disposable face masks, say 2 or 3 times, by sterilising them in a pressure cooker. I'll review things as they go along, and hope to keep healthy all the while.

[polygonum_on_google]

We have home-made cotton masks (made to fit by partner). Obviously, we have no way of actually testing. But our choice is to steam iron them. Apparently (from some reasonably sensible sources) ten seconds full blast steam just might be enough to sterilise them adequately. Obviously, not thinking about the worst possible pathogens as we each have our own and no-one else will even touch them.

I think the odds are good enough that it will work.

[newshound]

One of the good things about chlorine is that it is readily detectable at a very low (and AFAIK safe) level.

IIRC it does not have the evil property of H2S where a relatively limited exposure winds down your sensitivity to it, so that it is not too difficult to end up breathing a toxic dose.

I'm happy to be corrected by someone "in the trade".

One of the things they taught us during fire extinguisher training is that if using CO2, at the point where you get the "lemonade" taste in your mouth then you get the hell out and leave it to the guys with B/A sets.

[Kelly]

I've also been considering making my own cotton masks after coming across this Cambridge Uni publication (the full-text PDF can be downloaded) which shows just how effective, for example, a doubled-up tea towel material face mask can be.

It sounds good to me too. I've picked-up so much valuable info today, and now I have a further option. Thanks for being so helpful.

[Kelly]

Okay, so I shouldn't totally rule out bleach at this stage then. It's almost impossible to get everyone in total agreement on certain things, sometimes you just have to trust your best judgement... I do get it right now and again. :)

[Roland Perry]

In message [e-mail]>, at 08:28:09 on Sat, 18 Apr 2020, Kelly [e-mail] remarked:

What's wrong with a simple pan of boiling water?

[Brian Gaff (Sofa 2]

Snigger.... However, its one thing to do such things, another to be sure its been done properly and indeed how many times you can do it. I had to laugh at an item on a local news bulletin late last week suggesting face masks would enable the opening of cafes and restaurants. Hang on how do you eat while wearing a mask then? Some people are pretty thick and are in charge of radio stations.

I personally loved the explanation of the joke somebody saw in a cartoon. Everyone at the off licence was queued up all wearing nylon stocking over their faces as makeshift mask as per You Tube, but two of them had crowbars and such in their hands and were at the front talking to the bloke behind the counter, we said its no good coming in here pretending to be crooks, I don't believe you. Brian

[Kelly]

Don't tell me that would suffice? All these do's and don'ts they come up with online - all sorts, as long, seemingly, as it's not too easy. Why don't they just say that? So, dip the mask in a saucepan of boiling water, say for what, 5-10 minutes, even squirt in a little washing up liquid for good measure - would that do it? That would be similar to laundering the mask at a very high temperature.

[Paul]

In a test of materials for making masks (by a company making masks), cotton Tshirts were the best compromise between arrestance (the difficulty of breathing through the solution), versus performance. While the vacuum cleaner bag filter achieved higher filtering performance, it was too hard to breathe through to make a good mask material.

The trick with making a mask, is fitting the face and not leaving a gap where all the air is really flowing. If I tied a bandanna across my face, and the material had any sort of arrestance, the air just flows through the gap between the mask and your nose.

I was wearing some mask six months ago (a hospital mask donned because the staff didn't know at that point whether I might have TB), and the metallic nose-piece, you just couldn't adjust the damn thing for an airtight fit. As soon as you stopped pressing on it, it would spring back a bit and bam, no seal. Once I'd had a biopsy and the test came back "no cancer, no TB", then on my next visit I didn't have to wear a mask. That just goes to show, that for purpose-built masks (not DIY ones), they still can't come up with a good/cheap solution for fit. For preventing me from coughing on people (droplets), it was a perfectly good solution - for preventing me from catching stuff from someone else, not so much.

Paul

[Kelly]

Go ahead and have a laugh, why not?

I don't imagine too many people are under too many illusions over the limitations in what they are doing. Just making a little effort to protect yourself a little better, as best you can until you can do yet better again, seems worthwhile to me. I appreciate not everyone thinks the same way.

[Paul]

Here's a recent article.

"Disinfectants are effective against coronaviruses

It's true that disinfectants effectively kill coronaviruses.

Coronaviruses are enveloped viruses, which means they are protected by an "envelope" made of lipids or grease that is easily dissolved by cleaners and leaves the virus itself vulnerable.

"This means they are one of the easiest types of viruses to kill with the appropriate disinfectant when used according to the label directions," says Health Canada.

It recommends cleaning high-touch surfaces such as door handles and phones with either:

Regular household cleaners. Diluted bleach (one part bleach to 50 parts water).

It has also published a list of disinfectants that are likely to be effective against COVID-19 on hard surfaces. "

The tone of the article, makes it sound easy, but you have to be careful as to how you interpret that. What is a regular household cleaner ??? At least the sentence about bleach gives some idea about the kind of strength they have in mind. The bleach I've got, I wouldn't use that on a mask, as the smell wouldn't go away.

I think I have only one bar soap here, that would make an acceptable cleaner, as you can rinse it away when you're done. After thorough drying, the smell would almost be gone.

COVID is not supposed to survive as nicely on cloth as on hard surfaces. Stainless steel for example, is one of the worst surfaces, in that it encourages the COVID to survive. A stainless steel door knob then, would be a bad item, and would be a cleaning target.

Paul

[alan_m]

Or just hanging it outside on a washing line (dry) and let the airflow and UV do the job.

Buy a ozone generator and use it in a sealed plastic box with the mask.

[alan_m]

Why boiling water with detergent. You don't wash your hands in boiling water!

[Roland Perry]

Why wouldn't it?

Which is what nurses have to do with their uniforms since time immemorial. It's even got a name "a boil wash" (albeit 90 degrees rather than 100)

[The Natural Philosopher]

washing hands is designed to rid the hands of surface contamination Boiling is designed to kill in situ shit in the fabric pores

since we cant actually boil hands we use sanitiser gel instead

[Kelly]

I've had to change my views, over the last day really, on a many aspects of face masks as so many new opinions and facts have been brought to my attention. Bleach, for example, I can see why online you would often be told not to use that to serialise face masks. But, as you point out, the strength of any bleach needs to be taken into account to ensure relative safely of use, and because of the weakest link (i.e. someone who would just use any bleach straight out of the bottle) it's more responsible to simple tell us all: 'Don't use bleach'. Yet if you can get the strength right and you're not left with a mask full of bleach fumes, who knows?

Yes, there is a lot to consider. You can't know too much but I suppose the trick is to at least know enough.

[Kelly]

True, it is as you say. And I am confident this will suffice for the cotton masks I'm going to make. (A filter layer element, which I'll be able to slip in and out of the mask, I'm going to consider as being replaceable.) So, I no longer see any problem there.

[Chris Hogg]

A potential problem with your removable/replaceable filter: if the filter element has significant 'arrestance', then when you inhale, the air will bypass the filter and just go round the edges through the cotton. You'll have to be a bit clever with the design to prevent that.