Learn the pros and cons of various types of materials and fabrics currently being used in face mask filters, and whether or not you need one at all in your DIY face mask.
Several weeks ago, my brother-in-law — who is a respiratory therapist at our local hospital — contacted me to make a pattern for DIY face masks. I made a pattern, tutorial, and step-by-step video, and it’s helped hundreds of thousands of people create their own homemade face mask. A couple of days ago, the CDC issued a statement recommending everyone wear cloth face coverings in public settings (e.g., grocery stores and pharmacies). Since then, we’ve been getting a ton of questions about making DIY face masks, including what sort of filter — if any — to include. So let’s talk about DIY Face Mask filter materials, and whether or not you need one at all.
My free pattern to make your own DIY face mask
Important Note: As research and testing continues into face mask filter materials, I will update this list to help you make the most informed decision for your DIY face mask making efforts. It’s critical to note that a material’s inclusion on this page does NOT make it suitable. I’m simply gathering evidence-based research and manufacturer’s safety sheets to help you make a more informed decision.
Looking for my DIY face mask tutorial? You’ll find it here!
Watch the full step-by-step video on how to make the DIY Face Masks on a Cricut or by hand here!
Note: In my video which I made two weeks ago, I mentioned using a HEPA air filter and a HEPA vacuum cleaner bag filter, HOWEVER, since then new information has come to light that calls into question their safety and I no longer recommend these items, and won’t until I have definitive evidence that these DIY filter materials are safe. Read more below.
Do I really need a filter in my DIY face mask at all?
The CDC’s sewn cloth face covering materials list (see the CDC’s Cloth Face Covering information and material suggestions) calls for just two layers of “cotton fabric.” My research backs this up. A Cambridge University study in 2013 tested the effectiveness of homemade mask materials. Their conclusion was that one layer of cotton T-shirt material and one layer of tightly woven cotton fabric (like a pillowcase) was a better combination, and would each capture 61-69% of 1-micron particles, which is smaller than what we produce when we cough or sneeze (Atkinson, 2009). The study found that a homemade face mask was MUCH better than no mask at all.
The Cambridge University researchers said, “The pillowcase and the 100% cotton T-shirt were found to be the most suitable household materials for an improvised face mask. The slightly stretchy quality of the t-shirt made it the more preferable choice for a face mask as it was considered likely to provide a better fit.” (Davies, Thompson, Giri, Kafatos, Walker, Bennett, Allan, 2013)
Additionally, “The filtration efficiency of improvised fabric materials is comparable to some commonly used Federal Drug Agency-cleared surgical masks and unapproved dust masks” (The Annals of Occupational Hygiene, Volume 54, Issue 7, October 2010, Pages 789–798, https://doi.org/10.1093/annhyg/meq044).
My DIY Face Mask pattern with its optional filter pocket (but without a filter in place) has three layers. The Cambridge University study shows that two or more layers of cotton would increase the mask’s effectiveness to 74%.
Conclusion: Two or more layers of cotton fabric is 74% effective, and the safest, simplest option for a DIY face mask. When in doubt, skip the filter.
UPDATE: Looking for something more formal? Check out “Face Masks Against COVID-19: An Evidence Review” published on April 12, 2020 by 19 scientists. Their review gathers together available evidence at the time of its publication to help when developing policy around use of non-medical masks in public. It’s not yet peer reviewed as it just came out, but it’s an excellent overview of where we stand right now with face mask efficacy.
I have an easy Gaiter Face Mask Pattern that you can sew with a filter pocket and a nose wire.
What filter do you put in a DIY face mask?
There are a lot of filter materials being suggested on the Internet, and not all of them are safe nor breathable. The Cambridge University study made an important point about the role of breathability and comfort, saying, “If respiratory protection is not capable of accommodating the breathing demands of the wearer, then the device will impose an extra breathing load on the wearer, which is especially impracticable for people with breathing difficulties. Furthermore, the extra breathing load may induce leakage owing to the increased negative pressure in the face mask.”
A mask that a person cannot breathe through is ineffective and dangerous. So we must look at both filtration effectiveness and breathability when determining whether a filter material is appropriate for a face mask.
What follows is a list of filter materials folks have asked me about and the research, if any, I could find on their effectiveness and breathability. It’s important to note that very little scientific research has been done at this point on these materials as filters. I’m hoping this changes in the coming weeks and months, and I’ll be watching and updating this page. Please always read the Material Safety Data Sheet, when available, and do your own research.
The CDC’s bandana face covering material list calls for a coffee filter as the second layer (the first layer being the bandana). The CDC does not indicate that the coffee filters are included for particle filtration, however.
Availability: You can find typically coffee filters at grocery stores and online.
Filter Effectiveness Research: Currently, I can find no published and peer-reviewed scientific research that supports coffee filter filtration effectiveness. However, some testing has begun and preliminary tests indicate it could provide about 40-50% filtration with multiple layers.
Filter Breathability: Poor. Coffee filters are very difficult to breath through.
Blue Shop Towels
According to Business Insider, a blue shop towel made from polyester hydro knit was found to be more effective as a DIY face mask filter than other household materials. They claim that two blue shop towels inserted into an ordinary cotton mask brought filtration up to 93% of particles as small as 0.3 microns. The two brands they tested were ToolBox’s Shop Towel and ZEP’s industrial blue towel. Note that Scott’s pro shop towels didn’t work as well. Unfortunately, I cannot find any actual data on this research other than the quotes in Business Insider. When and if their findings are made public, I will link them here. My understanding is they are raising funds to send their DIY face mask made with blue shop towels to a research facility for scientific testing. Until this test is conducted, we do not know for sure if this is an effective material.
Availability: You can find typically find blue shop towels at home improvement and online (BUT, supplies have been low recently).
Filter Effectiveness Research: None. Currently, I can find no published scientific research that supports blue shop towel filtration effectiveness.
Filter Breathability: Good.
If blue shop towels work, what about regular paper towels. My research indicates paper towels are not effective. Two layers of paper towels were tested with a particle counter to see how well they filtered out .3 micron particles. Unfortunately, the two layers of paper towels were only able to capture 33% of the .3 micron particles (and on layer only managed to get 23%). That said, this would be better than nothing if you had no other alternative.
Availability: You can find typically find paper towels at grocery stores and online (BUT, supplies have been low recently).
Filter Effectiveness Research: See https://smartairfilters.com/en/blog/paper-towel-effective-against-viruses-diy-mask/
Filter Breathability: Good.
Interfacing is used to stabilize fabrics when cutting and sewing. Currently, “non-woven” interfacing is being recommended by some as an option for filter material, specifically Pellon interfacing 380, 808, 810, 830, 880F, 910, 911FF, 930, 931TD, 950F, and Oly-Fun by Fairfield. Unfortunately, I can find no research that indicates whether interfacing is at all effective.
Availability: You can find interfacing at fabric stores, some craft stores, and online.
Filter Effectiveness Research: None. Currently, I can find no published scientific research that supports interfacing filtration effectiveness.
Filter Breathability: Ok to poor. Interfacing can be hard to breath through. The Pellon 808 I tried seemed tolerable, but perhaps not for long periods of time.
Cotton Batting (Quilt Batting)
Batting is used to increase the thickness and warmth of quilts, coats, and things of that nature. I can find absolutely no evidence that supports that it provides any effectiveness at filtration — it is not closely woven and I can’t see how it would do anything other than make a mask hot and too thick for comfort. I do not recommend you use batting.
Availability: Cotton batting is at fabric stores, some craft stores, and online.
Filter Effectiveness Research: None. Currently, I can find no published scientific research that supports cotton batting filtration effectiveness.
Filter Breathability: Not great (and hot).
Dryer sheets are typically nonwoven polyester fabric covered with chemicals to help soften clothes and reduce static cling, as well as fragrances. While nearly all of the chemicals commonly found in dryer sheets are generally recognized as safe (GRAS) by the Food and Drug Administration (FDA), that does not mean they were tested as safe for use as face mask materials. Given that they are coated in chemicals and fragrances, I feel this would be a poor choice as a filter.
Availability: Dryer sheets are typically at grocery stores and online.
Filter Effectiveness Research: None. Currently, I can find no published scientific research that supports cotton batting filtration effectiveness.
Filter Breathability: Ok.
Felt can be made of wool (uncommon these days) or from synthetic fibers such as petroleum-based acrylic or wood pulp-based rayon (more typical, especially in “craft felt”). These different materials will behave differently, so it’s important to know what you have. Natural fiber felt will be more breathable and collect less condensation than synthetic fiber felt. According to the Reusability of Facemasks During an Influenza Pandemic: Facing the Flu, “Respirator and medical mask filters are typically composed of mats of nonwoven fibrous materials, such as wool felt, fiberglass paper, or polypropylene. The material creates a tortuous path, and various mechanisms result in the adhesion of particles to the fibers without necessarily blocking the open spaces, still allowing air to flow easily across the filter (Revoir and Bien, 1997).” Based on this information, a dense wool felt could do some good, but it unclear how much.
Availability: Felt is found at craft stores and online.
Filter Effectiveness Research: None. Currently, I can find no published scientific research that supports felt’s filtration effectiveness.
Filter Breathability: Ok.
A sanitary napkin (aka maxi pad) is for use by individuals who are menstruating. Unfortunately, they are saturated with chemicals, as well as a substance which swells and jells when it gets moistened to help the contents to stay put. You do not want to inhale those chemicals. I do not recommend this material, and I feel it would be a poor choice as a filter.
Availability: Sanitary napkins are typically at grocery stores and online.
Filter Effectiveness Research: None. Currently, I can find no published scientific research that supports sanitary napkin filtration effectiveness.
Filter Breathability: Poor.
Wet wipe and baby wipes are pre-moistened towels usually at least partly made of woven polyester. They are saturated with chemicals ranging from gentle cleansing ingredients to alcohol-based “cleaners”. I do not recommend this material, and I feel it would be a poor choice as a filter.
Availability: Wet wipes/baby wipes are typically at grocery stores and online.
Filter Effectiveness Research: None. Currently, I can find no published scientific research that supports wet wipe filtration effectiveness.
Filter Breathability: Ok.
Halyard 600 Medical Grade Fabric
Halyard H600 is a two-ply spun polypropylene used by hospitals to wrap surgical instrument traps, and it cannot be penetrated by water, bacteria or particles. According to the manufacturer’s specifications, it blocks 99.9% of particulates, making the masks about 4% more effective at blocking particulate material than the N95 masks (this figure is from Bruce Spiess, M.D., a professor of anesthesiology at the University of Florida College of Medicine).
Availability: Unfortunately, this material is hard to come by if you do not work at a hospital. I do see it online for sale at Amazon, but I doubt it will stay available for long (and it’s expensive).
Filter Effectiveness Research: None. Currently, I can find no published scientific research that supports using Halyard 600 as a face mask filter, but the manufacturer’s specifications indicate it may be effective. This material’s safety is unknown however.
Filter Breathability: Unknown (I have none to try breathing through)
HEPA Vacuum Cleaner Bag Filters
The Cambridge University study tested vacuum bags filters for their ability to filter out 1 micron particles, and found them to be 94.35 percent effective. Unfortunately, they did not test or address the safety of using vacuum cleaner bags as filters, as my research shows that some of these vacuum cleaner bags could contain materials that are harmful if inhaled. They are also super hard to breathe through. So despite the Cambridge University study, I will not be using these in my masks (which is fine because I have none of these anyway).
Availability: Hard to get right now
Filter Effectiveness Research: The Cambridge University study in 2013 found them to be 94% effective against 1 micron particles
Filter Breathability: Poor. Vacuum cleaner bag filters are very difficult to breath through.
3M Filtrete HEPA Air Purifier Filters (MPR 1500 and above)
Accordion-style air filters typically used for home air filtration were first recommended as a DIY face mask material by Chinese mask makers during their outbreak earlier this year. According to the manufacturer’s specifications on their web site, HVAC air filters with an MPR of 1500 or above are 54%-77% effective at capturing small particles like bacteria and particles that carry viruses, whereas Filtrete Air Purifier Filters (True-HEPA Air Filter and HEPA-Type Air Filter) are 93%-99.97% effective (this data is based on ASHRAE 52.2 testing for .3 to 1 micron particles). Despite information widely circulating, these Filtrete air filters are NOT fiberglass. You can read the Material Safety Data Sheet here. That said, the manufacturer has specifically said on their site, “Our filters are designed to be used in HVAC systems, and the filter media has not been tested to be used as a face mask for respiratory protection. Altering any of our 3M Filtrete™ Air Filters is not recommended or supported by 3M or the Filtrete™ Brand. Customer safety is our number one priority.”
Availability: You can find air filters at home improvement stores and online.
Filter Effectiveness Research: None. Currently, I can find no published scientific research that supports using HEPA air filters as a face mask filter material and the manufacturer specifically stated on their web site that “filter media has not been tested to be used as a face mask for respiratory protection.”
Filter Breathability: Good.
Air Filtration Filters (PM 2.5)
Air Filtration filters are intended for air pollution and dust, and are used as replaceable filters in respirators and masks. The question is — are they effective against small particles that can carry viruses? Researchers from the University of Edinburgh tested different common masks and used a particle counter to see how many particles made it through a mask with a PM 2.5 air filter. They found that dust respirators with filters rated for PM 2.5 were about 97%-98% effective.
Availability: Available online, but often do not ship for some time.
Filter Effectiveness Research: Langrish JP, Mills NL, Chan JK, et al. Beneficial cardiovascular effects of reducing exposure to particulate air pollution with a simple facemask. Part Fibre Toxicol. 2009;6:8. Published 2009 Mar 13. doi:10.1186/1743-8977-6-8
Filter Breathability: Good.
Can filters be washed? How often should they be changed?
If you choose to use a material as a filter, you should not attempt to wash it. There is no research to suggest this would not damage the effectiveness of a material. Instead, you should properly dispose of it and replace it at least daily.
For my personal DIY face masks, I’m sticking with multiple layers of 100% cotton, including heavyweight T-shirts, until I see compelling scientific evidence on the effectiveness and safety of another filter material. When and if I find that, I will update this page.
How do you even make DIY face masks?
Learn more about face masks and get more answers to your questions in my DIY Face Mask Guide:
Get my free pattern to make your own DIY face mask, with or without a filter!
Are you making cotton face masks? We’d love to see them! Please post over in our Facebook group — everyone is welcome! We’d love to see your Cricut face masks, too! Please share them in the group or email us at [email protected].
This is awesome I had not made any masks yet because I didn’t have anything to use as a filter. Good to know that it isn’t necessary.
Thank you so much for the time and effort you put into researching all these products. This provides me a lot of good information.
Thank you for doing all this research and sharing it. I am a data driven person and it makes all the difference in the world to me. I am making masks for my husband and his coworkers at the state prison. There are so many essential workers out there that we don’t think of right away, but are vital to society.
Thanks for the detailed info, Jennifer!! I recently saw on the news, that the reason we need to use 100% cotton fabric is that the virus can adhere to polyester fabric. FYI!
Thank you for this article. I have been looking for up to date info on what to use for filter material in my DIY masks. I’m currently using fleece from an old fleece tshirt. I’m going to bookmark this page so I can come back for updates.
Hello Jennifer. Didn’t know you were so close, right over in A². My husband is a U of M grad (even if it was when they laid the first brick, lol). Thanks for this, and all the info you share with us. I was able to find some cloth hepa vacuum bags. I plan to use those until I run out. They are 3 light layers, very breathable. I also have the oly fun…being 100% polypropylene, the research dive I did says that this material was one of the 3 layers in surgical masks, although, I can’t confirm that its processed the same way. I’m in agreement with you on adding that filter pocket….3 layers of material should suffice for most of us making “essential” runs , if a person adds a filter then that adds to their coverage. I think you are a very talented lady. I appreciate the efforts of you and other kind souls giving of yourselves and your knowledge now, and as you have in the past. May God bless and keep us all.
Thank you for this thorough analysis. I will consult this page often to obtain updates. Keep up the good work!! -Kristin in MN
Thanks for your info! I’m using a chenille craft pipe cleaner stick folded in half and lightly twisted to be the nose wire! Works like a charm and my sewing machine easily clears it!! Yay thanks bunches-luv your stuff
if you run out of pipe cleaners, a piece of aluminum foil folded over and over can be glued inside the 2 layers. Not as good but better than nothing
I’ve used the plastic coated metal ties that come in freezer bag packs. They seem to work ok too.
Thank you….Great Tip and i have those 🙂
I save the wire handles from Chinese food cartons.
Thank you for your researched information about filters for cloth masks! It’s hard to find any useful information, so kudos to you!
Thank you, Jennifer, for this information. Very timely.
This is a well-organized and well-researched article. I have been scouring the internet for evidence-based recommendations and have come up with very similar findings, and it is very helpful to see it grouped together as you have done. As a primary care doctor, I appreciate that you understand that the “best” material for a mask is based on more than what particle size it can trap. Fit, the ability to breathe, and washability are all practical considerations in real world use and affect performance. I also appreciate your understanding of the need for more studies on materials and remaining vigilant for new studies to appear.
THANK YOU for this information! I appreciate the time and effort you put into this research and making it so easily understood! Blessings!
Just wanted to say a quick thanks for the easy reference guide and updated info!
You’re welcome, Amanda.
Thanks for all your research. I have a few old heavy 100% citton tshirts and I was wondering if I could use them. I believe you have answered my question!
Great read! Can you use flannel? My mom has tons of it.
I haven’t tested flannel; however, most flannel is just cotton which is recommended. You’ll just want to test the fabric to ensure you can breathe well with the material on your face.
I have been using flannel with cotton batting for 3rd layer. We breathe through them easily, even with two layers of batting. Though it does get hot if you have to wear it for a long period of time, as you have stated. The problem with flannel and some cottons is that they unravel easily if not stitched to stop it.
Thanks for this. I haven’t seen any other research on filtration products and was wondering how much they are even worth using. I know I will have to check back and see if any of the ones not tested yet ever do and how effective and worthwhile they are.
Thank you for your research! It is most appreciated.
Kudos for your well organized, informative research. I’m very appreciative. Take care.
Found you on my email and it was the most organized and loaded info I have run across. I can now make more appropriate decisions on making the masks for myself and others. THANK YOU!
Thank you ever so much for this information on filters – I so want to make sure my family is protected and safe in these trying times.
Thank you so so so much for compiling this info! I’m exhausting from trying to do the same research and really appreciate your work to gather and share info about the various filter materials. I think I’m going to use craft felt, because I have a ready supply on hand. I did a test wash of my felt with bleach and it held up very nicely, so I’m wondering if a felt filter could be safely washed for re-use. Thanks again for compiling and sharing your research!
THank you my question was re the interfacing. I had trouble breathing thru it and now I know that is the case w that type of filter Thank you
Have you seen anything on the effectiveness of used dryer sheets? The heat removes some of the chemicals and smell. And it would give them double use.
I have not found any research on used dryer sheets to verify whether or not one use removes chemicals.
I heard that cloth grocery bag material would be a good filter instead of interfacing. Any ideas on this?
I’m not using a filter now. I just use two layers of cotton fabric. However, if you decide to use a cloth grocery bag, you’ll want to make sure that you can breathe through the fabric without any restriction.
Do you wash the cotton masks you make w tshirt material and cotton, or are they considered disposable?
Hi Lois, you can wash the masks. The CDC suggests that running it through just a regular washer and dryer should suffice for most people. However, you’ll want to do what you feel the most comfortable with based on your use.
thank you for all this information, you saved hours or looking up all the info my self. My pharmacist has asked me to make masks for his employs and families. I love your pattern and so does my pharmacist. Thank you for the great pattern You are wonderful. Thanks again
Thank you so much for the time you have taken to research these filter materials and create a pattern. There is so much out on social media and the internet in general that jumps to conclusions without thinking through the safety ramifications. You are doing a real service during the outbreak!
Thank you for the thorough research on filter materials.
Thank you for all your information and research especially on the filters!
Thank you so much for all the work you done for all of un in researching these materials. You have helped many, many, many people! XO from afar!!
It is such a pleasure to read fact-based recommendations these days. I’m a physician who also sews, and I’ve started making masks for our office staff. This is great information. Thank you!
This answered my question and brought up other things I can use as well! Thank you so much for passing on your knowledge. This has really helped me as well as many others.
Thank you so much for taking the time to help all of us. I like your design better than the typical bandana mask.
Thank you for the great information! I am an operating room nurse, and we are using the sterilization wrappers as filters in the pocket of cloth masks for our personal use (i.e. to & from work & walking through the halls, we are definitely wearing N95 masks for all surgeries). The nature of the weave makes it difficult for microbes to navigate through, giving the mask an extra layer of protection. Folks can contact their local hospitals and ask for some of these wrappers. We open our sterile supplies & bundle up the wrappers & remove them from the room before the patient is taken in to the OR. We have been giving them to people in our community who are making cloth masks.
Thanks for your continued efforts during these challenging times for everyone. Stay safe.
hi– thank you for all your information. here in Alaska we do not have the access to materials as easily as you folks in “the lower 48” so we have had to get creative. I have been using flannel from a friend who had made baby blankets and had a bag full of fabric. The outer fabric of the masks has been quilters cotton in all patterns imagined–the sight at the grocery store is quite eclectic! off to get the days quota started–it is one way to spend the “stay home” mandate useful! Thanks! Ruthe PS, my sewing area looks out–and I can see moose from time to time—there is a silver lining—yoou just have to look for ir,
Jennifer, this is great information and I love that fact that you put in references. So many people see something on the net and assume it is correct and sometimes it is down right dangerous. Thank you!!
Thank you so much for compiling this data Jennifer.
Your patterns and information have been awesome and very useful. I have an elderly neighbor who’s sister is undergoing chemo and she is worried because she can’t find any masks for the sister. I’m hoping to take care of her concerns soon Once again thanks. When thinks slow down I’m hoping to check out other stuff on your site.
My husband recently had eye surgery. They gave him his disposable pillow when we left.
I took it apart used the cover as a filter for our mask. So far breathable and washable.
New(today) subscriber here!
Thank you so very much for your detailed, researched and well written article on masks and filters, I have put a Filtrete filter in my Amazon shopping cart right now.
I have now made 27 fitted(not pleated) masks for my immediate family, plus for the seniors we love. Once these ones wear out I will be adapting your fitted mask pattern with filter pocket and add filters. I have several medical issues and have a compromised immune system and will take what you’ve written to heart.
I can’t wait to read your next post.
Quilty Huggs from Canada(near Vancouver)!
Thank you so much for this comprehensive list! I had been wanting to make masks, but felt like I didn’t know what to use.
Thank you so much for putting all this information in one easy to read and understand place! I am making masks for my little sister’s office at an ob/gyn and knowing that filter material may not actually enhance the effectiveness of the masks makes my life easier.