The purpose of this project is to demonstrate an optimal method for how to produce up to 20 masks per hour of Consistent quality, with a tight fit and performance equal to a top quality surgeons mask. It is made from commonly available materials and requires marginal skills.

1. Please start with watching the video above (1:31 min or click this link to open in a new window)

2. Download and Print the Sewing Jig and Cutting Pattern on A4 card, 160-250gsm
Regular size: Download
Small / Youth: (Soon. Print the Regular@90% for now)
Children ~5-12 YRS: Download

3. Have a look at this video (5:40 min) for help with how to assemble and use the Sewing Jig. Place the fabric in the jig with the Bag Outside facing up (towards you - The Bag Inside will become the Mask Outside.)

4. Source materials. In addition to the filter fabric as discussed below, you also need:

# Metal nose clip. This is the 2nd most important part of your mask. The metal strip should be stiff enough to not give but soft enough to not cause pain when pressed to shape over the nose. Suggestions - Aluminium on roll ~0.5mmx5mm, Single core copper wire, tin cans cut to strips works great (with a pair of robust kitchen scissors).. Pipe cleaners folded double as a last resort (they are a little too flimsy)

# Elastic ribbon, use a flat type ~5mm width elastic, or possibly a wider cotton ribbon (if you prefer the mask tied behind the head). Avoid silicon/rubber quality elastics as they get caught by the needle and will slow down production.

5. Do not give masks away unless sterilized. Alternatively, if 'just' distributing to friends and family: Simply bag and seal the masks and keep them aside for minimum a week, in room temperature, before handing them out. The SARS-CoV-2 virus will not survive that long. (If anyone has information saying otherwise, please do contact me asap)


WHY PRODUCE SO MANY?
You need a number of masks yourself so you can rotate them. (By quarantining worn masks for at least a week before re-use). Then, they will have to be replaced when getting lost or tatty. Then those you care for need masks.. Then, they need to rotate and replace...

FILTER RATING VS. DESIGN
The mask presented here is assumed as effective, in terms of filtration ability, as any high quality Surgeons Masks. I read the report from Cambridge University (ref, p2) as HEPA rated vacuum bags are optimal for making surgeons masks given a) you find, unlike them, a hepa material that allows enough air through and b) it, unlike theirs, is well designed (providing a tight fit).

Why the surgical mask design? They are effective, quick and easy to make. By numbers the FFP2/FFP3 (N95/N99) are superior to Surgeons Masks (ref) but in reality, the gain in terms of ability to keep you safe seems somewhat marginal (ref, Closing statement / Comments: " In routine health care settings, particularly where the availability of N95 respirators is limited, surgical masks appear to be noninferior to N95 respirators for protecting health care workers against influenza.")
The question is therefore - Should you attempt making a limited number of FFP2 equivalent masks, or a sufficient quantity of high quality surgeons masks?

Why not a mask with a hepa pad/pocket? There are several issues with this type of design. Most importantly, a good portion of the inhaled air would bypass the pad and enter through the surrounding material. The entire mask must be made from Hepa filter material so there are no false entry. Also, a hepa filter is 'tuff to breathe through. The smaller the pad the harder it is to breathe. Hence the pad should be as large as possible. Ie. again, the entire mask should be made out of hepa material. Then, contamination.. You can not wear the same mask every day. The mask must be sterilized after each use, or it must rest for a week before re-use. It isn't enough just replacing the pad. The list of issues does not stop there. A semi disposable surgical mask is as I see it the only viable route.

Research shows masks do not protect children well (ref to be added). Many factors come to play here, but the most obvious thing we can do about it is to provide the children with comfortable masks that fit them well. A mask adapted to children 5-12 is therefore available below.

SOURCING A SUITABLE MATERIAL
My choice of filter fabric is the "Numatic Hepaflo" vacuum bag. It consists of 3 layers of SMS (spun-melt-spun) Polypropylene/PP, just like the material used in most surgical masks. Its technical documentation indicates an ability to stop 80% of dry 0.3 Micron particles - i.e. it is a H10 class HEPA filter, equivalent (if not identical) to the filtering ability of the highest quality surgeons masks. The fabric is neat and thin and easy to work with. You can of course use other hepa rated vacuum bags from other brands. In addition, there are other fabrics you can use, Cotton, tea towels. Please have a look at a few options (Table 1). Unfortunately, most alternatives are inferior to a H10 or upwards HEPA material.

NB! Paper quality bags are NOT suitable for this project.

Dry dust filtering ability is graded in classes (ref):
G (G1-G4),M (M5-M6) and F (F7-F9) class are not suitable for this project.
H10 (EPA or 'Semi HEPA' E10) is ~FFP1 equivalent and optimal for this project.
H11 and H12 (EPA or 'Semi HEPA' E11/E12) are ~FFP2/N95 equivalent may be usable but please test for sufficient airflow as suggested below.
H13 and H14 (>99,9% @0.3micron are true HEPA and comparable to FFP3/N99/N100) Airflow likely too restricted for this project.
U15-U17 (ULPA) Ultra high filtering ability but again, airflow is insufficient.

The best balance between filtering ability and avoiding issues with airflow seems to be found at about >= H10(E10) and <=H11(E11).

Airflow test. Breathe calmly through the fabric with your mouth wide open while walking at a slow pace up and down a stairway a few times. If you can resist the urge to have a fresh whiff of air then there is sufficient airflow through. (Breathing will be much (~proportionally) easier through the larger fabric used in the finished mask)

If the filter material you've obtained failed 'the test' - consider 'A Doctor Explains How to..' found in the links below. Their design allows the use of materials with further reduced airflow. It is a very good option if quantity is not your concern.

Also I - Safety: Avoid products labelled 'odourless', 'odour control' etc. Chemicals and possibly perfume have been added to absorb smell and/or trap moisture.

Also II - "Fibreglass..?": Fibreglass can be found in HEPA filter cartridges used in ventilation, but apples are being confused with pears. Fabric vacuum filter bags are made from thermoplastics not glass.. You can test your material to be sure it is indeed a thermoplastic by simply setting fire to a little sample. Hold with pliers. If it burns and drips like candle wax, and leaves no 'bush' of brittle fibres behind, then you know it is indeed a thermoplastic. Alternatively, try this method, it's less messy but requires a hot air gun.

Also III - Airflow/direction: A vacuum bags filtration happens in 2 or more stages. The bags inmost layer is a course filter, the middle layers are the finer filters. The bags outer layer just prevents the bag from ripping. Therefore, the bags inmost layer should face outwards when worn as a mask. This ensures inhaled air is first course filtered before fine filtered (and it keeps fibres from tickling your face :-)). If the bags inside is 'ugly', consider sandwiching with a more representable fabric. (It must be very thin (and breathable!) or the added thickness will cause problems with the Jig)

STERILIZING
Preheat your oven to 70 deg Celsius (that's 158F). Use an oven thermometer! Make sure the temperature has stabilized before proceeding. Seal masks individually or in batches in air tight (zip lock) plastic bags. Wrap the zip lock bags inside a few kitchen towels to protect them from direct radiation from the ovens heating elements - and bake in a tray in the low/middle for an hour. NB! Do not use the hot air/fan function.

#The Stanford report states a home oven should not be used for re-sterilization of used masks due to the risk of bringing contaminaton home. There should be no reason why a home oven cannot be used to sterilize masks produced by yourself. (ref, p2)

#Zip lock bags: Any size from 11x18CM (4.5"x 7") and up. Alternatively, use freezer bags (tie a knot to seal..)

PERSONAL REMARK To sum it up ..? I use this mask myself every day. So does my kids and my wife. In the shops, around town. But, a surgical mask may not the best choice for situations where strangers literally sit on your lap, like when flying. I will be making myself a handful of these if forced to travel.

CORRECT USE..
- Wash your hands before putting on or removing your mask. Wash once again after the mask is removed. Never touch your face (or mask) while wearing a mask.
- Do not put a recently worn mask back on. Make yourself a number of masks, rotate and let them rest 1 week before re-use.
- Walk slowly, breathe calmly. Keep a distance.. Take your time....

PLEASE HELP HELPING
Please share the link to this page
Or use this link if you wish to link directly to the video on Youtube.

 

With Love from
St Esteve de Palautordera
Spain


SH
Industrial Designer MA
Please click here for email
+34 622 13 7743
+47 46 298 131


REVISION HISTORY
20200517 - Updated templates will be uploaded soon. Minor changes.
20200429 - Added the how-to video
20200425 - Children's mask improved
20200423 - Edited the Youtube video
20200414 - Valuable feedback and user testing. Thanks Axel.
20200413 - Installed Matomo
20200412 - Mask for children 5-12 YRS published. Added note re. fibreglass and to avoid "odourless" bags.
20200411 - Rewrite and typos
20200410 - Published for initial review
20200408 - 1st Draft

REFERENCES

Numatic Hepaflo datasheet (or here)

HEPA / Filter classification, Wikipedia

Surgical Mask vs N95 Respirator for Preventing Influenza Among Health Care Workers

Particle Size-Selective Assessment of Protection of European Standard FFP Respirators and Surgical Masks against Particles-Tested with Human Subjects

Testing the Efficacy of Homemade Masks: Would They Protect in an Influenza Pandemic? |

Disaster Medicine and Public Health Preparedness | Cambridge Core

N95 vs FFP3 & FFP2 masks - what's the difference?

A Doctor Explains How to Make the Safest Face Mask - YouTube

https://stanfordmedicine.app.box.com/v/covid19-PPE-1-1

Fibreglass in vacuum bags?


TODO
- The smaller size will be posted soon. (Please scale the Regular size mask down for now. print at ~90 %)
- Translate website and content to Spanish and French. Soon.
- A tips and tricks / FAQ section is needed
- LAB TESTING, Can "someone with a lab" please come forward and offer to do a head to head comparison of our design to a standard surgeons mask. An independent test report will provide hospitals, schools etc around the world the evidence and courage they need to produce this mask. please contact me


WHY
- are you doing this?
Being an industrial designer.. I couldn't find a mask that provided both sufficient protection and was quick enough to produce in 100's. I therefore developed this mask / method for myself and my family. I documented the process for family and friends, far and near, to be able to replicate while we wait for amazon to stock back up.. So, here it is, with the best intentions, on the house :-)

DISCLAIMER - All content linked or published on this webpage is designed and developed by the owners of this website. No content should be copied, kept or distributed from elsewhere without our consent. Please respect intellectual property. This project is under constant and rapid development - changes made here can contain vital updates important to people and their health. Please link to this page instead of directly to what may be outdated content on this page. Hypothetical revenue generated from the youtube content, if any, will be donated to local healthcare. Profit is not the drive here.

GDPR - Youtube drops a 'doubleclick' cookie on you because of the embedded video. This site also uses a cookie (Matomo Open Source Analytics). I collect out of curiosity statistics to know where visitors connect from. Personal data are anonymized when collected and stored anonymized in our database. It will be interesting to see which parts of the world makes use of this. The stat data are kept locally and will never be shared. All stats will be flushed once this project is no longer required (thank you for understanding)

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