A co-worker of mine asked me today how to get tanning accelerator out of his deck. Apparently his 5 year old son got a large bottle of it while unobserved for a few minutes and sprayed it all over the deck & railings (8x32 feet). He is despondent at the dramatic color change. I promised I would consult the teemings on his behalf; any suggestions?
Powerwashing with a water+ detergent mix is the only thing that comes to mind. I have done this to outdoor wooden furniture, and it essentially blasts away the top weathered wood layer. Of course this will change the look of the wood in the powerwashed section so the entire deck will have to be powerwashed for color uniformity.
Worth a try… I think the best he can do, actually. From what he said, the whole deck looks like it was soaked in used motor oil.
If that doesn’t work then about the only thing you can do is take a large power sander (the kind you use for wood floors) and hope it didn’t go too deep.
It’s a bit extreme but I’ve used oven cleaner to get old, soaked in, dried oil out of rifle stocks. Use with caution and test carefully on a hidden area first.
I do not want to sound negative, because I’d really like to see this guy get the stuff our of his porch…But water and detergent are not going to get oil out of the grain of his wood. Oil soaks in, and quick. I had a similar problem with a large oak table I was referbishing. The top of the table (after I sanded all the old varnish off - so it has no protectant) there spilled a large amount of linseed oil. Mildly freaking how the heck was I going to get it off… I cleaned it up quickly, and started thinking. In the end I brought it to a mill where they had a 36" plane. And they planed it an 8th of an inch and that did it. Took the oil right out.
So unless he can power sand it, or somehow unattach it and plane it, He may have to replace the boards…how vast is the damage?
The kid apparently sprayed the stuff (a whole quart spray bottle) on the whole deck. As in flooring, rails, posts… everything. Several kilobucks to replace.
Of course, by now he knows kids do this kind of stuff.
Thanks to all for the replies!
Let me guess? Natural Treated wood? So painting over it after a power sanding or whatever is out of the question? Just a suggestion.
I don’t think that’s coming out. Oil is good for wood though; I’d get some tung oil and use it on the parts he missed. That way it’ll all match while it wears off anyways. (Tung oil has a vaguely orangey tint to it, which I assume the tanning solution would as well.)
Things I use to cut grease/oil around the house are ammonia and/or rubbing alcohol. I wouldn’t use EITHER on wood though.
The stain is BLACK. Ugh.
Well, your friend may have lost a deck, but he’s gained an embarassing story about his son that he can tell after he’s grown up. 
(Seriously, that really does suck. I’d be pretty distressed if my nice deck got trashed.)