Assistant Professor of Northeastern University states that the protection from cloth masks would improve by the addition of a nylon stocking layer.
NPR published an article on the research of Northeastern University. It added that according to the researcher, the nylon layer would create a tight covering around the face, which would reduce the airflow. They mentioned that the nylon layer would work similarly to a seal of an N95 respirator.
The COVID-19 pandemic has given rise to a lot of potentially dangerous misinformation. For reliable advice on COVID-19 including symptoms, prevention and available treatment, please refer to the World Health Organisation or your national healthcare authority.