What material is best to use for face masks?

Health agencies believe the Coronavirus transmits via respiratory droplets and the Centers for Disease Control and Prevention suggests homemade cloth face masks for use outdoors. However, the previous variability concerning the masks' success in limiting released droplets made some individuals hesitant or doubtful of their practicality during the recent Coronavirus pandemic.  Taher Saif, a Mechanical science and engineering professor reported about research he carried out along with his graduate students, Bashar Emon and Onur Aydin, on the success of general household materials for use in homespun facemasks.

The droplets launched during coughing and sneezing are larger than those launched while breathing and speaking and any of these droplets may hold numerous viral specks. The larger droplets do not travel far due to weight, but the smaller ones can travel farther, with the more of them staying within six feet of the contaminated person. Regrettably, because pre-symptomatic, asymptomatic, and symptomatic, carriers can disperse the coronavirus, it is only through testing that a conclusion can be arrived at about individuals that are the sources of infection. Therefore, a physical blockade, such as a facemask, can avert the transmission.

The droplets launched during sneezing and coughing are in numerous proportions and momentum. The material for any mask should be water-repellent and breathable to fast- and slow-speed droplets. It is crucial to understand that an extremely water repellent material will probably be less breathable. Low breathability will push air current through the sides and will conquer the function of the facemask; which means the facemask gives a flawed feeling of security. The option of material and the amount of layers has to be balanced between the degree of droplet repellence and the breathability. Both conditions should be maximal. The breathability and droplet resisting capability of general materials were tested. To gauge breathability, the airflow momentum is measured through the material. Measuring droplet blocking is a more complex procedure that involves the use of an inhaler to produce high-momentum droplets.

The nose of an inhaler is filled with distilled water blended with 100-nanometer fluorescent specks, which simulates the size of the coronavirus. When blown, the inhaler pushes the water through the nose and produces high-speed droplets that are gathered in a plastic dish positioned erect directly opposite the inhaler. The procedure is repeated with the material being tested over the dish gathering the specks. The quantity of water that gets to the dish is measured at both times by using a microscope to count the nanoparticles. The ratio of volume gathered with and without the material is calculated to arrive at the rate of the droplet repelling efficiency of the material.

A set of ten ordinary household materials were taken and their qualities were compared with some that had a dental/medical quality mask as a standard. The materials had a varied mixture of silk, cotton, and polyester. The breathability and repellent capability for two and three-layered t-shirt materials were also estimated. Two crucial discoveries were made.  Firstly, most ordinary materials, like T-shirt material, have 40% or higher droplet repelling capability when used as a single layer. However, in two layers, the T-shirt material had a 98% droplet repellent efficiency surpassed the efficiency of the medical mask, and also with superior breathability.

Secondly, most ordinary materials get saturated with water meaning that they are hydrophilic, but medical masks repel water which means they are hydrophobic. What this tells us is that ordinary materials make use of a proxy system to retain the droplets.

Suggested Material for Facemasks

It was discovered that very breathable materials are a fantastic choice, like general T-shirt materials; the reason being that they are inclined to have low droplet repellence, and their functionality escalates when used in two layers for a facemask. The overall breathability of the two layers of the T-shirt material is much better than that of the medical masks. More so, even with three layers of the cotton T-shirt material, the breathability is still better than that of a medical mask. What this means is that homemade masks can be a very functional apparatus for the outdoors, along with screening, social distancing, contact tracing, and other medications to alleviate the transmission of diseases.

Another school of thought also concluded that the pillowcase and the 100% cotton t-shirt are the best materials for homemade face masks. For them, the response is in the breathability of the material used.  That is the ease of breathing through your face mask is an important element that will determine how convenient it is; and convenience is not just for grandeur. Convenience will determine how long you can have your mask on.

Along with speck efficiency, the researchers tried the drop of pressure on each type of material. This is a positive pointer on the breathability of each material.  As a criterion, they also compared the breathability of each home-made mask material to the surgical mask; though the vacuum bag and dish towel caught the most specks, their breathability was very low. With two layers of the dish towel made it tougher to breathe through as the surgical mask. On the other hand, linen, t-shirt, pillowcase, and scarf's breathability were top-notch than that of the surgical mask.

So, based on speck collection and breathability, the researchers deduced that pillowcases and cotton T-shirts materials are the best options for home-made face masks. Invariably, the best options for home-made face masks are pillowcases, cotton t-shirts, or other cotton materials.

These materials strain out an estimated fifty percent of 0.2-micron speck, close the Coronavirus in size. All these materials' breathability degree is high. Making the layers of the materials double for home-made face masks just increases the filtration capability by a small difference but it affects the degree of breathability; making it more difficult to breathe through; however, the finest material for homemade face masks is most likely a mixture of two materials.