Best Homemade Face Masks to Protect From COVID-19 Combine Cotton and Silk, Study Finds

Members of the public looking to make a facemask at home to prevent the spread of COVID-19 should use a combination of cotton and natural silk or chiffon, according to scientists writing in ACS Nano.

The scientists tested a number of different materials and combinations to determine the most effective way of limiting the spread of the virus that causes COVID-19. According to their results, cotton and silk (combined) make the best masks. They also stressed the importance of making the mask fit properly. Even a small gap can drastically reduce effectiveness, regardless of the material it is made from.

From Texas to California, Americans are being asked to don masks when out in public to reduce infection rates.

The Centers for Disease Control and Prevention (CDC) has also recommended wearing a mask, but says members of the public should avoid surgical masks or N-95 respirators, which are in high demand and should be saved for healthcare workers and first responders. Instead, the CDC recommends cloth masks and offers a guide on how to make your own at home.

Masks provide a barrier, effectively blocking the respiratory droplets released when we sneeze, cough and breathe from reaching a new host.

A face mask might not prevent the wearer from contracting the virus that causes COVID-19. However, it should protect others from infection if the wearer is carrying the disease, even if they are not showing symptoms.

Many materials can block larger droplets, but smaller droplets (called aerosols) can easily slip through the cracks, getting out through the openings between cloth fibers. To find out if certain materials were better at catching aerosols than others, scientists at the University of Chicago tested different fabrics from flannel to Spandex.

Using a fan, the team blew different sized particles, ranging from 10 nanometers to 6 micrometers in diameter, towards a sample of fabric. The rate of airflow was tweaked to match the speed of a person's breathing at rest.

Pedestrians wear face masks
Women wearing protective masks are seen as major cities in the U.S. adjust to restrictive measures during the coronavirus pandemic on April 22, 2020 in New York City. A new study suggests cotton and silk make the most effective face masks. Mike Lawrie/Getty

According to the study, a layer of tightly woven cotton combined with two layers of polyester-spandex chiffon was the most effective at blocking aerosols, filtering 80 to 99 percent of particles depending on the size. However, the authors say the chiffon could be swapped out for natural silk or flannel for similar results.

The scientists explain the reason for its effectiveness lies in the fact that the high thread count cotton provided a physical barrier to the particles, while the chiffon or silk provided a static charge that offered an electrostatic barrier.

However, they warn the benefits of a cotton-silk mask could be undone if the mask isn't sitting tight. The researchers found even a one percent gap could reduce their effectiveness of filtering particles by half.

The below infographic from Statista shows the number of confirmed COVID-19 cases in the U.S. as of April 24, 2020.

Coronavirus U.S. Statista
Number of coronavirus cases in the U.S. as of April 24. Statista

Centers for Disease Control and Prevention Advice on Using Face Coverings to Slow Spread of COVID-19

  • CDC recommends wearing a cloth face covering in public where social distancing measures are difficult to maintain.
  • A simple cloth face covering can help slow the spread of the virus by those infected and by those who do not exhibit symptoms.
  • Cloth face coverings can be fashioned from household items. Guides are offered by the CDC. (https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/diy-cloth-face-coverings.html)
  • Cloth face coverings should be washed regularly. A washing machine will suffice.
  • Practice safe removal of face coverings by not touching eyes, nose, and mouth, and wash hands immediately after removing the covering.

World Health Organization advice for avoiding spread of coronavirus disease (COVID-19)

Hygiene advice

  • Clean hands frequently with soap and water, or alcohol-based hand rub.
  • Wash hands after coughing or sneezing; when caring for the sick; before, during and after food preparation; before eating; after using the toilet; when hands are visibly dirty; and after handling animals or waste.
  • Maintain at least 1 meter (3 feet) distance from anyone who is coughing or sneezing.
  • Avoid touching your hands, nose and mouth. Do not spit in public.
  • Cover your mouth and nose with a tissue or bent elbow when coughing or sneezing. Discard the tissue immediately and clean your hands.

Medical advice

  • Avoid close contact with others if you have any symptoms.
  • Stay at home if you feel unwell, even with mild symptoms such as headache and runny nose, to avoid potential spread of the disease to medical facilities and other people.
  • If you develop serious symptoms (fever, cough, difficulty breathing) seek medical care early and contact local health authorities in advance.
  • Note any recent contact with others and travel details to provide to authorities who can trace and prevent spread of the disease.
  • Stay up to date on COVID-19 developments issued by health authorities and follow their guidance.

Mask and glove usage

  • Healthy individuals only need to wear a mask if taking care of a sick person.
  • Wear a mask if you are coughing or sneezing.
  • Masks are effective when used in combination with frequent hand cleaning.
  • Do not touch the mask while wearing it. Clean hands if you touch the mask.
  • Learn how to properly put on, remove and dispose of masks. Clean hands after disposing of the mask.
  • Do not reuse single-use masks.
  • Regularly washing bare hands is more effective against catching COVID-19 than wearing rubber gloves.
  • The COVID-19 virus can still be picked up on rubber gloves and transmitted by touching your face.
Best Homemade Face Masks to Protect From COVID-19 Combine Cotton and Silk, Study Finds | Health