Credit: NIST
The researchers looked at the yarn count, weave and mass of fabric samples such as this 100% cotton flannel (magnified about 220x times) — which was among the highest performers in their testing — in an attempt to determine how those characteristics affect the fabric’s ability to filter particles. The main image above, created by light shined through the fabric from below, reveals web-like structures that are common features in medical-grade masks. The smaller image made from reflected (direct) light reveals how the fabric would look to the naked eye under normal conditions.
Researchers have completed a new study of how well a variety of natural and synthetic fabrics filter particles of a similar size to the virus that causes COVID-19. Of the 32 cloth materials tested, three of the five most effective at blocking particles were 100% cotton and had a visible raised fiber or nap, such as found on flannels. Four of the five lowest performers were synthetic materials. The testing also showed that multiple fabric layers could improve cotton’s effectiveness even further. None of the materials came close to the efficiency of N95 masks.
Although the sample size was relatively small, the researchers noticed that tighter woven fabrics generally filtered better than knits and loosely woven fabrics. The 100% cotton fabrics with many raised fibers also appeared to filter better than cotton fabrics that lacked this feature. The raised fibers often form web-like structures similar to those in medical grade masks.
Three researchers from the National Institute of Standards and Technology (NIST) — Christopher Zangmeister, James Radney and Jamie Weaver — teamed up with Edward Vicenzi of the Smithsonian Institution’s Museum Conservation Institute to evaluate materials and determine both their ability to filter particles and their breathability. Their results appear in the journal
Support the originator by clicking the read the rest link below.
