Selecting Filtration Materials
Some very preliminary studies have shown cotton fabric along with two sheets of shop towels provides filtration efficacy significantly improved over that of cotton by itself as well as many other materials which are currently being used for homemade face masks, even approaching that of an N95-rated face mask. These tests are very preliminary and you should select filtration materials at your own discretion.
It is up to each user to select and prepare their own filtration materials.
MetaMotive takes no responsibility or liability for what any user may choose to use for their own filtration material.
Based upon some very preliminary but positive testing, the P-FAB-4 mask has been designed around the use of one piece of cotton fabric lined with two sheets of additional filtration material, though this mask may be used with cut-up pieces of t-shirt by themselves… which is good for those of us with no mask sewing skills.
You may wish to experiment with multiple fabric sizes to get the one that works best for you.
MetaMotive has been experimenting with ZEP shop towels for the additional filtration material, which are currently still available in auto parts stores and home improvement stores (as these are considered “essential services” in many states). Each shop towel is approximately 9”x 12”. The cotton fabric may be cut to a similar size if being inserted in between the layers of shop towels, or may be cut larger if the cotton fabric is intended to be used by itself or as the outside layer of other filtration materials (such as 10” x 12”).
Legal disclaimer again? Yup.