I have recently had the same problems as you. After long debate I have realized that I need some sort of a cover on my tortoise table. I have mine in my basement with an average temp of 72 degrees. Whatever misting, spraying, soaking I do the dry air of the house eats it up right away. Fighting a losing battle here in Illinois during the winter.

I recently sized up some plexiglass and placed it over my enclosure. The only part open air...is for my heat emitter and my hide...which is covered. I then put a large cup full of water and newspaper in the tank which assists me after I mist daily. The humidity has stayed over 75% with this set-up for a while. (only a two day experiment so far...so this is not a guaranteed solution, but an on-going test with good results.) I still have been misting, but I feel like I can leave my house now for an evening without worry

I hope this helps some.