Man. it's been a trip. I got married, got sick, and now COVID-19 is at all of our doors. With the insane shortage of masks available combined with being at risk myself due to my health history and my MIL working at the local hospital, it was only a matter of time before I used my craftiness to make my own. I decided it was time to do some serious research, which means this is going to be a long post, so buckle up!
Why Homemade Masks?
The CDC is recommending cloth masks as a means to help flatten the curve,. They are not 100% effective and depending on your material types, efficacy ranges are drastic. However, any barrier covering your nose & mouth helps reduce your chances of catching the virus. The more you can seal the mask, the more effective it will be. Adjustable nose bridges are a great idea & super helpful, as well as securing straps that keep the mask tight against the face.
Masks also help prevent touching your own face. The virus can survive for extended periods of time on inorganic matter. Wearing a mask helps stop you from putting your hands near your nose or moth, which also helps reduce your risk of exposure.
It is important to know that homemade masks are not medical grade, nor are they a single solution. Primarily they prevent the wearer from spreading disease, and not as much from catching disease. You still need to be diligent about hand washing, social distancing (6 feet or 3 meters apart), and shelter-in-place. It is also important to note that while gloves seem like a great idea, for the general public they aren't doing too much. That's not to say you shouldn't use them, but be aware that just like masks, gloves should be reserved for the medical field (and gloves are useful for those in other essential industries). Frequent washing of surfaces will help minimize the need for gloves as well.
But I've Heard Cloth Masks are Harmful.
This is not true. They are not as effective as the manufactured surgical masks and respirators, but any barrier is better than no barrier. The problem with people wearing cloth masks is a false sense of security, which honestly applies regardless of which type of mask you wear. When the general populous wears masks in a pandemic situation, they feel a false sense of security and aren't as diligent about other preventative methods.
What Materials Should I Use?
If you want to increase your personal protection from wearing a mask, there are a lot of extras you can add. From the fabric you choose to additional filters, you have a wide range of possibilities with an equally wide range of protection. But remember, any protection is better than none at this point.
Cotton seems to be the general consensus, which seems ironic since it is a woven fabric. Denser fabrics that are 600-count and higher are considered a pretty good choice, and flannel can be a great lining since it is softer on your face. 600-count cotton fabric blocks 22% of airborne particles with 2 layers and about 60% with 4 layers. High-quality quilting cotton can block 70-79% of airborne particles.
Halyard H600 is used by hospitals as a bacterial filtration system when cleaning surgical equipment. It is washable and relatively affordable. This recommendation originally came from the University of Florida, and hospitals can actually put masks made from this material into their autoclave for sterilization.
Oly-Fun fabric is similar to surgical sheeting, which will help keep things sterile & prevent germs. It should be sandwiched between 2 layers of cotton. If you do not have access to Oly-Fun, you can cut up reusable grocery bags or non-woven interfacing that is not dissolvable in water. Fusible interfacing is also ok. Some are concerned this impacts breathability, but if you use lightweight interfacing it should be fine. The downside of fusible may be some lingering scent from the "glue," which can be resolved with a few washes. It's recommended to use 2 layers of Oly-Fun or interfacing.
The CDC shared a "light test" to determine how impactful your fabric will be. Basically, hold it up to a light and if you can see the light through it, or more specifically if you can make out the fibers, it's not a great choice. However, even scarves & bandanas which fail this test are better than nothing!
Filter Options
Coffee Filters are probably the easiest, most affordable filter option. 3 layers blocks 40-50% of airborne particles, The downside to them is that they are not as breathable as other filters.
Surgical Masks (the pleated, disposable ones) have an effective filtration range of 60-89% of airborne particles. These are designed as single-use masks and are compromised once they become damp, but many professionals are being forced to reuse them throughout the day, or even week! However, they can be used as a filter in a sewn mask, to help prolong their lifespan, as the fabric will act as a barrier for water particles from coughing and sneezing.
N-95 Respirator Masks filter out up to 95% of particles as small as 0.3 micron; or overall 90% of airborne particles (approximately). While this isn't exactly a filtration option for homemade masks, covers can be made to extend the life of these respirators.
PM2.5 Carbon Filters will filter out 2.5 microns. These filters are limited use, usually for 48-72 hours, but you can usually find a pack for a decent price. Given the circumstances we are currently dealing with, you may even be able to stretch it to 5-7 days if necessary (it will still work better than no filter at all).
HEPA Air Filters (and vacuum bags) catch up to 99% of particles as small as 0.01 micron, and are
99.97% effective against particles as small as 0.3 micron. However in practical mask tests, vacuum bags tested closer to 60-87% blockage. You will also want to pay attention to whether the filters/bags you are looking at use fiberglass, as that is dangerous to breathe in and additional precautions need to be taken. As an alternative, you can look into 0.5mm HEPA H11 Polyester Meltblown Non-Woven Fabric HDF90-H1, which is polypropylene/plastic and not fiberglass.
Dr. Yan Wan, assistant professor of environmental engineering and Missouri University of Science & Technology, tested some filters you would typically use in your home. Allergy-reduction HVAC filters block 89% of particles, or up to 94% if using 2 layers. Furnace filters block 75% with 2 layers, but you can get up to 95% with 6 layers. If you choose either option, make sure to sandwich between cotton fabric to prevent shedding of the filter materials.
If doing your own research, Wang recommends looking for a MERV rating of 12+ or microparticle performance rating of 1900+.
COVID-19 Size
The novel coronavirus 2019 (2019-nCoV), now referred to as SARS-CoV-2, is estimated to be about 0.125 microns. However, it usually travels in an aerosolized form from coughing and sneezing, which means we are aiming to protect against 0.5-3 micron. Because of this, the medical standard is aimed at capturing particles around 0.3 micron. Also, smaller particles tend to move erratically, making them easier to catch.
Which Patterns Are Best?
There's a lot of debate and personal opinion regarding patterns. Honestly, I say choose whatever fits you best & most comfortably. Patterns that include or allow for the addition of an adjustable nose bridge are better.
The Pleated Mask is one of the easiest and most popular, but not the best sealing. This link is for the Deaconess pattern, but they all follow the same gist. You can do 4 or 5 pleats instead of 3; you can iron/press in your pleats; you can even seam in your pleats (be careful if you try this); you can even add in a filter pocket. The advantage to these masks is that the pleats and large fabric size make them easily adjustable, but I find most patterns often had such a wide side that it will pucker.
The Duckbill Mask is one of the more popular styles among medical professionals. Named for its rather obvious appearance, the advantage of this design is how easily it fits a variety of sizes. Most patterns I've been seeing lately are creating this mask out of household filters or vacuum bags, but be aware of the risk of using those materials.
The Ninja Mask is a design I've seen recommended by nurses, and it seems to be one of the most popular in general. It's a more tailored fit with good coverage.
The Chin Strap Mask is one of my favorite, design-wise. I like that the strap goes under your chin for maximum seal, and I like the tailored fit around the nose & eyes. It feels like a step up from the Ninja Mask.
Florida Univerity Prototype #2 has a great seal and comes highly recommended. It was designed by pros and has passed a fit test to ensure maximum protection. FU used Halyard 600 in both of their designs, so be aware how material choice may alter the efficacy of this design.
The Nose Mask is an N-95 copy-cat. I think this pattern is pretty ingenious & appears to offer a great seal. The downfall being, as mentioned above, the shedding of material. The filters used to create the masks in this tutorial use fiberglass which is dangerous to inhale. This mask would need to be sandwiched between some cotton fabric.
The 3D / Box Mask is my favorite. It has good coverage and adjustability. The basic version can be made out of a single rectangle of fabric, or if you are like me, you can beef it up with some interfacing and a separate liner that features a filter pocket. It feels like it has a good seal, and offers adjustability for the chin and nose. The narrow sides help prevent puckering when wearing.
No matter which pattern you choose, make sure to prewash your fabrics.
No-Sew Options
Not everyone is a sewer, and to be honest finding materials is getting harder by the day! There is an origami version using vacuum bags, as well as one using just a piece of fabric & rubber bands (you can use things like a scarf, t-shirt, bandanna, or small cloth/towel).
Ties or Straps?
Many patterns recommend ties for comfort, but there are some cons. In the medical field, ties are a hindrance as they take time to adjust. Often, medical professionals don't have the luxury of time, so the quicker they can get a mask on, the better. Ties also risk loosening over time, which again is of concern for medical professionals.
On the other hand, elastic straps can get very uncomfortable over time. Ties are a nice alternative to this, as they can be made with a softer material (knit/T-shirt material is a good suggestion).
I've actually been using nylon hair ties & headbands in my masks. They offer stretch like elastic, but are a bit softer on the ears. Wearing glasses, I find that pretty important, and I'm sure for people wearing masks hours at a time this will be appreciated. They do stretch out a bit, but you can stretch the fabric perpendicular to the length and they shrink up quite a bit. They will also shrink in the wash, so if you aren't wearing the same mask day after day without washing (which you shouldn't be anyway!), this will primarily self-correct.
Tips & Tricks
Regardless of which pattern you choose, it's been highly recommended to make the inside & outside a different color, even if your pattern doesn't really lend to wearing either way. This is a quick & easy visual for the wearer which side is "contaminated."
If sewing in your elastic or ties, bringing them in a centimeter or so from top & bottom helps create a more secure fit. This helps keep the side flat against the cheek instead of puckering (which reduces the seal & therefore efficacy).
Add an adjustable nose bridge! This is pretty critical to creating a good seal. You can easily test the seal by putting on a pair of glasses & seeing if they fog up. If your glasses fog up, the seal is not good. You can sew in a 3-inch 16g wire strip directly into the seams, attach a sleeve, tie it on, or even glue it in. You have so many options available to you, with the most accessible recommendations being pipe cleaners and twist ties. Personally, I have preferred using flat jewelry wire.
Make sure your elastic is even on both sides. You want the mask sitting centered and with a proper seal. You can also consider longer elastic and some adjusters, which allows the wearer to adjust to their comfort and corrects for uneven elastic.
Cotton thread is also highly recommended as it can hold up to high heats for cleaning (in the wash or an autoclave).
Use clips instead of pins. The idea of the masks is to filter out dangerous particles, so the fewer holes you create in the fabric, the more effective your masks will be.
Reinforce your stitches! Make sure you have strong stitches where your elastic or ties are attached (or if you are slipping through a channel, make sure the channel is reinforced). You also want to make sure the nose piece is well secured since it is such an integral part of an effective mask.
Add a valve if your mask feels too stuffy. I do not mean go out and make your own valve though, but RZ Masks was where I got this idea. The one-way valve doesn't let air in, but lets your hot breath out. Given the current situation, this is not ideal, but if you make your own masks for other applications in the future, the valve is pretty nifty.
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