Safe coating to make a 3D printed respirator mask airtight What is a good example of something safe that could be applied as a coating layer to the walls of a 3D printed respirator mask to make them truly airtight (seal pores and fissures) while (ideally) satisfying the following criteria?:


Not air permeable at the pressures created when a person inhales
No (or low) VOC out-gassing from the coating
Does not impose health risks to the respirator wearer
Can be applied by dipping (or maybe spraying)
Forms a thin layer that is flexible enough not to crack during normal use of the mask


Here are some materials I have been considering for the job:


White glue (school PVA glue): Seems safe. Is is airtight?
Water based liquid rubber: some SDS suggest it's safe. It's marketed as watertight (but is it AIRtight?)
Some sort of common paint?


If someone here could suggest some potential coating materials or knowledge bases where I could check their non-permeability/safety, I would be really grateful.

As I'm not a native speaker, I apologize for any broken grammar.



The problem: It is well known that 3D printed objects are usually not exactly airtight, due to micro-fissures. To make things worse, I ordered a DIY 3D printed respirator mask (composed of ABS plastic) that is visibly permeable to air (one can literally see the tiny gaps all across it's walls' surfaces through which air and viruses could come in when the wearer inhales).

P.S.: Silicone caulk might not be an option, since it's too viscous and would be a mess to apply to the outside of the respirator, rendering an unprofessional finishing. I should note that I could possibly apply it only to the inside of the walls, but I intend to coat all surfaces, just to be extra safe.
You need something flexible and airtight. Could neoprene fabric, like it's used for diving suits do the trick, esp. for prototyping? Otherwise, I thought of injection moulded silicone, as it's used in diving goggles.