On average, the homemade masks captured 7% fewer virus particles than the larger bacteria particles. However, all of the homemade materials managed to capture 50% of virus particles or more (with the exception of the scarf at 49%).
Although the tea towel and the vacuum bag captured the most particles, they were also the hardest to breath through. With two layers, the tea towel was over twice as hard to breathe through as the surgical mask. In contrast, the pillow case, t-shirt, scarf, and linen were all easier to breathe through than the surgical mask.
Based on particle capture and breathability, the researchers concluded that cotton t-shirts and pillow cases are the best choices for DIY masks....
Bottom line: Test data shows that the best choices for DIY masks are cotton t-shirts, pillowcases, or other cotton materials. These materials filter out approximately 50% of 0.2 micron particles, similar in size to the coronavirus. They are also as easy to breathe through as surgical masks, which makes them more comfortable enough to wear for several hours.
Doubling the layers of material for your DIY mask gives a very small increase in filtration effectiveness, but makes the mask much more difficult to breathe through.