There is no such thing as "multiple coats" unless it is applied via dipping, which no one does for insect habitats. Some vendors who recommend multiple coats may be referring to the application of subsequent coats while the first layer is still wet, but this is not only wholly unnecessary, as long as the first coating is uniformly applied, but also likely to cause more harm than good, for the reason listed below:
Fluon is typically brushed onto a surface, after which the water evaporates, leaving behind a thin, dry film. The film is most fragile when freshly applied, so it's important not to smudge or scratch it. If brushed again after drying, the original film will either be rubbed off completely, or will leave behind many small clumps all over the application area.
Here are the instructions specific to the little Fluon applicators I sell on Amazon (currently sold out, as of this writing), which also contain some general information that may be helpful for anyone who uses Fluon.
Edited by drtrmiller, April 4 2018 - 1:58 PM.