One day I went to change my Filtrete air filter on my furnace, and it came out BLACK. I freaked out, went to the internet IMMEDIATELY to your site to find out what went wrong. Your website is SO UP TO DATE which lead me to the problem FAST. My granddaughter and I were making candles a few days earlier, which was one of the choices on your site! It could have a fan blower problem, which would have cost A LOT, but after following your directions I checked the filter again (no candles this time) and the filter was totally white. THAT WAS SUCH A RELIEF! The Filtrete Filter kept that black smoke from off of my walls! Thank you so much. I always have a stack of them next to my furnace so changing it is never forgotten.