Red dust on mass air-flow sensor?

Topeka, Kansas, USA
1998 Chevy Tahoe
A month or three ago I replaced the mass air-flow sensor on my '98 Tahoe. Improvement was clear. What shocked me, was the thin layer of red dust on one side of the mesh and on the fine wires in the middle. My air filter to that moment, was a certain common brand known for red color and washability. I replaced it with quality OEM-style. I'm interested in better-than-OEM air filtration, especially cotton washables, but am a bit spooked. Recommends, anyone?
Cotton gauze filters worked better than all the other mesh/wire and sponge aftermarket filters, but still not as good as the OEM paper filters.

You can either have great flow or great filtration, not both. Going to a larger airbox and filter is a possible exception in some circumstances though.

Was the filter you use impregnated with oil? That usually minimizes the tiny particles getting through, but this does need a recharge every few months IMO.
I was indeed using an oil-impregnated filter, red-colored oil, and I kept up the recharging. I have to wonder if the powder was actually dried oil.

When using cotton mesh or foam type filters that need to be cleaned and oiled to increase their dust retention one has to be careful that they are not heavily saturated as that will over time cause oil build up on the AFM and it will need cleaning.
Well well. Got it! A while ago I was googling and saw some blue washable filters which explicitly did not use oil; anyone know if this is a direction worth going or avoiding?
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