Basement Air Filter Box: Ewww!

Late last year I assembled four air filters and a fan quintet into a box filter:

Running continuously for three months made the air filters look like this (with an unused filter on top for comparison):

I have not stretched the image contrast, so the new filter isn’t the pure white in the top picture, but it’s still about the same white as the cardboard frame. The floor is, indeed, painted gray.

Looking at the pleats in the other direction to show I’m not making it up:

The inside surface of the filters has the same gray appearance. The fans are, unsurprisingly, immaculate.

Totally did not expect that!

The filters sport a MERV 13 rating and snag “most smoke” from the passing air, so they’ve been collecting any fumes not sucked out of the laser cutter, along with whatever arises from other Basement Shop™ activities.

So I’ll buy another set of filters, build another box, and see what accumulates during the next three months.