whats the difference between mold and mildew?
There isn’t any sharp distinction between “mold” and “mildew”. Both are microscopic species of fungi that grow as long filaments. There are many species of mold, and those molds that grow on stuff around our houses, especially in wet places like shower curtains or behind walls, we call “mildew”. Other molds (like the ones that grow on food) we just call “mold”. “Mildew” also refers to several particular species of molds that grown on particular plants. There, “mildew” is just part of the name of the species (e.g. powdery mildew) but is really yet another species of mold. Sources: http://www.housekeepingchannel.
A mycologist or a good text will tell you what substrates a particular mold has been known to grow on and which types of material it prefers. For example, mildew is unlikely to be found ever growing on an indoor surface (except for a house plant), since mildew is a pair of sub-group of molds (powdery mildew and downy mildew) which grow only on living plants. You won’t find mildew inside, current indoor mildewcide and mildew-resistant products notwithstanding. We think it’s just a less scary name that some folks like to use. Indoor samples that contain molds that are not believed to not grow on building materials are thus unlikely to point to a problem. Other indoor molds, including some of the Basidiomycetes, are water and rot indicators. See Mildew Photographs for details.
