A couple of weeks ago, I cleaned down and re-stained the deck; I was happy with the job: it was a pretty even finish, using a brand of stain that I've used for a number of years.
Yesterday -- some 10 days after staining, and after intervening rains (which had pooled on top and then dried off with no adverse effects) --
- some light light splotches, of random pattern appeared. It was like somebody had splashed a fair amount of light bleach here and there, which had then dried off.
I'm going to have to refinish and stain the deck (again....), but I'd like to nail down where this splotchy-bleach effect might have come from so that I can avoid it next time.
The only thing out of the ordinary that's been going on when this happened is that my neighbour has a roofing company in, who are putting a flat roof (well, very shallow pitch) over his rear kitchen extension. They've boarded it out; put on the felt; and are out there this morning, presumably finishing it off. (I can hear blow-torches.)
Is there some chemical compound used when putting felt down on flat- roof boards that could find its way from one garden to another, and be caustic enough to created splotchy, lightly-bleach areas on stained wood?