OK, I agree that Acetone is the better choice for soaking and cleaning your Vapman. I would still use caution on any finished surface when using both Acetone and Alcohol though.
OF's remarks on water content make sense. The 70% and 90% on the alcohol means alcohol to water content (90% alcohol to 10% water, so water could stay in the wood and cause some grief.
Now, that's a pretty beat up - I mean, we'll used Vapman, Steama!
Mine has been heavily used for at least a year now and still looks almost new. I've combusted a few times which left a few black dots in the Bowl.
This pic is a bit blurry, but you can see its still in great shape. I really like the charred Basic/Pure version because I feel I can clean it better than a Mica. I can sand the inside wood around the Bowl every few months.
Also, I always wipe the bowl with some tissue and wipe it with Alcohol every now and then - you can also use Acetone
I also sand the metal filter with 1000 grit wet sand paper and it ends up like new. I can't get the stains out any other way.
I can post more and better pics tonight.
I'd love to see more bowl pics.
Peace.