Since June, the World Health Organization (WHO) has recommended 3 layer face masks.
The ideal mask has a water-resistant outer layer, a polypropylene middle layer (like interfacing), and a water-absorbent inner layer to absorb your droplets.
To make a 3 layer mask, you can sew a normal 2 layer one and use a filter insert as your 3rd layer, or you can sew 3 permanent layers.
WHO doesn’t recommend a specific sewing pattern, but they do give guidelines on what mask designs are best. The best DIY masks are close-fitting around the nose, cheeks, and chin, to stop your droplets escaping through gaps. They have a nose wire and 3 layers of fabric.
Contents list:
- What fabric should be used for each layer?
- What mask design does WHO recommend?
- 3 layer face mask patterns with little gaping
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 🙂
Related post: Fusible Interfacing for Face Masks: Good Filter? Safe? Breathable?
Related post:
What fabric to use for 3 layer face masks
- Outer layer (exposed to the world): water-resistant material. WHO suggests polypropylene or polyester.
- Middle layer: a synthetic, non-woven, water-resistant material. They suggest polypropylene or interfacing. If unavailable, use cotton.
- Inner layer (that touches your face): a water-absorbent fabric so it absorbs your droplets. WHO suggests cotton.
Outer layer
WHO recommends “…an outermost layer made of hydrophobic material (e.g., polypropylene, polyester, or their blends) which may limit external contamination from penetration through to the wearer’s nose and mouth…” (source, page 10).
Hydrophobic means “the fabric will repel droplets and moisture” (source).
The challenge is many polyesters aren’t breathable (it depends on how the fabric is woven). The best way to figure this out is to order samples, cover your nose/mouth with it, and see if you can breathe.
Here are water-resistant fabrics you can sample from Fabric.com (USA) and My Fabrics UK.
Don’t use waxed/coated fabric
WHO says “coating the fabric with compounds like wax may increase the barrier and render the mask fluid resistant; however, such coatings may inadvertently completely block the pores and make the mask difficult to breathe through.
In addition to decreased breathability unfiltered air may more likely escape the sides of the mask upon exhalation. Coating is therefore not recommended.” (source, page 10).
I think WHO is mostly right. Generally, waxed fabric used in waterproof coats and bags is hard to breathe through.
However, there are exceptions. I found some light to medium weight 100% cotton in my fabric stash which had a thin water-resistant coating. I could breathe through 1 layer of it, and water beaded up and rolled off when I tested its water resistance.
So these materials do exist. Unfortunately, I’m struggling to find a similar fabric online.
It’s impossible to know if a fabric truly is breathable unless you buy samples and test it.
Here are water-resistant fabrics you can sample from Fabric.com (USA) and My Fabrics UK.
Middle layer
In a video, WHO explains the middle layer should “act as a filter”.
They recommend that you bin the filter after each use, unless it’s sewn into the mask permanently.
WHO gives 2 options for the middle layer:
- A synthetic, non-woven, water-resistant material like polypropylene. They gave interfacing as an example of polypropylene.
- Or cotton.
Here’s a direct quote: “…a middle hydrophobic layer of synthetic non-woven material such as polyproplylene or a cotton layer which may enhance filtration or retain droplets.” (source, page 10). Hydrophobic means “the fabric will repel droplets and moisture” (source).
They used interfacing as an example of polypropylene on page 9 of their official guidance:
I’m assuming this is craft interfacing, used in textiles and clothing. I can’t be 100% sure as they don’t go into details. I’m also not sure that craft interfacing is water-resistant.
In terms of what weight to choose, in their videos they show a very lightweight material as their example of a filter insert.
For US citizens, Fabric.com has a big range of interfacing you can choose from. For UK citizens, Minerva Crafts and My Fabrics UK sell interfacing.
Note: if you include interfacing in your mask, be careful how you wash it. It’s a non-woven material, so it doesn’t like agitation. I have a separate post on how to wash face masks according to authorities like WHO.
If you can’t find polypropylene or interfacing for the middle filter layer, cotton is OK.
It can help absorb your droplets and slightly increase the filtration ability of the mask. WHO acknowledges that “commercial cotton fabric masks are in general very breathable but offer lower filtration.” (source, page 9).
Inner layer
This is the layer that touches your face.
WHO recommends “…hydrophilic material (e.g. cotton or cotton blends)…” for this layer (source, page 10). In a video, they explain hydrophilic means the fabric “will easily absorb droplets from your exhaled breath“.
They recommend using white cotton, so it’s easy to know when the mask is wet or soiled (source).
You can find cotton from these large online stores: Fabric.com (USA), Minerva Crafts (UK), and My Fabrics (UK).
Use tightly woven fabric
WHO warns “very porous materials, such as gauze, even with multiple layers will not provide sufficient filtration…” (source, page 9).
“It is important to note that with more tightly woven materials, as the number of layers increases, the breathability may be reduced. A quick check for breathability may be performed by attempting to breathe, through the mouth, and through the multiple layers.” (source, page 9 & 10).
Use fabrics that can be washed at high heat
WHO says “fabrics that can support high temperatures (60° or more) are preferable.” (source, page 11).
“The combination of non-woven PP [polypropylene] spunbond and cotton can tolerate high temperatures; masks made of these combinations may be steamed or boiled.” (source, page 10).
Whatever washing method you choose, make sure you pre-wash the fabric at that temperature. This will stop your masks from shrinking when laundered.
Don’t use stretchy fabric
WHO says “it is preferable not to select elastic material for making masks; during wear, the mask material may be stretched over the face, resulting in increased pore size and lower filtration efficiency throughout use.
Also, elastic materials may degrade over time and are sensitive to washing at high temperatures.” (source, page 9).
Page 11 confirms “avoid stretchy material for making masks as they provide lower filtration efficiency during use and are sensitive to washing at high temperatures.”
On the other hand, they have made videos where they recommend using stretchy t-shirt material.
My understanding of this mixed messaging is that we should only use stretchy fabrics if that’s all we have. Ideally, we need to use non-stretch fabrics.
What mask design does WHO recommend?
I have not seen them endorse a specific face mask pattern. They generally recommend designs that create a leak-proof seal around the nose and mouth.
Here’s a direct quote: “Mask shapes include flat-fold or duckbill and are designed to fit closely over the nose, cheeks and chin of the wearer.
When the edges of the mask are not close to the face and shift, for example, when speaking, internal/external air penetrates through the edges of the mask rather than being filtered through the fabric. Leaks where unfiltered air moves in and out of the mask may be attributed to the size and shape of the mask.” (source, page 10).
In videos, they recommend creating a 2 layer face mask with a filter pocket, so your filter insert becomes the 3rd layer. Or you can create a mask with 3 permanent layers.
In one video, WHO recommends using a nose bridge in your mask so that it fits your nose and cheeks better. They suggest using the plastic twist ties found on grocery store packaging.
Others suggest wire or double-sided skin tape to create a seal.
The University of Florida Health recommends 16-gauge craft wire (not aluminum, as it’s too soft). 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. You can find wire, pliers, and cutters from Amazon.
Unity Point Health recommends double-sided skin tape to create a seal around the nose and mouth. It’s available on Amazon.
How to make a 3 layer face mask + patterns
You have 2 options:
- Create a normal 2 layer face mask with a filter pocket. Whatever you place inside the pocket will be the 3rd layer.
- Create a mask with 3 permanent layers.
As mentioned above, I haven’t seen WHO endorse a specific sewing pattern. I’m going to share mask designs that fit closely around the nose, cheeks, and chin, as they suggest.
One source I used was a video by healthcare worker and Youtuber Sewstine. She did an experiment to find the best fitting DIY face mask. She made 4 face masks and put them through a hospital fit test.
A fit test checks whether a mask fits perfectly with no air leaks. Only 1 mask passed the fit test for her and her 3 female colleagues.
She filmed the whole process for Youtube. I’ll be summarising what she said and which pattern won.
An important thing to know is just because a mask passed a fit test for someone else, it doesn’t mean it would pass for you. Everyone’s face shape is unique, so you’ll probably need to make adjustments to remove gaps in your mask.
Rounded face mask pattern with a ‘beak’ (UF Health)
The University of Florida Health (UF Health) created this pattern. The design includes:
- A nose wire.
- Ties around the head.
- Lots of space in front of the mouth. The shape reminds me of a beak.
This was fit-tested by UF Health on 20+ volunteers (source). It was fit-tested again by medical worker and Youtuber Sewstine. Her hospital tested it on 3 women and it passed, but only with skin tape where there was gaping.
Download the pattern for free from the university website.
Here’s their sewing tutorial:
The problem with this mask is that it’s designed for a specialist material called Halyard H600. It doesn’t fray, so the sewing tutorial leaves the edges raw. This wouldn’t work for normal woven fabric, so you’ll need to make changes to the instructions yourself.
Similar patterns with easier instructions
This style with a “beak” at the front reminds me of the Jesse mask. This mask is designed for normal woven fabric, so you can follow the instructions without making changes.
Here’s a video sewing tutorial (the actual sewing starts at 23:18):
Duckbill face mask pattern
This is one of the styles WHO suggested in their official documents (source, page 10).
Youtuber and medical worker, Sewstine, sewed and fit-tested a duckbill mask. She drafted the sewing pattern herself, so it’s not publicly available.
She liked the fit of the mask, but it failed hospital fit-testing, even with skin tape. She did think that with some modifications it might have passed.
If you want to make your own version, here’s a similar duckbill pattern and tutorial that a physician made. It includes 3 permanent layers, a nose wire, and elastic around the head.
Pleated face mask pattern
Sewstine tested the pleated mask pattern by the University of Florida Health (UF Health).
This pattern includes:
- A nose wire
- Ties around the head
- Pleats
Sewstine’s hospital fit-tested this on 4 people and it failed, even with a nose wire and tape on the sides to reduce gaping.
However, the pattern designer, UF Health, did their own fit tests on 20+ volunteers (source). So it may or may not work for you.
Download the pattern for free from the university website.
Here’s their sewing tutorial:
The problem with this mask is that it’s designed for a specialist material called Halyard H600. It doesn’t fray, so the sewing tutorial leaves the edges raw. This wouldn’t work for normal woven fabric, so you’ll need to make changes to the instructions yourself.
Similar patterns with easier sewing instructions:
Selsey Medical Practice made a pleated mask pattern with a nose wire, 3 layers, and elastic ear hooks. The only change I would make is using DIY adjustable ear loops instead.
Healthcare provider Kaiser Permanente has a pleated mask pattern with ties and 2 layers. There’s no nose wire.
Olson mask by Instructables
Sewstine liked the design and fit of this mask, she said it felt the most comfortable, but it failed the hospital fit test even with tape.
The sewing pattern and instructions are on the Instructables website.
Similar patterns:
A similar mask was designed by healthcare provider Unity Point Health. Their version includes 3 permanent layers, a filter pocket, and elastic ear hooks.
Here’s their video sewing tutorial:
Related post: Fusible Interfacing for Face Masks: Good Filter? Safe? Breathable?
Related post:
Related post: 41 Mask Patterns Approved by 64 Hospitals (+ PDF Printables)
Related post:
Sources
Sewstine’s full comparison video of all 4 mask designs:
World Health Organization. ‘When and how to use masks’. [online] Available at: https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public/when-and-how-to-use-masks [Last updated: 5 Aug 2020]
World Health Organization. ‘Advice on the use of masks…’. [online] Available at: https://www.who.int/publications/i/item/advice-on-the-use-of-masks-in-the-community-during-home-care-and-in-healthcare-settings-in-the-context-of-the-novel-coronavirus-(2019-ncov)-outbreak [published: 5 June 2020]
Sewstine. ‘I sewed and fit tested four different face masks…’. [online] Available at: https://www.youtube.com/watch?v=DZBbkn-g-vE&feature=emb_title [published: 1 April 2020]
