Expert: James Yee - 10/22/2010

Question
My last humidification device developed a mass of white mold on the front of the unit, I have since removed it and ordered a similar device to replace it. My question is, is there a way to prevent the mold from re occurring? Boling my "cigar juice" or microwaving the oasis foam , maybe? Any help would be well received- Evan

Answer
Hi Evan,

Mold can appear due to one or more reasons.  First, mold can appear when your humidor has high humidity for a prolonged amount of time.  Mold usually appears when the humidity is greater than 75% so it's always best to keep the humidity lower than this mark.  The humidity safe range for cigars is between 67-73% humidity and 70% is considered ideal.  If you're having trouble maintaining an ideal humidity level, a 50/50 mixture of propylene glycol (PG) and distilled water should balance the humidity out at exactly 70%.  (If the humidity is still high after adding the mixture, fine-tune the mixture with a few more small drops of PG.)  NOTE: After adding it, PG may need a week to stabilize the humidity so wait a week before you fine-tune the mixture.  PG can also last a long time in your humidor (on average, 2 years) so you only need to add it just once.  Once you've acheived the ideal humidity level with PG, all you need to do is add distilled water to the Oasis when needed.  If you're using a pre-mixed humidor solution and the humidity is still too high, you can still buy a small bottle of PG and fine-tune the mixture with a few small drops.

Another cause for mold growth is water.  Be sure that you only use 100% distilled water or "bidest" water (double-distilled water).  Any other types of water (ie: boiled tap, bottled drinking water, filtered water, etc.) will contain mineral particulates that can buildup in your humidor over time.  This creates a chalky, powdery substance that is similar to mold in appearance.

Aeration is also important.  To reduce the chance of mold forming in your humidor, it's important that your humidifier is not obstructed by anything such as the humidor trays, shelves, dividers and/or the cigars themselves.  Obstructing the humidifier will prevent proper humidity flow and this can cause a moisture buildup on the humidifier.  This moisture buildup will lead to mold growth.  (You mentioned the mold forming on the front of the unit and this sounds like there is an obstruction that's creating moisture buildup.)

Mold can also form from bacteria transfer so it's always best to thoroughly wash your hands before you handle your cigars/humidor.  A slightly dirty or sweaty fingerprint and exposure to humidity is more than enough to cause mold to form.

It's not recommended that you microwave the oasis foam or boil the water/humidor solution.  If your oasis foam has come in contact with mold, you can soak the foam in some Isopropyl alcohol to kill the mold and then THOROUGHLY flush the foam clean with distilled water.  The plastic humidifier housing can easily be soaked in alcohol and then thoroughly rinsed and wiped dried.  This will remove all traces of mold clinging to the housing.

I hope this helps.  If you have any more questions, please feel free to just ask and I will be happy to help.

Regards,
James