Facemasks from old HF dust collector bags

[Cdshakes]

so i keep seeing people make face masks from bandanas, t-shirts, even papertowels...etc.

Would the original bags that come with a Harbor freight dust collector be better than these materials (since n95 masks are hard to come by these days and should be reserved for those in the medical profession)
What do you think?  Should i cut mine up?  I never used them even... so no dust on them...

Colin

[mound]

so i keep seeing people make face masks from bandanas, t-shirts, even papertowels...etc.

Would the original bags that come with a Harbor freight dust collector be better than these materials (since n95 masks are hard to come by these days and should be reserved for those in the medical profession)
What do you think?  Should i cut mine up?  I never used them even... so no dust on them...

Colin

I'm no scientist, but I do deal with microscopy and the world of small things. As I understand it, most water droplets carrying a virus are less than 5 microns in size. The HF dust bag is a 5micron filter. So I would assume that it would not protect you. When I hear "use a scarf of t-shirt it's better than nothing" type comments, I wonder the same thing.. If your filter isn't going to stop droplets smaller than 5micron from getting through, how is it valuable at all other than to make you feel like you're doing something rather than nothing?

[Cdshakes]

with the scarf/t-shirt method, i keep hearing it's not to protect, but rather to prevent you from spreading, if you were infected and didn't know it.  Not sure how that works exactly...

[mound]

with the scarf/t-shirt method, i keep hearing it's not to protect, but rather to prevent you from spreading, if you were infected and didn't know it.  Not sure how that works exactly...

Same problem though.. If I cough behind some fabric that has holes larger than 5micron, it's not likely to stop anything, it'll pass right through it. (I suppose it may filter out some of your nasties if they embed on the fabric, but most would presumably pass right through it)

[Cdshakes]

Same problem though.. If I cough behind some fabric that has holes larger than 5micron, it's not likely to stop anything, it'll pass right through it. (I suppose it may filter out some of your nasties if they embed on the fabric, but most would presumably pass right through it)

wonder how small a t-shirt or scarf will filter down to...?

[Rob Young]

wonder how small a t-shirt or scarf will filter down to...?

About the size of pollen. 

Interesting read and some size comparisons.  Essentially they normalized the measurements against surgical masks (not sure which ones though).

https://smartairfilters.com/en/blog/best...ask-virus/

Very difficult to breath through filter materials. Easier through things like t-shirts, dishtowels.

[MichaelMouse]

I'm no scientist, but I do deal with microscopy and the world of small things. As I understand it, most water droplets carrying a virus are less than 5 microns in size. The HF dust bag is a 5micron filter. So I would assume that it would not protect you. When I hear "use a scarf of t-shirt it's better than nothing" type comments, I wonder the same thing.. If your filter isn't going to stop droplets smaller than 5micron from getting through, how is it valuable at all other than to make you feel like you're doing something rather than nothing?

Simple.  It's not a filter, it's a barrier.  Chances of some airborne snot hitting a hole square on are infinitesimal compared to hitting a thread.  Since they're damp, a glancing hit will stick in those even tinier hairy edges you see under your microscope on each thread.  

I've tried over and over to remind people that, similarly, "dust" masks aren't filters, but barriers.  The speck not only has to hit the hole, but be drawn through at an extremely small pressure differential.  Really low chances.  Better than nothing?  Much better, but if they were sieves, they'd fill with particles until they took your breath away.

Reminder - a second, or third layer makes it even more likely the mask will stop any pass-through. That's why commercial masks use felted construction rather than single layer.

[jteneyck]

I read that report in the link a week or so ago.  Since a vacuum cleaner bag had the best filtration below a surgical mask I went and got one of the 3M Filtrete bags our Miele vacuum uses, cut it up, and fashioned a mask out of it to see how difficult it is to breathe through.  Turns out, at least for me who has no difficulty breathing, it's easy. I actually used it today when I picked up a prescription at the grocery store.   This was the first time I've been in a store in over a week, and I was surprised how many people were wearing masks.  I was especially surprised that most of the masks I saw were commercially made, not N95's but still what looked to be higher end than the really cheap ones.  Where are people buying them?   

John

[mound]

Simple.  It's not a filter, it's a barrier.  Chances of some airborne snot hitting a hole square on are infinitesimal compared to hitting a thread.  Since they're damp, a glancing hit will stick in those even tinier hairy edges you see under your microscope on each thread.  

I've tried over and over to remind people that, similarly, "dust" masks aren't filters, but barriers.  The speck not only has to hit the hole, but be drawn through at an extremely small pressure differential.  Really low chances.  Better than nothing?  Much better, but if they were sieves, they'd fill with particles until they took your breath away.

Reminder - a second, or third layer makes it even more likely the mask will stop any pass-through. That's why commercial masks use felted construction rather than single layer.

great points!

[AHill]

Same problem though.. If I cough behind some fabric that has holes larger than 5micron, it's not likely to stop anything, it'll pass right through it. (I suppose it may filter out some of your nasties if they embed on the fabric, but most would presumably pass right through it)

Most will be blocked by the fabric.  Only a very small percentage passes through.  It's like light coming through a screen.  Not all of it makes it through the screen.  But yes, some of it does get passed through the open holes of the fabric.