Cloth Masks through SEM imaging

Last updated: 18 Nov 2021 | 3654 Views |

With the current COVID-19 pandemic, face masks have become a part of everyone's daily life to help slow the spread of the virus. The US Centers for Disease Control and Prevention released findings that double-masking can be an effective way to reduce the transmission of the coronavirus that causes Covid-19. The method of double masking recommended by CDC is to wear a cloth mask on top with a disposable medical mask underneath. The cloth mask will add up layers and pin down the side gaps of the medical mask improving performance and reducing SARS-CoV-2 transmission and exposure.

Cloth Masks

Cloth Masks can be made from a variety of fabrics and many types of cloth masks are available. Nowadays, Cloth masks are not just a product or a protective equipment, they are also a tool to showcase innovation potential of the life wear. Some of the products prioritize high-quality fabrics, adequate ventilation, and a delicate texture. Some claim to feature a coating (Nano Hydrophobic Filament) that prevent water droplets from penetrating which is helpful for reducing the spread of germs from coughing or sneezing.

SEM imaging

In this Cloth Mask through SEM imaging experiment. We selected cloth masks that is on the Thai market by popular brands with claims that the cloth masks can be use through 30 wash cycles to see close images and changes through washings.

Our Hitachi Scanning Electron Microscope Model SU3900 captured these pictures at 1000x magnification to see the physical properties of new mask and observe how the fibers of the masks change after washing (Wash 30 times by hand with detergent).

Brand	Condition	Thread shape	Thread size	Woven density	Coating
Brand A	before wash	round	thin with moderate size consistency	High density	high density and spread thoroughly
Brand A	after 30 washes	some were damaged	expanded	moderate loss of density	some washed away
Brand B	before wash	round	thick with high size consistency	high density	moderate density and spread thoroughly
Brand B	after 30 washes	maintained shape	maintained size	maintained high density	mostly washed away
Brand C	before wash	uniquely flattened	thick with high size consistency	high density	high density and spread thoroughly
Brand C	after 30 washes	mostly maintained	expanded	moderate loss of density	mostly washed away

Brand	Condition	Thread shape	Thread size	Woven density	Coating
Brand D	before wash	round	thin with hign size consistency	high density	moderate density and spread thoroughly
Brand D	after 30 washes	maintained shape	maintained size	maintained high density	mostly washed away
Brand E	before wash	round (distort and split)	uneven size	low density	low density and not spread thoroughly
Brand E	after 30 washes	some were damaged	expanded	moderate loss of density	mostly washed away

SEM photos show the characteristics of fibers and coatings, and 4 out of 5 brands have decentmask quality. The quality of the fibers in the mask is reduced after washing, and the coating material is noticeably lost. Washing causes varying degrees of deterioration and coating loss in each brand of mask.

Surfaces can be analyzed using Scanning Electron Microscopy at magnifications ranging from hundreds to millions of times. EDS Analysis also provides elemental and chemical analysis of a sample within the SEM.

Instrument | Hitachi Scanning Electron Microscope

Reference

Brooks JT, Beezhold DH, Noti JD, et al. Maximizing Fit for Cloth and Medical Procedure Masks to Improve Performance and Reduce SARS-CoV-2 Transmission and Exposure, 2021. MMWR Morb Mortal Wkly Rep 2021;70:254–257. DOI: http://dx.doi.org/10.15585/mmwr.mm7007e1

SEM Application Mask scanning electron microscope