What fabrics to choose to make your homemade mask?
If it is possible to make a cloth mask yourself, there are several questions to consider: should you choose cotton or polyester? Is the performance still there after several washes?
To answer this, UFC-Que Choisir from France tested several types of fabrics purchased, taking into account two evaluation criteria: filtration efficiency and breathability.
To limit the risks of a resumption of the coronavirus epidemic, the use of face masks for the general public has been made mandatory in all closed places, in addition to barrier gestures. Therefore, it has become essential on a daily basis. In addition to surgical masks and FFP2 masks, it is possible to manufacture cloth masks yourself, which have the advantage of being more durable and therefore cheaper in the long term. In fact, the latter are washable and can therefore be used multiple times, after machine washing at 60 ° C. However, on the condition that you find the right tissue because not all are the same, as several scientific studies on the subject have shown.
To help people, UFC-Que Choisir decided to conduct its own tests, which consisted of purchasing different fabrics and two-layer set laboratory tests to determine if homemade face masks made from these fabrics met the requirements. "For this, breathability (respiratory resistance according to ISO 9237) and its filtration efficiency (resistance to penetration of particles of more than 3 µm) were evaluated at nine and after ten washes." Three types of masks can be made: pleated (with horizontal folds), vertical seam ("ninja" masks) and duckbill.
Lycra, cotton. A dozen different fabrics tested and compared
As the organization explains, the equation is not simple because the fabric must not only stop the drops that can carry the virus. It must also guarantee good breathability: a very important criterion for the mask to be supported, for example, on public transport with little ventilation or in hot climates. The fabric should also be flexible enough to follow the contours of the face and soft enough not to irritate the skin. In order to make an informed decision, we are invited to trust the recommendations of Afnor (French Association for Standardization) that has issued a mask pattern and has specified the appropriate fabrics when evaluations are available.
"For those who do not know if the fabric at their disposal falls into these categories, Afnor recommended a reference set consisting of: a thick fabric, a technical polyester shirt layer and a piece of fine cotton," recalls the UFC- Than Choisir. But now that it's possible to shop for fabrics in the store and choose from a wide variety of products, its expert lab tested 14 textiles to find out. Among these: denim, thick or classic cotton jersey, fleece, lycra, sports or satin polyester or cretonne. Filtration and breathability measurements were carried out twice: after nine washes and after ten washes.
Combining efficiency and breathability is not easy
Therefore, 14 homemade cloth masks were designed (2 layers at a time, except denim). Then, their test results were compared to the performance of two barrier masks for non-sanitary use that meet AFNOR standards, one category 1 (filters more than 90% of particles larger than 3 microns) and the other of category 2 (more than 70%). But also two disposable homemade face masks made of cellulose (Kleenex tissue and paper towel), making 18 in total. It turns out that the results are not all conclusive because the filtration capacity of the particles at nine o'clock and after ten washes was weak for masks made of foil, lycra, cretonne or Burlington.
Regarding the conclusive analyzes for filtration, only two sets give results similar to those of a category 2 non-sanitary mask, even after ten washes: a polo-type pique mesh fabric and a polyester satin lining similar thick. Because if "thick or simple T-shirts filter very well, they prevent breathing too much (breathability after nine washes and after ten washes). Cotton poplin, Japanese fabric and denim have the same drawback", Specifies the UFC- Than Choisir. Clearly, if some fabrics offer more or less good filtration, this is not the case for breathability, and vice versa.
In the end, the organization recommends choosing a certified or surgical mask to ensure its performance. Unless you do a little trick: Add a deployed tissue to your homemade face mask, like a kind of filter (third layer). "Because the Kleenex that we included in the test is working with honors, in both evaluation criteria. If you have doubts about the tissue you are using for your masks, you only need to provide a space between the two layers to slide a handkerchief and get enough protection , readily available and inexpensive, "he concludes. However, it must be replaced regularly because cellulose is sensitive to moisture.