Pearl Sutton wrote:
Judith Browning wrote:I wonder about using some of the non woven things used in clothing construction like pelon or some other interfacing fabric sold by the yard (or something similar to the vacuum cleaner bags mentioned in Anne's quote above) that might filter but not make such a humidity pocket behind the mask like a cotton fabric does?
If you make it so it doesn't sit right on the face it would help. Ever worn a proper gas mask with filters? The face part is a rubber thing that makes an airspace above the nose and mouth, the filters come in off the side. Some of them have a one way valve exhale ports. That might all be ideas to look at. I'm a recycle type, I'd probably use something like a margarine tub out of the trash that I heat shape, then add filters to the sides, and output with one way flaps and separate filters. hmm. Now you have me thinking...
Thinking on it more, if the input and output filters are separate items, you can change/wash/throw away only the ones you need to. If the mask is on a person with CV, change the output filter more, their inputs will last longer. The caregiver though would change their inputs more, their output will last longer.
This is a paint spray mask, visual of what I'm thinking of... Only homemade, and with the output filtered too...
The idea actually makes sense-you’re basically describing a separated inhalation/exhalation system with replaceable filters, similar to professional respirators.
But there’s one key issue: in real systems like that, everything depends on a proper seal and carefully engineered airflow resistance. In DIY versions, the common problems usually aren’t the concept itself, but things like:
the mask not sealing tightly enough to the face (even small leaks drastically reduce effectiveness),
one-way valves not functioning reliably or allowing backflow,
materials (like plastic containers) deforming and losing shape or airtightness with heat, moisture, and breathing pressure.
Your idea of separating intake and exhaust filters is actually used in professional-grade equipment, especially in medical and industrial respirators. However, those systems are tested and certified, because without proper validation the real-world protection level can drop significantly.
If you wanted to develop this further, the safer and more practical approach would be to start from a certified respirator facepiece and then explore modular or replaceable filter configurations around that, rather than building the entire structure from scratch.
Overall, it’s an interesting line of thinking but this is one of those areas where “almost works” can effectively mean “doesn’t protect.”