# Masks to keep out the bad while letting in the good for pennies **URL:** \ **Category:** The Quarantine Zone\ **Tags:** covid-quarantine\ **Created:** [November 12, 2020, 8:57pm UTC](https://boards.straightdope.com/t/masks-to-keep-out-the-bad-while-letting-in-the-good-for-pennies/925462 "2020-11-12T20:57:45Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![rboyce](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rboyce/32/4066_2.png) [@rboyce](https://boards.straightdope.com/u/rboyce)\ **Post date:** [November 12, 2020, 8:57pm UTC](https://boards.straightdope.com/t/masks-to-keep-out-the-bad-while-letting-in-the-good-for-pennies/925462/1 "2020-11-12T20:57:45Z")
**Masks to keep out the bad while letting in the good for pennies** I have discovered that you can breathe through a coffee pot filter If you take four (4) coffee pot filters stacked one on the other, you can breathe threw them with no difficulty. **Coffee filters are inexpensive, and you can find them anywhere** There is one drawback. I need to find a way to hold the filters against my face. **Once done my masks problems will be over** What say you---- through away your filter mask on a daily basses and replace with a fresh one ps: you don’t need to wear a mask while driving in a car or sitting in a chair on your front yard (:- ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [November 12, 2020, 10:58pm UTC](https://boards.straightdope.com/t/masks-to-keep-out-the-bad-while-letting-in-the-good-for-pennies/925462/2 "2020-11-12T22:58:03Z")
At this point, you can find surgical masks just about anywhere. Start with Amazon, if you are so inclined. Coffee filters might have been a thing back in March, but they’re not really necessary at this point. ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [November 12, 2020, 11:05pm UTC](https://boards.straightdope.com/t/masks-to-keep-out-the-bad-while-letting-in-the-good-for-pennies/925462/3 "2020-11-12T23:05:10Z")
P.S. As always, though, any mask is better than no mask. ---
**Author:** ![Acierocolotl](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/acierocolotl/32/6241_2.png) [@Acierocolotl](https://boards.straightdope.com/u/Acierocolotl)\ **Post date:** [November 13, 2020, 3:48pm UTC](https://boards.straightdope.com/t/masks-to-keep-out-the-bad-while-letting-in-the-good-for-pennies/925462/4 "2020-11-13T15:48:59Z")
So a bit of proper science has been done on various common homebrew mask replacements. You may be surprised to see how poorly coffee filters rate. > **[Filtration performances of non-medical materials as candidates for...](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7373391/)** > > The recent outbreak of the coronavirus disease (COVID-19) is causing a shortage of personal protective equipment (PPE) in different countries around the world. Because the coronavirus can transmit through droplets and aerosols, facemasks and N95... If you just want a few numbers, scroll down to Table 1. They considered not only the ability of the masks to filter particles, but also the pressure drop through the mask (which affects how breathable it is). Coffee filters were bad at stopping particles, and had a large pressure drop as well, which meant they weren’t breathable and weren’t really stopping particles as well as other options. ---
**Author:** ![needscoffee](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/needscoffee/32/1076_2.png) [@needscoffee](https://boards.straightdope.com/u/needscoffee)\ **Post date:** [November 13, 2020, 4:47pm UTC](https://boards.straightdope.com/t/masks-to-keep-out-the-bad-while-letting-in-the-good-for-pennies/925462/5 "2020-11-13T16:47:18Z")
He mentions in a different thread that he hasn’t actually figured out how to attach the filters to his face. Seems like a bad idea all around when masks are ubiquitous now. ---
**Author:** ![rboyce](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rboyce/32/4066_2.png) [@rboyce](https://boards.straightdope.com/u/rboyce)\ **Post date:** [November 15, 2020, 2:25am UTC](https://boards.straightdope.com/t/masks-to-keep-out-the-bad-while-letting-in-the-good-for-pennies/925462/6 "2020-11-15T02:25:06Z")
> [@Acierocolotl](#): > > Coffee filters were bad at stopping particles, and had a large pressure drop as well, which meant they weren’t breathable and weren’t really stopping particles as well as other options. I searched “coffee filter” in that article and came up blank just saying ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [November 15, 2020, 3:10am UTC](https://boards.straightdope.com/t/masks-to-keep-out-the-bad-while-letting-in-the-good-for-pennies/925462/7 "2020-11-15T03:10:58Z")
> [@rboyce](#): > > I searched “coffee filter” in that article and came up blank > just saying Well, I just searched the article, and found ten matches for “coffee filter.” Here is a relevant quote from the article: > [@](#): > > Coffee filters provide moderate filtration efficiencies of around 50% for 0.3 μm particles, but the pressure drop is significantly higher than most of the other materials. ---
**Author:** ![rboyce](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rboyce/32/4066_2.png) [@rboyce](https://boards.straightdope.com/u/rboyce)\ **Post date:** [November 15, 2020, 3:14am UTC](https://boards.straightdope.com/t/masks-to-keep-out-the-bad-while-letting-in-the-good-for-pennies/925462/8 "2020-11-15T03:14:21Z")
> [@robby](#): > > Coffee filters provide moderate filtration efficiencies of around 50% for 0.3 μm particles, Then using two (2) filters gives you 100% protection and three (3) filters gives you 150% protection. if my numbers are right; which they are ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [November 15, 2020, 3:38am UTC](https://boards.straightdope.com/t/masks-to-keep-out-the-bad-while-letting-in-the-good-for-pennies/925462/9 "2020-11-15T03:38:05Z")
> [@rboyce](#): > > > [@robby](#): > > > > Coffee filters provide moderate filtration efficiencies of around 50% for 0.3 μm particles, > > Then using two (2) filters gives you 100% protection and three (3) filters gives you 150% protection. > if my numbers are right; which they are First off, that’s not how filters (or math) work. What exactly does 150% protection even mean? 🤨 Secondly, what also increases with adding additional coffee filters is the pressure drop, which translates into the difficulty of breathing through them. In all seriousness, why not just get a surgical mask? They’re cheap and readily available, and use meltblown nonwoven polypropylene fibers, just like N95 masks. This type of filter fabric has the best trade off between filtration performance and breathability (pressure drop). The only reason to use other materials, especially household materials like coffee filters, is if there is no other alternative. That may been the case back in March during the beginning of pandemic, but is no longer the case now. With all that said, I will say again that any mask is better than no mask. ---
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [November 15, 2020, 3:43am UTC](https://boards.straightdope.com/t/masks-to-keep-out-the-bad-while-letting-in-the-good-for-pennies/925462/10 "2020-11-15T03:43:53Z")
There were better options even then. I bought some HEPA vacuum cleaner bags, made of several layers of blown plastics, and inserted a piece of that into a fabric mask (made of quilting cotton). With a bit of aluminum wire to shape the top to my nose, it was a pretty decent mask. Now I use either a surgical mask or a Stark’s fabric mask (made by the people i bought the vacuum bags from) for knocking around the neighborhood, and an N90 respirator for grocery shopping. If you want something cheap per use, the Stark’s mask is washable, reasonably priced, includes a layer that’s supposed to be a filter, and is really comfortable, at least on my face. ---
**Author:** ![needscoffee](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/needscoffee/32/1076_2.png) [@needscoffee](https://boards.straightdope.com/u/needscoffee)\ **Post date:** [November 15, 2020, 3:50am UTC](https://boards.straightdope.com/t/masks-to-keep-out-the-bad-while-letting-in-the-good-for-pennies/925462/11 "2020-11-15T03:50:39Z")
> [@rboyce](#): > > Then using two (2) filters gives you 100% protection and three (3) filters gives you 150% protection. > if my numbers are right; which they are Putting filters together doesn’t make the holes in each one any smaller. ---
**Author:** ![Acierocolotl](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/acierocolotl/32/6241_2.png) [@Acierocolotl](https://boards.straightdope.com/u/Acierocolotl)\ **Post date:** [November 15, 2020, 10:52am UTC](https://boards.straightdope.com/t/masks-to-keep-out-the-bad-while-letting-in-the-good-for-pennies/925462/12 "2020-11-15T10:52:55Z")
A screen door doesn’t keep the rain out. FIfty times the screens still don’t keep the rain out but may slow it down for awhile. Thing is, when you’re in a submarine, a screen door should be near the bottom of the list as a tool to repair your hull. You know? Stopping 50% of the particles is not good. If you’re exposed to 50,000 potentially infectious particles per breath, reducing that to 25,000 isn’t exactly a happy day. Inhaling particles is like inhaling flying bullets. Only getting shot half the time isn’t exactly a winning situation for the guy getting shot. So again, I’m going to call your attention to Table 1. It’s in Chapter 2.2, “Filter materials,” which you really can’t miss unless you’re trying to be difficult. The qF score is a measure of the penetration efficiency of particles (expressed as 1-η) divided by the delta pressure drop P. So high pressure drops (read: difficulty breathing through the filter) result in low scores. Being bad at stopping particles also means a bad score. The best on the list is the BestAir Household air filter, with a qF of 7.2. A Jinjiang-brand KN95 mask has a qF of 5.9. A vacuum-cleaner bag from Hoover rates a 3.09. Some activated carbon nonsense rates a 1.22. The best coffee filter tested rated a 0.34, and the only thing that scored worse than that was another coffee filter, at 0.29. Even a Levi’s bandana did better than the coffee filters, with 0.37. So there’s a bit of science for you, and we can conclude that of the various things tried, the coffee filters are the worst. I can’t really make that any clearer. Even if you find the mythical perfect coffee filter and stack them 30-deep, they’re still only as good as your ability to seal them on your face anyway. At the least, tie the filters on your face with a bandana. The bandana can do better filtration and you could use the coffee filters to actually filter some coffee! Pour some grounds in there, everything would smell nice and you could tell people you were the Coffee Bandit. Win/win there, as far as I’m concerned. ---
**Author:** ![rboyce](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rboyce/32/4066_2.png) [@rboyce](https://boards.straightdope.com/u/rboyce)\ **Post date:** [November 15, 2020, 3:43pm UTC](https://boards.straightdope.com/t/masks-to-keep-out-the-bad-while-letting-in-the-good-for-pennies/925462/13 "2020-11-15T15:43:53Z")
If I microwave my mask will this kill any pathogens that might be on it? ---
**Author:** ![rboyce](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rboyce/32/4066_2.png) [@rboyce](https://boards.straightdope.com/u/rboyce)\ **Post date:** [November 15, 2020, 3:57pm UTC](https://boards.straightdope.com/t/masks-to-keep-out-the-bad-while-letting-in-the-good-for-pennies/925462/14 "2020-11-15T15:57:07Z")
If I microwave my mask will this kill any pathogens that might be on it? **YES** > **[Does Microwaving Masks Disinfect Viruses? – Smart Air](https://smartairfilters.com/en/blog/microwaving-masks-disinfect-covid-virus/)** > > We tested particle capture before and after microwaving masks. Test data shows microwaving deactivates viruses, with no detectable effect on performance. ---
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [November 15, 2020, 4:56pm UTC](https://boards.straightdope.com/t/masks-to-keep-out-the-bad-while-letting-in-the-good-for-pennies/925462/15 "2020-11-15T16:56:58Z")
Thanks for this article, by the way. I knew my vacuum filter was a little hard to breath through, but I’m happy to see it probably was pretty good at filtering out the virus. I’d love to see an updated article for the fabric masks now on the market – popular brands and common styles. ---
**Author:** ![needscoffee](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/needscoffee/32/1076_2.png) [@needscoffee](https://boards.straightdope.com/u/needscoffee)\ **Post date:** [November 15, 2020, 7:27pm UTC](https://boards.straightdope.com/t/masks-to-keep-out-the-bad-while-letting-in-the-good-for-pennies/925462/16 "2020-11-15T19:27:10Z")
> [@rboyce](#): > > If I microwave my mask will this kill any pathogens that might be on it? Soap and water will kill covid, too, which is why we’re instructed to wash our hands for 20 seconds. You can hand-wash your fabric mask in the sink. ---
**Author:** ![Acierocolotl](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/acierocolotl/32/6241_2.png) [@Acierocolotl](https://boards.straightdope.com/u/Acierocolotl)\ **Post date:** [November 15, 2020, 9:32pm UTC](https://boards.straightdope.com/t/masks-to-keep-out-the-bad-while-letting-in-the-good-for-pennies/925462/17 "2020-11-15T21:32:07Z")
I wonder if this article would be of any value to you? [https://www.cbc.ca/news/canada/marketplace-masks-test-1.5795481](https://www.cbc.ca/news/canada/marketplace-masks-test-1.5795481) I haven’t really looked at it in much detail (I noticed it last week) but there appears to be exactly what you’re looking for in there. ---
**Author:** ![rboyce](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rboyce/32/4066_2.png) [@rboyce](https://boards.straightdope.com/u/rboyce)\ **Post date:** [November 23, 2020, 2:09am UTC](https://boards.straightdope.com/t/masks-to-keep-out-the-bad-while-letting-in-the-good-for-pennies/925462/18 "2020-11-23T02:09:53Z")
Below are a few more precautions when using masks that I did not state in the beginning **[1]** Do not smell your mask **[2]** Do not touch the outside surface of your mask **[3]** Do not give or loan your mask to anyone **[4]** \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ suggest something ---
**Author:** ![JaneDoe42](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/janedoe42/32/14104_2.png) [@JaneDoe42](https://boards.straightdope.com/u/JaneDoe42)\ **Post date:** [November 23, 2020, 6:08am UTC](https://boards.straightdope.com/t/masks-to-keep-out-the-bad-while-letting-in-the-good-for-pennies/925462/19 "2020-11-23T06:08:25Z")
> [@rboyce](#): > > If I microwave my mask will this kill any pathogens that might be on it? I know for a fact that if you microwave coffee filters for longer than 10 seconds they will catch fire as soon as you open the door and grab them. I also didn’t think that coffee filters were still a thing, doesn’t everyone have a Keurig nowadays? **[4]** Do not put hole in mask to allow you to smoke tobacco. Nobody wants that stinky stuff anywhere near them. ---
**Author:** ![FigNorton](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fignorton/32/5619_2.png) [@FigNorton](https://boards.straightdope.com/u/FigNorton)\ **Post date:** [November 23, 2020, 12:28pm UTC](https://boards.straightdope.com/t/masks-to-keep-out-the-bad-while-letting-in-the-good-for-pennies/925462/20 "2020-11-23T12:28:40Z")
> [@JaneDoe42](#): > > I also didn’t think that coffee filters were still a thing, doesn’t everyone have a Keurig nowadays? Yes, I have a Keurig. I duct taped 5 of the pods together for my masks. Used ones seem more breathable. I’m afraid I have no choice but to smell my mask. The scent is rather overwhelming. [Next page](https://boards.straightdope.com/t/masks-to-keep-out-the-bad-while-letting-in-the-good-for-pennies/925462.md?page=2)