Cleaning SBPP masks in a rice cooker?

Rice cookers and slow cookers and "Insta Pots" are all the same family of device.

We're looking for ways to clean SBPP masks. One reference guide that stands
out is Dry Heat as a Decontamination Method for N95 Respirator Reuse. 

Here's a video by University of Illinois, Urbana-Champaign:

And here's what happens to a SBPP I sewed:

The elastic is just fine, but the SBPP has melted then hardened again. 

N95 class respirators are a sandwich of polypropylene layers. 

There's SBPP as we have it here but far thinner, sandwiching 

melt-blown PP that holds the electrostatic charge. 

It could be that the method works for masks that feature the 

type of SBPP we're using, but that's probably so fiddly that it's be 

impossible to instruct world citizens on how to do it.

Why are we doing this - all cleaning methods will likely drop the 

filtration of SBPP - clumping of fibers. It is just a question as to how much. 

Indeed, is that less and less of a drop each time the mask is washed 

or does it keep going precipitously?  

Most likely this affects all spunbond materials in the same way, 

but on different curves.  More research needed.

Full disclosure: the mask I made was tested by friends elsewhere, 

who for now are not wanting to be named. For later they are:

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Repeating the tests myself

Insta Pot in garden (for safety). Electronic thermometer threaded 

in and as close to the center of the base as I could get. The trivet is at the 

bottom, then a couple of cotton face cloths, then the masks just below the lid:

This was hellishly hard to get to 100°C and keep it there. Slow cooker settings 

were too slow, and "Rice" and "manual" made it rocket to towards 140°C 

which is dangerous as PP melts at 160-170°C.

By turning it on and off, and even venting the lid I was able to keep the base temp 

between 95 and 115. Well mostly. Sometimes I'd cut the power at 115°C and it 

would still climb to over 140°C. Problematic, I'd say. I sampled the temp of the 

mask area a couple of times and it seemed to be 60-80°C which is what is wanted.

Masks after extraction

 

1: Air Queen KF94 (used a few times)

2: three layers of ILC 151 52-GSM spunbond polyester (SPPE) 

3: four layers of 38 GSM smart-fab  in RagMaskMax style   

4. some 68 GSM generic SBPP from an online store (in an elastic band - not a mask)

5: some 270-GSM spunbond polyester in an elastic band - not a mask)

6: Four layers of 80 GSM SBPP in a boat style mask.

All these were fine. They looked fine. Touch was 

identical as before they went into the pot. Not PFE tested though.

I suspect the tests my friends did were far hotter than the melting point of SBPP 160-170°C

Next test: put them all in again, but keep the electronic 

thermometer with the masks and not on he metal base of the pot.