I purchased it this morning and just tried it, and while it certainly did much better than anything else I've tried it didn't get it all. I suppose I could keep adding more TSP to the water to strengthen it even more (I already doubled the stength), but I think it would probably wind up stripping the finish and need repainting anyway. And the work involved to remove every square inch of the soot just won't be worth it. It will take much less time to apply the Kilz and repaint. Of that I am now certain. Plus I just hate working with such strong stuff...constantly afraid some will flick into my eyes or get on my skin or some other unwanted surface. And now I'll need to educate myself about appropriate ways to get rid of half gallon or so mixture. I'm going to guess that tossing it down the sink may not be the best thing.
I did try it out on some stubborn grime areas around the house and it truly is effective. So perhaps I'll find some other use for the left over mixture short of tossing it out.
Oh well, a big lesson learned about candles in the bathroom...or ANYWHERE in the house. I've discovered there are different kinds of wax and should look for petroleum-free, nonparafin varieties for both health reasons (toxic carbons) and to avoid smoke staining/soot. Like these made from soy:
http://www.greenspacecandles.com/soy.htmI also learned that the wick must be kept short, about 1/4 inch, or it will make black smoke. So will remember to trim them before use. I wonder if this goes for tea candles as well?
For anyone else who might be interested, there's a pretty good discussion about this problem
here:
http://www.consumersrevenge.com/reports/candle5.htm