What is the white powdery substance that I’ve seen on some cigars?
This is called bloom and results when the wrapper’s oil matures. It is simply the residue of the wrapper’s oils fermenting. Just wipe it off with your fingers, it’s harmless and a good indicator that the leaf is of good quality. It is also a sign that you are storing the cigars in the proper temperature and humidity. You can prevent it by keeping the temperature and humidity down where you store the cigars.
