Materials Guide




Recommended Fabrics

  • 100% Cotton Woven (bedsheets, towelling, quilter's cotton/fat quarters, broadcloth, flannel)​

  • 100% Cotton Jersey (T-shirt fabric)


  • Pellon Light or Medium-weight sew-in interfacing can be added to improve sturdiness and filtration. (Do not use fusible interfacing, which will break down during sterilization)
  • The tighter the weave and higher the thread-count, the better the filtration. Hold fabric up to the light to see how much light penetrates, double up if needed.
  • Comfort and breathability are also top priority. Stiff fabrics like canvas or duck might injure skin across 12-hour nursing shifts. Impermeable/synthetic fabrics like cordura might accumulate moisture and decrease airflow.
  • Always pre-shrink cotton fabrics by washing hot and machine drying if possible. 
  • Cotton blends are also acceptable as long as they can be washed with hot water. Boiling the fabric is a good test!
  • Used fabrics are OK so long as they are freshly laundered
  • Two distinct colors on top/bottom layer allow the wearer to easily know what side is inside/outside when taking off, putting on.

  • Do no use materials that can easily melt or fray

  • We are not recommending that you try and source N95-grade material


Some notes: ​

  • There is currently insufficient research on the efficacy of various fabrics for filtration in cloth masks. These recommendations are the best we have given limited information, but we will update this if/when more information arises. (We do have a sewist whose public health buds are doing a systematic review of all the research… so that’s something!)

  • Cloth masks are never meant to be used as substitutes for medical-grade PPE. These masks will be going to facilities that have need for a stop-gap during this extreme mask shortage: either to be used alongside N95s or for vulnerable populations who are not at the front lines.

A note about Oly-Fun Non-woven Fabric

  • In the past few days, a blog post went viral touting the (potential) efficacy of Oly-Fun non-woven fabric for use in DIY masks. We've done some research and have concluded that Oly-Fun is not suitable as a permanent construction element in DIY masks and can be used as a disposable filter only.

    • Oly-Fun is made of polyethylene fibers and is very moisture-resistant, and is likely to create moisture buildup inside the mask​

    • Oly-fun has a very low melting point and by the manufacturers instructions must be washed, dried, and ironed on cold/low temps, meaning it can not be sterilized in an autoclave

    • Manufacturer has also advised against machine washing entirely

    • Since this fabric has a low melting point, we have no recommendations at this time for how to sterilize it when sending it to hospitals, nor do we have any evidence that hospitals have approved protocols on how to sterilize the material upon receipt.




Tried and tested notions for attachments:

  • 1/4" or 1/8" soft elastic

  • Elastic hair ties

  • Bias tape: 1/2" pre-packaged or made by hand

  • Cotton twill tape (may need pre-shrinking)

  • Shoelace or athletic lacing

  • Strips of cotton jersey/t-shirt fabric (no hemming required)


  • We have received feedback from facilities that elastic, while more convenient than ties, can injure the skin on the back of the ears when worn for long nursing shifts.


Filters are designated as removable and can be either single-use or reusable depending on what they're made of. If your mask includes a filter pocket you are not obligated or expected to include filters in your shipping. If you do include filters, package them separately from the masks so they do not accidentally get ruined during sterilization at the facility.

Recommended filters:

  • USALab Qualitative Filter Paper

  • HEPA-rated vacuum cleaner bags, furnace filters, and tea towels are good alternatives

  • PM2.5 filters were recommended by one of our community members


  • Avoid synthetic woven materials not rated for filtration purposes