Yes, that works. The water-based inks in our e-4500 / e-4600 textile markers have a neutral smell. After fixing the inks by ironing the fabric (without steam) the textiles should be washed at up to 60 °C. After that process, there is no risk from the substances used in the inks when breathing through masks decorated with the e-4500 / e-4600 textile markers.
For protective masks used as personal protective equipment or as medical devices for professional users, the manufacturer's instructions must be followed.