Product review (1 stars): CONFIRMING: PRONE TO BLACK MOLD
I have to say that I had the same experience as everyone else reporting about the black mold problem that develops on the "new version" (or possibly fraudulent version) of these filters. They do not have the original blue outer layer, and are therefore prone to all kinds of mold and bacterial issues. I recently changed out two filters (I am running two different machines in a large room), both of which had turned black and slimy.

Since then, I have purchased and installed two filters from a new manufacturer that I am hoping will be better. So far, it seems they are working out fine and have multiple layers (the standard white paper layer, a blue plastic mesh, an aluminum ribbing for structural reenforcement, and an outer white fabric that seems to be similar to the blue fabric layer that existed on the original Honeywell brand filter. I am including a link to the new filters I bought, in case anyone else wants to give them a try. However, as of this writing, they seem to be backordered at the moment (I hope that's a good sign, that maybe it is a successful product).

<a data-hook="product-link-linked" class="a-link-normal" href="/BestAir-HW14-Honeywell-Duracraft-Replacement-Paper-Wick-Humidifier-Filter-7-9-34-x-3-1-34-x-14-34/dp/B004EZT38M/ref=cm_cr_arp_d_rvw_txt?ie=UTF8">BestAir HW14, Honeywell/ Duracraft Replacement, Paper Wick Humidifier Filter, 7.9" x 3.1" x 14"</a>