Test results in for the six layer satin mask

TL;DR: It wasn't anywhere near 93%, sadly. At least for particle sizes lower that 3.5 microns, which is an important group.

The lab of Volckens Group at Colorado State University tested the mask I mailed them. 

I had hoped that this would serve as a contingency mask for workers that needed high protection. Contingency for when boxes of N95 or FFP2 are empty, and the bosses are unwilling to compete on the global supply chain for the current bulk purchase prices. The fabric (six layers) would need to be closer to the red line to be useful that contingency guise.

If you changed to (say) 12 layers of satin which is only a little harder to make (an additional 60 seconds per mask) then you get better filtration perhaps, but still not at that 95% line. Though the graph above shows "N95 reference" at the 100% line for the whole range of particle sizes. And 12 layers of satin would increase the breathability issues to the level where a "mask bracket" (retainer, bonning) is required again. Previous masks with 750 thread count cotton required that.

Prior info for this mask/fabric

Mask construction, incl video. The video was of the actual mask Volckens Lab tested.

Aaron Collins' 65nm test of the mask

Aaron Collins tested an identical RagMask Max (6 layers of this satin) in December.  If particle is smaller than the viron. For N95 / FFP2 masks this is fine as the scores Aaron has for those are always good. For cloth, this should be the lowest performing datapoint on the graph. Here's Aaron's new datapoint overlaid on Zach's April 2020 Portacount Fit testing machine results (fabric in a clamp).  The blue dotted line is Zach and Aaron's data together. Of course the nature of the curve is a prediction. If true ths would have been fine for a high-spec contingency mask, but the ColoState tests pour cold water on that theory :(

When Aaron did a second test with the edges pressed onto his face, the filtration was the same. Meaning for him at least the mask as supplied was a good fit. With Aaron's test he has a really really good way of gauging "fit" for a mask, even if the mask is a cloth variant versus his usual (far superior) N95, KN95, FFP2, KF94 core test group.

Aaron also washed the mask, dried it and tested again, and the filtration went up to 65%. 

Wire Cutter (New York Times) article

This batch of masks was done before mine. My test was not quite as depicted in the article - my six layers of satin was cut out from the mask and tested in custom equipment.  Here's my result superimposed on their results:

I'm confused in the wire cutter article about why all the masks on the chart reach (say) 95% only and don't climb to 100% protection as mine does. Also why the control N95 mask is at 100%. I've emailed them to suggest that.

Regardless, My six of satin layers wasn't high on the leaderboard :(

Note: this is Polyester satin from inexpensive sheets from Amazon, not sateen (cotton) or any silk product with similar weave.

TODO: further analysis of numbers, including a graph that overlays the results from other (amateur) tests - when I get the raw numbers to put into my own plots. 

Next experiment in #maskTech

Back to the high thread count cotton I think.- I have 750 count sheets left from premium UK store "Marks and Spencer" purchase


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