Yes, Revelle masks are made with 3 layers of high-thread cotton - each layer is sawn with a central seam.
The top two layers are connected with an overlock seam in between. The 3rd layer (which is made out of 100% organic cotton) isn't sewn to the top two and hence creates another layer of protection.
We spent a long time researching the best way to design a good mask, paying attention to 4 areas:
In the process, we have done multiple 'candle blowing' and 'match blowing' tests with various fabrics.
We chose fabrics that provide comfort, and at the same time pass the 'candle blowing' test.
The masks also have an inner pocket that allows inserting an additional layer for protection, if needed.