Expert: James Yee - 4/26/2008

Question
I have read much about using a 50/50 mix of PG and distilled water, but I am unsure about how to maintain the optimal mix over time.  It seems that the PG lasts "forever" and the water evaporates, so it makes sense to add water on a continuing basis.  What criteria do you use to determine whether/when more PG is needed (e.g. if the RH rises, does that mean PG is needed to moderate it?) ?

Answer
Hi Charles,

Yes, as Propylene Glycol loses its "potency" over time, the humidity will noticeably increase.  When this happens, you can either thoroughly flush the humidification element clean and start over with a new 50/50 mixture or revitalize the existing 50/50 dosage by slowly adding small drops of PG and fine-tuning the mixture again until is reaches 70% (or a humidity level that you desire.)

Though it's recommended that you flush the 50/50 mixture clean and start over, many people have found that adding a few more PG droplets is just as effective.  (I would recommend that the humidification element is flushed clean and a new 50/50 dosage is added.  Constantly adding to an old, existing mixture can clog your humidification element and impair its performance over time.)

A 50/50 dosage should be enough to balance the humidity out at 70% (the ideal humidor humidity level) but sometimes the humidity may be slightly off so after you've added your initial 50/50 mixture, monitor the humidity level closely.  If the humidity is still too high, there is more water than PG so fine tune the mixture by adding a 2-3 tiny drops of PG.  If the humidity is too low, there is more PG than water so dilute the mixture by adding 2-3 tiny drops of water at a time.  Be sure to allow the humidor to sit for a few hours between each additional dosage.  This way, the humidity will have time to fully stabilize.

It should also be noted that after your initial 50/50 dosage, your humidor will need at least 1 week for the humidity to stabilize.  During this time, the humidity may dip and peak wildly but don't worry, this is natural and temporary.

Hope this answers your question. If you have any more questions, please feel free to just ask and I will be happy to help.

Regards,
James