Have you been overwhelmed trying to choose the best face mask filter material? I know I have!
Without specialist equipment, it’s difficult to know how well a material filters out particles. And there isn’t much data out there.
Business Insider recently covered a new study that tested popular filter ideas.
From furnace filters to vacuum bag linings, 20 materials were tested in a lab by particle-testing company TSI. They tested how well each material captured particles, and how breathable they were.
This article is focused on sharing the best and worst filter materials found in the study.
There are some surprises in store for you! (Hint: you’ve probably been recommended the poor performing filters a lot).
The researchers did say, however, that filtration isn’t the only thing to consider. A good fit is important too. Here are some tips from hospitals on how to create a better fitting mask.
Note: this is an informational post. It is not medical advice. Please talk to a doctor or medical professional for medical advice.
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Contents list:
- About the TSI face mask filter study.
- Results: the best filter ideas (with face mask material charts).
- Results: the worst filter ideas.
- Don’t forget about face mask fit!
- Is Filti a good face mask filter material?
- Is 1500 Filtrete furnace filter a good face mask material?
- Is 99.7% Vacuum bag lining a good filter material?
- Is flannel good for face masks?
- Is shop towel a good face mask material?
- Are paper towels a good filter material?
- Is Polypropylene a good face mask filter material?
- Are coffee filters a good face mask filter idea?
- Is Kona quilting cotton a good face mask fabric?
- Is fusible interfacing a good filter material?
- Is craft felt a good face mask lining fabric?
- Which face mask filter materials are washable?
The face mask filter study by TSI & Schempf
Particle-testing equipment company TSI teamed up with fashion designer Chloe Schempf for this study.
Schempf sent the company 20 samples of popular filter material suggestions from the internet.
TSI tested them using the same machine and test procedure used to give N95 masks their NIOSH certification.
Schempf told me this is a more accurate way to test the materials:
“Many universities and labs are giving results that are not totally accurate – a spectrometer or a laser particle tester are not the best instruments for this testing and TSI filtration engineers have given me some very good info why this is – but I haven’t had a chance to add this to the site in a less technical form.”
C. Schempf via email correspondance on 8 May 2020.
What particles did TSI test for?
‘The COVID… virus is smaller than 0.3, at about 0.1 microns, but 0.3 microns is a sort of magic size to test for, according to Kennedy [the President of TSI]. That’s because this size particle is the most difficult to capture, he says. Particles that are bigger, as well as particles that are smaller will be trapped by filters that capture 0.3 microns. So this test of fabrics, “certainly covers the size range for the virus,” Kennedy says.’
J. Bort (2020) on Business Insider [published: 25 April 2020].
Here are some limitations of this study:
“These test results are provided for informational purposes only and do not take into account mask fit or real-world usage, should not be interpreted as recommendation or advice, and are not approved by any regulatory agency.”
TSI & Schemph. Source: https://maskfaq.com/#test-results [accessed: 7 May 2020]
You can read more about how the test happened on their test results website.
Schemph is also selling face masks. She designed them using the Filti material, the studies top performer. You can purchase 2 different styles here.
The best face mask filter materials (comparison charts)
Face mask material efficiency chart
The filter materials that captured the most particles were:
- 84.03% of particles filtered: 1 layer Filti + 1 layer 6.5g Cotton Ripstop.
- 80.85% of particles filtered: 2 layers Kona 100% Cotton + 1 layer 1500 Filtrete Furnace Filter.
- 68.48% of particles filtered: 2 layers Kona 100% Cotton + 99.7% Vacuum bag lining (no paper) + 1 layer Swiffer Dry Sheet.
View full size chart here.
7 June 2020 update: the researchers have tested even more materials. The new top performers are:
- 100.04% of particles filtered: Roc Lon Lining Fabric Budget Blackout Fabric. It was not breathable at all, however!
- 97.85% of particles filtered: 2 layers Filti.
- 86.69% – 87.62% of particles filtered: 1 layer Filti.
- 85.3% of particles filtered: 2 layers (blue and white) of Halyard H600 surgical wrap. (Note: there’s some debate about this material).
Face mask filter materials you can breathe through (comparison chart)
The ideal filter has good filtration ability and is easy to breathe through.
Here’s how breathable the highest filtering materials were, starting with the easiest:
- 8.15 mm H20: 2 layers Kona 100% Cotton + 1 layer 1500 Filtrete Furnace Filter.
- 10.82 mm H20: 2 layers Kona 100% Cotton + 99.7% Vacuum bag lining (no paper) + 1 layer Swiffer Dry Sheet.
- 13.33 mm H20: 1 layer Filti + 1 layer 6.5g Cotton Ripstop.
7 June 2020 update: the researchers have tested even more materials. The breathability of the new top performers is:
- 8.07 – 9.72 mm H20: 1 layer Filti.
- 14.58 mm H20: 2 layers Filti.
- 19.88 mm H20: 2 layers (blue and white) of Halyard H600 surgical wrap. (Note: there’s some debate about this material).
- 190.28 mm H20!: Roc Lon Lining Fabric Budget Blackout Fabric.
Wait, what do these numbers mean? mm H20 is a way to measure a material’s resistance to airflow, aka. “pressure drop”.
The higher the number, the harder the material is to breathe through.
For comparison, a typical N95 mask has a pressure drop of about 9 mm H20. The maximum that NIOSH will allow an N95 to reach is 35mm H20.
Based on this, I concluded that all the materials tested in this study are technically breathable. They all have a pressure drop that’s under 35 mm H20.
However, you as an individual might still find breathing uncomfortable.
A sizeable number of healthcare workers complain about breathing difficulties when wearing an N95 mask, even though it has an acceptable pressure drop of under 35mm H20.
A recent update (7 May 2020) on the face mask study website explains that anything over 15 mm H20 is not ideal:
“If the pressure exceeds 15 mm H20 you start to gain a vacuum effect and essentially start to suck air from the sides of your mask losing the benefits of the mask. It will also be uncomfortable and hard to breathe.”
C. Schempf (2020). Source: https://www.maskfaq.com/test-results [accessed: 7 May 2020]
View full size chart here.
Comparison chart: which filter materials are good at filtering and breathable?
View full size chart here.
The researchers from the study concluded that:
“From these test results, it appears the best material for homemade masks is Filti brand mask material. Two layers of blue shop towels is perhaps the most economical option. Two layers of 100% cotton had the worst filtration efficiency, and coffee filters had the worst breathability. Keep in mind many homemade materials tested here may not be approved for mask usage, contact the manufacturer for safety information.”
C. Schempf (2020). Source: https://www.maskfaq.com/test-results [accessed: 7 May 2020]
Are these materials safe?
16 MAY 2020 UPDATE: Walmart has a warning on their Toolbox shop towel page that says “WARNING: This product contains chemicals known to the State of California to cause cancer and/or birth defects or other reproductive harm www.p65warnings.ca.gov”
Filti says their material is safe to use in a mask.
Their material is 3 light-weight layers of Polypropylene, Nanofiber, and Polyester composite filter media.
“We designed this — the Filti face-mask material — so people can use it in a cotton mask or they can use it 100% by itself,” Filti’s founder, Andy McDowell, told Business Insider.
J. Bort (2020) on Business Insider. Source: https://www.yahoo.com/news/nanofiber-mask-fabric-manufactured-oklahoma-123500898.html [published: 26 April 2020]
Here are some video reviews about it.
Are Filtrete furnace filters safe?
Filtrete says their furnace filter is “for residential use only”. They don’t support people using their material in face masks because the safety is unknown. They have done no testing. Click here to see their direct quote.
Are vacuum bag linings safe?
This is debated by people in the vacuum industry. I summarised who says vacuum bag linings are safe, and who says they should be avoided. Click here to jump to that section.
Is 80% filtration nearly as good as an N95?
An 80% filtration score doesn’t make it similar to an N95:
“…it’s not a linear progression: A mask that filters at 95% efficiency is vastly more protective than one that filters at 80%, while a mask that filters at 80% is only modestly more protective than one that filters at, say, 60%. So even 80% is not to be confused with close-to-N95 protection.”
J. Bort (2020) on Business Insider. Source: https://www.businessinsider.com/the-materials-that-filter-particles-best-in-homemade-masks-testing-2020-4?r=US&IR=T [published: 25 April 2020]
“The N95 respirator mask filters at least 95% of particles that measure 0.3 microns. There’s a lot of science to get to that 95-percent-or-better number that home sewers simply can’t replicate. This includes factors like the special electro-static material used in the masks, as well as considerations taken to mitigate the impact of moisture build-up from the user’s breath.”
J. Bort (2020) on Business Insider. Source: https://www.businessinsider.com/the-materials-that-filter-particles-best-in-homemade-masks-testing-2020-4?r=US&IR=T [published: 25 April 2020]
Worst face mask filter materials
The worst filters in the study had very low filtration ability and/or were harder to breathe through.
The results were surprising to me because these are some of the most recommended materials for DIY face masks!
- 2 layers Kona 100% Quilters Cotton – 7.02% of particles filtered & pressure drop of 6.49 mm H20.
- Folded Bandana – 9.65% of particles filtered & pressure drop of 3.38 mm H20.
- 2 layers Braun Coffee Filter – 14.1% of particles filtered & pressure drop of 16.42 mm H20.
For comparison, an N95 mask typically has a pressure drop of 9 mm H20 and a minimum filtration of 95%.
The study researchers explain that anything over 15 mm H20 is not great.
The material will start to create a vacuum effect at this point, forcing you to suck air from outside the mask. This will make the mask less effective and is challenging to breathe through.
This rules out the coffee filter which had a pressure drop of 16.42 mm H20.
The pros with these materials are that they provide at least some filtration and they’re easy for the public to get.
Heads up: This post includes affiliate links like Amazon ones, so I earn from qualifying purchases (at no cost to you). Thanks for using them 🙂
Don’t forget about face mask fit!
You want your mask to be snug around your nose, cheeks, and chin. If it’s loose, unfiltered air will sneak in.
A recent study by S. Guha at the University of Chicago and colleagues found that just “a 1% gap reduced the filtering efficiency of all masks by half or more”.
Use skin adhesive tape
Healthcare provider Unity Point Health recommends using skin adhesive to create a seal between your face and mask.
Insert a nose wire
You could also include a nose wire to create a better fit around your nose and cheeks.
The University of Florida Health recommends using a 16-gauge craft wire. If unavailable, use 20-gauge.
They recommend cutting and bending the ends of the wire with jewelry pliers (that have tapered round ends) and a cutter.
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Is Filti a good face mask filter material?
With the help of 1 layer of cotton ripstop, ‘Filti face mask material’ captured the most particles in the study (84.03%).
The researchers behind the study like it: “from these test results, it appears the best material for homemade masks is Filti brand mask material.”
The founder of Filti also says it’s safe to use in a face mask or by itself. These are big pluses.
It’s also relatively breathable, but when used with cotton it resists airflow more than an N95 mask (Filti = 13.33 mm H20. N95 = 9 mm H20). Some may find it uncomfortable.
7 June 2020 update: the researchers have done more testing on Filti. They found:
- 2 layers of Filti captured 97.85% of particles. The pressure drop was 14.58 mm H20.
- 1 layer of Filti was tested twice. It captured 86.69% and 87.62% of particles in each test. It had a pressure drop of 8.07 and 9.72 mm H20.
PS. If you’re wondering what cotton ripstop is, it’s 100% cotton with a boxed or diamond-shaped pattern woven into the fabric. It’s heavier than most cotton’s and relatively tear-resistant. It’s often used for backpacks, outdoor clothing, sportswear, and army uniforms.
What’s Filti face mask material?
It’s a lightweight face mask filter fabric. It’s made from 3 layers of Polypropylene, Nanofiber, and Polyester composite filter media.
Filti says it’s “designed to safeguard you and your family from several airborne particles including bacteria and viruses”. The founder says it was designed with face masks in mind.
It comes in sheets in the following sizes:
- 21 sq. ft sheet – enough for 50 to 80 masks.
- 107 sq. ft sheet – enough for 250 to 400 masks.
- 215 sq. ft sheet – enough for 500 to 800 masks.
Here’s a Filti employee showing how Filti material compares to a cotton mask and a cotton t-shirt. He does a smoke test to show the differences in filtration:
Here are some video reviews of Filti’s product:
Is Filti material safe for face masks?
The founder of Filti says it’s safe and was designed specifically for DIY face masks:
“We designed this — the Filti face-mask material — so people can use it in a cotton mask or they can use it 100% by itself,” Filti’s founder, Andy McDowell, told Business Insider.
J. Bort (2020) on Business Insider. Source: https://www.yahoo.com/news/nanofiber-mask-fabric-manufactured-oklahoma-123500898.html [published: 26 April 2020]
Is Filti material washable or reusable?
As of 4 May 2020, Filti does not claim their face mask material is washable or reusable (on their product page or datasheet). I would treat it as single-use only.
11 MAY 2020 UPDATE: Filti made a Youtube video showing a way to clean their material using an oven.
Filti face mask material for sale:
Blogger Sew Can She managed to get a 10% off coupon code for her readers. Check her article to get the code.
Is 1500 Filtrete Furnace Filter a good face mask material?
Yes, in terms of filtration and breathability.
It captured 80.85% of particles and had a pressure drop of 8.15 mm H20 (an N95 is typically 9 mm H20).
However, Filtrete is clear in saying they don’t support people using their furnace filters in masks. It’s not designed for this use, so they don’t know how safe it is.
What’s 1500 Filtrete Furnace Filter?
1500 Filtrete Furnace Filter is ahome air filterfor your furnace, air conditioner, or HVAC system.
Its purpose is to attract and capture microscopic particles like:
- Bacteria.
- Viruses.
- Smoke.
- Cough/sneeze debris.
- Large particles, including lint, household dust, and pollen.
“Filtrete” is the brand name.
“1500” is the MPR (Microparticle Performance Rating). The higher this number is, the more microparticles (like bacteria and viruses) the filter will capture from the air passing through it.
Is 1500 Filtrete Furnace Filter safe for face masks?
Filtrete have warned that no testing has been done to check the safety of their filters as face masks. They do not recommend or support people DIYing their products into masks.
“Can we use the Filtrete™ Air Filter material/media to create handmade masks?
Filtrete (2020). Source: https://www.filtrete.com/3M/en_US/filtrete/home-tips/full-story/~/coronavirus-and-important-things-to-know-about-airborne-particles/?storyid=d69e7735-c02c-46d2-9c8a-ae23372934ac [published: 23 March 2020]
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.”
Blogger Sew Can She got in touch with Filtrete to ask if their filters have fiberglass in them. Here’s the response she got:
“Our filters are made from Polypropylene plastic fibers and strands, adhesive, paperboard, and for some filters, metal wire. There is no Fiberglass in our Filters.
However, our Filtrete brand products are designed to be used in your home and your HVAC systems.
The filter media in a Filtrete brand filter performs very differently than an approved N95 respirator or mask. It cannot achieve the fit or performance of a mask or N95 respirator and modifying the furnace filter may damage the material.
3M does not recommend or support the use of a Filtrete brand filter to make a mask or respirator.”
From Sew Can She. Source: https://www.youtube.com/watch?v=x64QdUl5mgE in the description section [accessed: 7 May 2020]
Is 1500 Filtrete Furnace Filter washable or reusable?
Filtrete does not claim its furnace filter is washable or reusable. I would treat it as single-use only.
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Is 99.7% Vacuum bag lining (no paper) a good face mask filter material?
It filtered 68.48% of particles with the help of cotton and Swiffer dry sheet. It wasn’t the best performer, but that’s still a decent filtration for a DIY mask.
These 3 materials were only a bit harder to breathe through than an N95 at 10.82 mm H20 (an N95 is normally 9 mm H20).
What is 99.7% Vacuum bag lining (no paper)?
These are used inside vacuums (aka. hoovers) to filter and collect dust and other particles.
Here’s what they look like cut up:
Is Vacuum bag lining safe for face masks?
There are mixed opinions about the safety of vacuum bags.
Josh Wolcott of Vacuums R Us near Denver, CO says they’re safe (see video below). He says the idea that vacuum bags contain fiberglass is a myth.
He contacted multiple manufacturers and looked at safety data sheets. He said he found no vacuum bags that contained fiberglass.
Vacuum Cleaner Market in Morgan Hill, CA agrees. They said “vacuum bags have not ever, and do not contain fiberglass”.
However, vacuum bag manufacturer Shop-Vac is telling people not to use their products in face masks.
They say their filters aren’t designed for this use. They didn’t mention anything about fiberglass, though.
“Under no circumstances should anyone attempt to make a mask or mask material from any filters manufactured, sold or distributed in the market for or by Shop-Vac Corporation. These materials were not designed, intended or designated for this type of use.”
Shop Vac Store. Source: https://www.shopvacstore.com/default.aspx [accessed: 30 April 2020]
Is Vacuum bag lining washable or reusable?
I haven’t seen it advertised on product pages as washable or reusable. I would treat it as single-use only.
Is flannel a good face mask material?
1 layer of Kona quilting cotton and 1 layer of flannel captured 15.39% of particles. This performed better than 2 layers of Kona quilting cotton which only captured 7.02% of particles.
To increase the filtration efficiency of a cotton & flannel mask you could add more layers in between.
The cotton & flannel lining combination had a pressure drop of 8.08 mm H20. For comparison, a typical N95 mask is 9 mm H20, so it was slightly easier to breathe through than an N95.
What’s flannel?
Flannel or Flannelette fabric is brushed during manufacturing to give it a soft, fuzzy feel on both sides. This means it also traps heat.
It’s common to find cotton flannel, although it can be made from other fibers.
Is flannel safe for face masks?
My understanding is that flannel fabric is OK to wear on our faces. Flannel has also been recommended by some hospitals as an acceptable face mask material.
Is flannel washable or reusable?
Yes, flannel fabric can be washed and reused.
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Is shop towel a good face mask filter material?
The study tested shop towels made by Toolbox. 2 layers of it captured 41.94% of particles. It did better than 12 other materials tested in the study.
It had a pressure drop of 11.98 mm H20. For comparison, an N95 is normally 9 mm H20, so the shop towels are harder to breathe through.
It’s still below 15 mm H20, however, which the researchers considered the maximum a material should be.
After 15 mm H20, a vacuum effect is created and you’re forced to suck unfiltered air from gaps in the mask.
This is something to be aware of if you’re pairing the shop towels with something else. For example, if you want to use the towels as a face mask insert with 2 layers of quilting cotton, it would increase the pressure drop by 6.49 mm H20. The total pressure drop would then be over 15 mm H20.
What are shop towels?
Home Depot says they’re absorbent towels “designed for cleaning up grease, liquids, oils and spills in automotive repair shops and garages”.
They’re made from paper waste, tree fibers, and synthetic latex resin.
Here’s a video from Toolbox that shows how they’re made:
Are shop towels safe for face masks?
16 MAY 2020 UPDATE: Walmart has a warning on their Toolbox shop towel page that says “WARNING: This product contains chemicals known to the State of California to cause cancer and/or birth defects or other reproductive harm www.p65warnings.ca.gov”
In the Q&A section of Home Depot, a customer asked “are there any chemicals or fiberglass used in the making of these towels that would [be] harmful if breathed through?”
On 21 April 2020, the Sellars Product Expert replied (note: Sellars is the company that owns Toolbox):
“No, there are no chemicals or fiberglass in the shop towels. Our product is used for cleaning purposes, it’s not meant for PPE use or making PPE items. We do not recommend or advise anyone to utilize our product to make or for use as PPE (face masks).”
Sellars Product Expert. Source: https://www.homedepot.com/p/TOOLBOX-Blue-Shop-Towels-200-Count-Box-6-Boxes-per-Case-55202/205218066 [published: 21 April 2020]
Are shop towels washable and reusable?
According to a Sellars representative on Home Depot (in the Q&A section), shop towels are disposable and cannot be washed.
Are paper towels a good face mask filter material?
In this study, 4 layers of Viva paper towels captured 22.54% of particles. Not incredible, but that’s still triple the filtration of just 2 layers of Kona quilting cotton.
I thought 4 layers might make it harder to breathe through, but actually the test results show the opposite. It had a pressure drop of 3.37 mm H20. An N95 is normally 9 mm H20.
One way to increase its filtration is to use it with cotton. You can make a normal 2 layer face mask with a filter pocket (here are some face mask sewing patterns if you need them), and just insert 4 layers of paper towel inside.
What are paper towels?
These are disposable towels used for cleaning. They’re made from wood pulp (from trees). In the UK, paper towels are known as kitchen roll.
Are paper towels safe for face masks?
My understanding is that paper towels are safe.
Are paper towels washable or reusable?
Paper towels are designed to be disposable. If you try to wash them, they might disintegrate.
Is Polypropylene a good face mask filter material?
Several materials in this study were made from polypropylene, either fully or partially.
Uline lightweight oil absorbant pad (not dimpled)
Assuming this is the product used in the study, it’s made from 100% polypropylene. 1 layer of it captured 35.02% of particles and it had a pressure drop of 2.67 mm H20. The product description says it’s “not reusable”.
Filti face mask material
This is partially made from polypropylene. In combination with cotton ripstop, it captured 84.03% of particles and had a pressure drop of 13.33 mm H20. Learn more about it here.
1500 Filtrete Furnace Filter
This is partially made from polypropylene. In combination with Kona quilting cotton, it captured 80.85% of particles and had a pressure drop of 8.15 mm H20. Learn more about it here.
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Are coffee filters a good face mask filter material?
At one point, coffee filters were recommended by the Centers for Disease Control.
They used it in their no-sew bandana face mask tutorial. However, I noticed on the 13th April 2020 they had quietly edited the tutorial and removed the coffee filter. There was no explanation.
This study could provide some answers: it turns out coffee filters are hard to breathe through and don’t filter particles well.
The coffee filter in the study captured 14.1% of particles (an N95 captures 95%+) and it had a pressure drop of 16.42 mm H20 (an N95 is 9 mm H20).
The researchers from the study explained that anything over 15 mm H20 is not great.
The material will start to create a vacuum effect at this point, forcing you to suck air from outside the mask. This will make the mask less effective and is challenging to breathe through.
What is a coffee filter?
These are disposable paper filters used when brewing coffee. They have tiny pores that allow coffee to flow through while still holding back small coffee grains.
Are coffee filters safe for face masks?
Paper coffee filters are made from trees. My understanding is that this is safe.
Are coffee filters washable or reusable?
Paper coffee filters are designed to be disposable. You can get a pack of 100 for under $7.
Note: The white paper filters have been bleached with chlorine or air. The brown ones are natural (source).
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Is Kona quilting cotton a good face mask fabric?
2 layers of quilting cotton is the most recommended material for face masks by hospitals.
In this study, it didn’t filter well, but it was easy to breathe through. It captured 7.02% of particles and had a pressure drop of 6.49 mm H20 (an N95 is normally 9 mm H20).
I think a big reason for this poor filtration is the thread count. Kona quilting cotton has a thread count (per inch) of 120. Whereas some hospitals and studies are recommending quilting cotton with thread counts of 600+!
What’s Kona quilting cotton?
Kona quilting cotton is a medium weight fabric that weighs 4.35 oz. per square yard or 150gsm. The thread count is 120 (aka. 60 x 60). It’s 100% cotton. “Kona” is the brand name.
Is Kona quilting cotton safe for face masks?
My understanding is that wearing cotton on our faces is safe.
Is Kona quilting cotton washable or reusable?
Cotton is washable and reusable.
Is fusible interfacing a good face mask filter material?
The study tested 2 layers of medium weight fusible interfacing from Pellon.
It was the easiest material to breathe through in the study, with a pressure drop of 1.08 mm H20. An N95 is normally 9mm H20.
Its filtration ability wasn’t amazing: it captured 17.24% of particles.
However, if you combined it with 2 layers of quilting cotton it would capture slightly more. You could do this by making a 2-layer face mask from cotton and then inserting 2 layers of interfacing inside.
What is fusible interfacing?
It’s a material used to stabilize fabrics.
The study tested a specific version:
- It was fusible, which means it had glue on it that melts and sticks to the fabric it’s stabilizing.
- It’s medium weight.
- It’s non-woven.
- It’s made by the brand Pellon.
- It’s most likely made from 100% polyester (based on Pellons product description for interfacing that meets the above criteria. However, I can’t be sure that it’s the exact product the study used).
Is fusible interfacing safe for face masks?
I can’t find any claim on Pellon’s website that says their product can be used in a face mask.
My personal understanding is that non-woven polyester fabric is not harmful to wear on our faces. If you want to avoid the glue, you can choose a sew-in interfacing instead.
Is fusible interfacing washable or reusable?
Yes, you can machine wash and tumble dry it. Pellon do not recommend using fabric softener. Product details are available here, however I can’t guarantee that it’s the same product used in the study.
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Is craft felt a good face mask filter fabric?
This combination of craft felt, shop towel, and bandana captured 36% of particles.
Not incredible, but still better than 10 samples in the study (which includes 2 layers of cotton or a bandana).
In terms of breathability, it’s similar to an N95 (craft felt combination = 9.78 mm H20. N95 = 9 mm H20).
What is craft felt?
Craft felt is a non-woven fabric typically made from 100% polyester, however you can get wool and other blends too. It’s unclear which type the study used, but I have assumed their “craft felt” was a typical polyester one.
Is craft felt safe for face masks?
My personal understanding is that non-woven polyester fabric is not harmful to wear on our faces.
Is craft felt washable or reusable?
Based on craft felt I found at Joanns, yes it is. You can machine wash it on a gentle, cool cycle and tumble dry it on a low setting. Chlorine bleach is not allowed.
Which face mask filter materials arewashable?
Please note that washing materials may or may not remove COVID particles.
Here are washable materials that were tested in the study:
- Cotton fabric: t-shirt and woven cotton.
- Fusible interfacing.
- Craft felt.
- Flannel fabric.
- Rayon fabric.
- Bandana.
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Sources
C. Schempf (2020). ‘Michigan Mask Response and Filter Research’ [online] Available at: https://www.gofundme.com/f/michigan-mask-response [accessed: 27 April 2020]
C. Schempf. ‘DIY MASK FAQ’. [online] Available at: https://maskfaq.com [accessed: 27 April 2020]
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