JC Newman posted this on Facebook.   This is the method I have used to season my humidors.

After you purchase a beautiful new humidor, there is one more step before you can start storing your favorite cigars, the seasoning process. The seasoning process is crucial to preserving cigars and if skipped, the humidor’s cedar interior will actually rob the moisture from your cigars and ruin them. To ensure your cigars stay fresh just follow these five easy steps.

Note: JC Newman recommends the Craftsmen’s Bench humidor – which is a great one.  But I apply these principles to any humidor.  They also recommend JC Newman Cigars to fill in it – great cigars, but these apply to any cigars.

1. Wipe the inside of the humidor  – With a new sponge or cloth, wipe the entire interior of your humidor. Do not lay the sponge down directly on the wood and make sure it is not over saturated with water.
2. Fill your humidifier – Fill your humidifier with distilled water and place inside the humidor.
3. Close the lid and wait – Close the lid to your humidor (with sponge and humidifier inside…Cigar Coop note: I put the sponge on a piece of plastic wrap so it doesn’t touch the wood) and wait 24 hours.
4. Repeat – Remove the sponge and repeat the wipe down procedure in step 1. Close the lid and wait another 24 hours. Do not leave sponge inside this time.
5. Start using your humidor – Your new humidor should be ready for use now. Feel free to load it up with your favorite Cigars and enjoy a smoke for all your hard work. (If the cedar inside feels damp, wait one more day before storing.

Cigar Coop also recommends a digital hygrometer to monitor things the first few days.  It will probably be higher for the first few days than the recommended 70% humidity which is idea, but it should stabilize nicely within days.

I’ve also used this technique for a well sealed cigar box that can be used as a humidor.  The key thing is – the cigar box must seal properly to maintain the humidity, so check the edges very carefully when you close it.