Action update on making your homemade masks more effective.
Nylons are once again being called to the front, the front of our faces, that is. “Researchers at Northeastern University have found that adding an outer layer made from nylon stockings to a homemade face covering can boost its ability to filter out small particles in the air by creating a tighter seal between the mask and the wearer’s face. In some cases, that extra nylon layer helped homemade cloth masks match or exceed the filtering capability of medical-grade surgical masks.” (npr)
- Create a nylon stocking overlayer made by cutting an 8-10″ tall ring of from one leg on a pair of pantyhose. “Queen-size” stockings recommended as being more comfortable.
- Tights should also work, as long as they offer a snug fit, says the researcher, who plans to include tights in future testing.
- The wearer puts the ring over their head like a headband, then pulls it down on top of the cloth mask, creating a tight fit to the face. This forces particles that might have otherwise gone around the loose edges of the mask and been inhaled to instead go through the mask, which can filter them out
- The research has not yet been peer-reviewed, although scientists who reviewed the study at NPRs request praised the study. Peer review matters in science, so we will keep watching.
- More research needs to be done, such as how many washings the delicate nylon hosiery can withstand before it loses effectiveness.
- A professional-grade surgical mask that blocked 75% of the particles on average. was used as a baseline measurement.
- The study was conducted on a variety of homemade cotten masks that were donated to Boston-area hospitals. Their effectiveness varied greatly, some blocking only 30% of the targeted particles.
- The masks that performed best in the testing were all made of a tightly woven cotton, the kind used for quilting, and they all contained a filter of some kind — either organic cotton batting or what’s known as interfacing, a lightweight, gauzy textile used to stiffen fabrics, such as shirt collars.
- Adding a sleeve of nylon increased the masks’ performance from 15%-50%.
Action update on making masks for health care facilities.
If you are donating masks to an specific institution – it is ESSENTIAL TO ASKwhat requirements they have. Material type? Nose wire? Filter pocket? Length of ties? Hospitals are rejecting all kinds of homemade PPE that don’t comply with their needs.
Ventura County needs handmade masks for front line professionals to cover their N95 masks. They have a very organized campaign for volunteer involvement and all donations must comply with specifications from their infection control staff. They have chosen this elastic-free mask type for its sturdy and comfortable design and ability to survive 5 months of daily washing in an autoclave, where elastic would melt. Filter pockets and nose wires are not accepted. They have also designed a gown that can be made by community volunteers. Click the links to sign up for the mask or gown brigade, OR BOTH!
Other hospitals need single-use masks to hand out to patients in waiting rooms to prevent the spread of COVID-19. That kind of mask may use elastic ear loops because they are easier for patients to use.
- If you have commercial masks and gloves you can donate to medical professionals – go here.
Masks for you, your friends and family – some caveats first.
- The CDC now recommends wearing them in public settings where other social distancing measures are difficult to maintain (e.g., grocery stores and pharmacies), especially in areas of significant community-based transmission.
- Note: none of these options featured below are as effective as commercial masks! They may even be counterproductive if not used with social distancing and good hygiene practices.
- There are no CDC ratings for homemade masks! If you are marketing them, DO NOT IMPLY that your masks are “CDC-approved” or that they achieve an “N95 rating.” This is false advertising and can create dangerous overconfidence in their users.
- Droplet protection only!: The CDC states that homemade masks can be used for droplet protection when there are no alternatives. “…homemade masks are not considered PPE (personal protective equipment), since their capability to protect HCP is unknown. …Homemade masks should ideally be used in combination with a face shield that covers the entire front (that extends to the chin or below) and sides of the face.”
- Some fabrics are better than others. The best masks were constructed of two layers of heavyweight “quilters cotton” with a thread count of at least 180, and had thicker and tighter weave.
- If you want to go deeper: A university study found that with certain common fabrics, (2) layers offered far less protection than (4) layers. (See “Deeper Dive” below- Missouri University study)
- However, a too-thick mask is hard to breathe through and causes moisture buildup and most home sewing machines can only handle a two layer mask. (See “Deeper Dive” below.)
- Here is a very specific discussion of fabric types. However, experts discuss T-shirt material as less effective due to its large holes and it is NOT acceptable for our local hospital masks! Thicker, heavier-weight T-shirts would probably be better filters.
- Nylons: Used as a additional pull-on shield which appears to materially increase particle blockage.
- Elastic: Many patterns call out for elastic, but this solution is only good for masks that are worn for a short time. Even for people who aren’t allergic to latex, elastic can break down the skin, causing the backs of ears to bleed. Open wounds are dangerous! If you are making a mask for a family member who needs to wear it all day, use a soft fabric for the ties.
- If you’re intending to use the innards of furnace filters in your mask, make sure they don’t contain fiberglass. Use non-filter fibers from HVAC filters as drop-ins for masks with inner pockets, or completely encase them in cotton fabric. (See “Deeper Dive” below.)
- Mask hygiene:
- Cloth face masks must be washed daily and handwashing hygiene must be maintained at all times.
- Disposable face masks have a very specific lifespan. While there are some with longer lifespans or that have replaceable filters, the most common face masks on the market are single use items. Each one of those is only good for a few hours and involve handwashing hygiene to be effective.
- Don’t make masks if you’re sick. Wash your own hands and wear your first sample mask.
- How to infect yourself with a mask: Putting masks on and taking them off is a great way to transfer germs. Take a minute to watch this video.
We will update as new information come in. We’ve included a variety to allow for skill sets and equipment, as not every one has a sewing machine. Online sources suggest twist ties and paper clips as “wires” for nose bridges and using rubber bands for elastic. Though nowhere near as effective as the nano-technology of commercial masks, the droplet protection afforded by cloth masks increases with the fineness of the cloth used, the number of layers, and attention to fit.
There are additional options for no-sew masks here.
Option 1 – the Bandana
Option 2 – the Bandana, CDC style
Needs a 20″ x 20″ bandana or cloth napkin, rubber bands or hair ties, and a coffee filter.
Option 3 – paper toweling /nose wire/face shield
This article and video is from Hong Kong. Paper is not the most effective choice. (See “Deeper Dive” below)
Option 4 – coffee filters/no pocket/nose wire
Option 5 – HEPA vacuum bag
Option 6 – CDC Quick Cut T-shirt Face covering
Option 1 – CDC version
Option 2 – Double-layer rectangle//nose wire/no pocket
This is a good video for beginning sewers.
Option 3 – Double or triple-layer rectangle//nose wire/no pocket
Faster version here.
Option4 – double-layer rectangle/pocket/no nose wire
Option 5 – double-layer rectangle /no pocket/no nose wire
This is from Deaconess Healthcare. They are asking for community volunteers to make them for their hospital. Video and instruction sheet are here. (if you don’t use elastic, make top ties at least 16″ long.
Providence St. Joseph Health in Renton, WA, is also asking for volunteers who have sewing machines to pick up kits to create 100 masks each for hospital visitors who may be exhibiting signs of coronavirus.
Option 6 – Shaped rectangle with bounded edges and integral ties, no pocket
Option 7 – double-layer rectangle/filter pocket/no nose wire/ties
This pattern and the method were recommended by the Belgian Federal Public Service for Public Health, based on a design byDr Chen Xiaoting, a Taiwanese anaesthetist
They suggest vacuum cleaner bags or carbon filters. The CDC recommends 8 layers of tshirt material which can be washed and reused.
Option 8 – double sided shaped, vertical seam/no nose wire/ no filter pocket
Quote from source: “You actually have to be a decent seamstress to sew these, between 30 and 45 minutes… These are DROPLET protection masks–very good for community spread prevention if used properly (ie the wearer avoids innoculating their face by adjusting the mask with unwashed hands), but not suitable for ICU use or for taking specimen
Option 9 – double-sided shaped, vertical seam, but with nose wire and filter pocket
Ignore her reference to medical professionals using both sides without sterilization. Written instructions here.
Option 10 – double-sided shaped, vertical seam, ties.
Video and instructions here
Option 11 – Double-layer rectangle/filter pocket/nose wire
- If you have skills to volunteer – website contact, connects to medical or government agencies – go here or go here.
- More designs and information here.
- Are you an organization in need of homemade masks? Fill out this form.
- Are you a medical professional in need of fabric face masks? Fill out this form or go here.
The options above are from the internet and physician friends. The stock of professional masks is dangerously low. Our medical professionals are worried that their need to stretch out the lifespan of protective equipment like masks and gloves could be putting patients at risk. They, along with their colleagues around the world, are searching for options and are sharing information on homemade solutions.
We’re not No. #1!
From this article
Why has it taken so long to ask the public to wear masks!
One of the offices Trump shut down, along with the White House Pandemic Response Team, was the White House Social and Behavioral Sciences Team, removing behavioral scientists who could have helped advise on exactly how to get people to actually follow instructions necessary to manage this crisis. Our current situation regarding mask usage is a case study in how NOT to communicate.
- Health experts, including the surgeon general of the United States, trying to preserving our inadequate supply of masks for health care workers, have stated that the public didn’t need masks. This contradiction confused ordinary listeners. How do these masks magically protect the wearers only and only if they work in a particular field?
- The public was also told that the effective masks, the N95, needed professional fitting to be useful. People have been repeatedly lectured on how to wash their hands but the message that they aren’t capable of learning to properly fit a mask hasn’t worked. The general public senses they are smarter than that.
- We are surrounded by images of other countries’ citizens wearing masks 24/7, along with World Health Organization (WHO) officials. Hong Kong health officials credit universal mask wearing as part of the solution and recommend universal mask wearing and Taiwan immediately ramped up mask production. We constantly compare our school results to those of these countries but don’t we trust them now?
- We are told to wear masks if we feel sick. However, we can also see reports that coronavirus can spread days before feeling any symptons. Even if one does have “symptoms”, should one wear a mask if it’s turns out to be just a cold or allergies when masks are in such low supply? Not being able to access tests for COVID-19 makes this a hard problem.
It’s no surprise that this whole campaign has backfired, as empty shelves and widespread price gouging will attest to. Supplies of a crucial type of respirator mask are dwindling fast, which could lead to multiple accidental infections of patients by health care professionals with no proper protective gear, or one trying to stretch the use of one beyond manufacturer recommendations.
Please leave the professional grade masks for the professionals!
Germany is joining South Korea and other countries in banning exports of medical masks and US stockpiles contain only 1% of the 3.5 billion masks that we are estimated to need. US mask makers and Chinese exporters cannot keep up with our demand. A medical supplier, Michael Einhorn said “We’re having to make tough decisions every day on who gets masks and who doesn’t. Do masks go to the suburban hospital or the 911 responders? It’s a huge responsibility, and we know we’re going to make some mistakes.”
“The one time you would want a mask is if you’re sick and you have to leave the house,” stated Dr. Perencevich. “If you have the flu or think you have COVID, that’s when you’d put on a mask to protect others. In your house, if you feel like you’re sick, you should wear a mask to protect your family members. If you are caring for someone with COVID in your home, it is wise to wear a mask when in close proximity to that person, who should also wear a mask, Dr. Perencevich said.” WHO added that there’s no evidence masks protect ordinary people going about their daily business. More important, handwashing and social distancing.
Why are N95 masks so effective?: N95 masks are tighter fitting and thicker than surgical masks. While surgical masks can block only large-particle droplets, N95 masks filter out 95 percent of all airborne particles when used correctly. The Centers for Disease Control and Prevention recommend that they be used only by people with infectious respiratory illness and health care workers who treat or otherwise come in contact with them. Even the best masks are effective only when used with proper hand-cleaning.
Why can’t we make more faster?: Masks are actually pretty complicated constructions and now there is now a global shortage of the “melt-blown” fabric required to make them. Melt-blown fabric is an extremely fine mesh of synthetic polymer fibers that forms the critical inner filtration layer of a mask, allowing the wearer to breath while reducing the inflow of possible infectious particles. “We’re talking about fibers where one filament has a diameter of less than one micron, so we are in the nano area,” said Markus Müller, the sales director at German company Reicofil, a major provider of melt-blown machine lines.
The machines that make the fabric costing upward of 3.8 million euros ($4.23 million) and are themselves are not easy to make because of the exacting precision required, says Müller. Reicofil’s Müller says he gets more than four dozen requests a day, mainly from China, to buy melt-blown fabric and production lines but has to turn nearly all of them away as making a single machine line takes at least five to six months.
China, the major manufacturer of the fabric, is retooling other types of factories to make masks, and is starting ten new melt-blown production lines. “Before the outbreak, the going price for one ton of melt-blown fabric in China was under 6,000 dollars a ton. But now, it’s about 60,000 dollars,” said a sales staff surnamed Guo at Xuzhong Guohong, a major supplier of melt-blown based in Hubei province, the center of virus outbreak in China. “The [shortage] issue is quite severe. Otherwise, why would the price be jacked up so high?”
Surgical masks offer less protection. They fit loosely around the nose and mouth, and fine, virus-laden airborne particles could be inhaled with unfiltered air around their edges. So a makeshift substitute like a bandanna or handkerchief that fits more loosely will filter out even fewer particles.
“Surgical masks provide less protection than N95 masks, and my guess is that bandannas would provide even less,” Rabinowitz said. Randomized studies that have tracked infection rates have found that surgical masks are just as effective as N95 masks at preventing the transmission of viruses, possibly because they prevent users from touching their face.
What about homemade masks? Would a bandana work?
- NOTHING WORKS WITHOUT ADEQUATE HAND WASHING! (WHO video)
- The NCBI states that homemade masks are not as effective as commercial face masks and should only be considered as a last resort to prevent droplet transmission from infected individuals, but it would be better than no protection.
- Dr. Arnold S. Monto of the University of Michigan’s Department of Epidemiology and School of Public Health said the loose-fitting surgical masks “are modestly effective — the problem is they are not nearly as effective as the N95 respirators.”
- Reports, including this one by the NCBI, with a summary here discourage their use based on their tendency towards increased risk of infection due to moisture retention, reuse of cloth masks and poor filtration.
- “One problem is that masks can become contaminated on the outside, and when you touch them, you can contaminate your hands,” – Dr. Peter Rabinowitz, a University of Washington professor
- The Director-General for the Department of Health of Thailand – “The droplet from coughing and sneezing is around five microns and we have tested already that cloth masks can protect against droplets bigger than one micron,” Panpimon said, adding that the masks needed to be washed daily.
If you want to make one, what material works best?
The Cambridge University experiments.
According to a studied performed at Cambridge University during the 2009 H1N1 flu pandemic, while surgical masks perform the best at capturing Bacillus atrophaeus bacteria (0.93-1.25 microns) and Bacteriophage MS virus (0.023 microns), vacuum cleaner bags, tea towels, and cotton T-shirts were not too far behind. The coronavirus is 0.1-0.2 microns, well within the range for the results of the tests.
The experimentThis study examined homemade masks as an alternative to commercial face masks. Several household materials were evaluated for the capacity to block bacterial and viral aerosols. Twenty-one healthy volunteers made their own face masks from cotton t-shirts; the masks were then tested for fit. The number of microorganisms isolated from coughs of healthy volunteers wearing their homemade mask, a surgical mask, or no mask was compared using several air-sampling techniques.(This information from smartairfilters.com)Surgical masks did best against 1-micron particles, stopping 97%. However, every material filtered out at least 50% of the particles.
But coronavirus is just 0.1 microns – ten times smaller. So the the scientists tested the materials against 0.02 micron Bacteriophage MS2 particles (5 times smaller than the coronavirus). Homemade masks caught 7% fewer virus particles than larger ones and all materials except the scarf stopped at least 50% of the virus particles.
Are more layers better?A little. The double-layer pillowcase captured 1% more particles, and the double-layer shirt captured just 2% more particles. Yet the extra dish cloth layer boosted performance by 14%. That boost made the tea towel as effective as the surgical mask. However, that increase came at the cost of breathability, which is important if the user doesn’t want to pass out. Vacuum bags and double-layer tea towels are really hard to breath through.
The winner(s)? The Cambridge study concluded that cotton t-shirts and pillow cases were the best choices with the following caveats:
- The median-fit factor of the homemade masks was one-half that of the surgical masks. Both masks significantly reduced the number of microorganisms expelled by volunteers, although the surgical mask was 3 times more effective in blocking transmission than the homemade mask.
- That a homemade mask should only be considered as a last resort to prevent droplet transmission from infected individuals, but it would be better than no protection. (Disaster Med Public Health Preparedness. 2013;0:1–6)
What about paper towels?
Not a good first choice…Tested against .3 microns, a single layer of paper towel captured 23% of particles and a double layer only 33%.
Missouri University of Science and Techology experiments
Yang Wang, an assistant professor of environmental engineering at Missouri University of Science and Technology, worked with his graduate students to study various combinations of layered materials — including both air filters and fabric. “You need something that is efficient for removing particles, but you also need to breathe,” said Dr. Wang, who last fall won an international award for aerosol research.
A typical surgical mask — made using a rectangular piece of pleated fabric with elastic ear loops — has a filtration efficiency ranging from 60 to 80% of particles as small as 0.3 microns, as opposed to a N95’s 95%.
Air Filters: Dr. Wang’s group tested two types of air filters, each with a MERV rating of 12 or higher, or a microparticle performance rating of 1900 or higher. NOTE: They can shed small particles that are dangerous to inhale and must be sandwiched between fabric layers.
- An allergy-reduction HVAC filterworked the best, capturing 89 percent of particles with one layer and 94 percent with two layers.
- A furnace filter captured 75 percent with two layers, but required six layers to achieve 95 percent.
Multiple fabric layer analysis: Dr. Wang’s group also found that when certain common fabrics were used, two layers offered far less protection than four layers. A 600 thread count pillow case captured just 22 percent of particles when doubled, but four layers captured nearly 60 percent. A thick woolen yarn scarf filtered 21 percent of particles in two layers, and 48.8 percent in four layers. A 100 percent cotton bandanna did the worst, capturing only 18.2 percent when doubled, and just 19.5 percent in four layers.
Coffee filter analysis: The group also tested Brew Rite and Natural Brew basket-style coffee filters, which, when stacked in three layers, showed 40 to 50 percent filtration efficiency — but they were less breathable than other options.
Vaccuum bags: In tests at Missouri University and University of Virginia, scientists found that vacuum bags removed between 60 percent and 87 percent of particles.
- Adding a nylon stocking layer could boost protection from cloth masks (npr)
- What you need to know about surgical masks, N95 respirators and coronavirus (knoxnews.com)
- What’s the best material for a mask? (NYTimes)
- Testing the efficacy of Homemade masks: Would they protct in an influenza pandemic? (researchgate.net)
- What is your furnace air filter made of? (brennanshvac.com)
- A cluster randomised trial of cloth masks compared with medical masks in healthcare workers (ncbi.nlm.nih.gov)
- We don’t have enough masks (atlantic)
- Pandemic planning: Recommended Guidance for Extended Use and Limited Reuse of N95 Filtering Facepiece Respirators in Healthcare Settings (CDC)
- Strategies for Optimizing the Supply of Facemasks (CDC)
- Trump administration scrambles to offer guidance on what to do if hospitals run out of basic supplies for coronavirus (wapo)
- Direct Relief delivers critical medical supplies to Cottage, Public Health Departments (KEYT)
- Calling All People Who Sew And Make: You Can Help Make Masks For 2020 Healthcare Worker PPE Shortage (forbes)
- What are the best materials for making a mask (smartairfilters.com)
- Can a face mask protect me from coronavirus? Covid-19 myths busted (guardian)
- OK, she’s totally wrong about the spread of the coronavirus, and she probably wishes she could remove the front 30 seconds, but good information on difference between mask types.
Information about Sewing Masks in the time of COVID-19 (equilter.com)
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