Three years ago, I posted the message below. At that time, I had tried full-strength Simple Green with no luck. Forgetting what I had tried back then, I again applied full-strength Simple Green, on a paper towel, to a test area. For whatever reason, all the gray streaks disappeared immediately this time.
So I filled a spray bottle with SG, squirted it as a stream, not spray, onto the gutters, waited about 10 seconds, then used a dustpan brush to swipe the sprayed area a couple of times. Clean like magic. Follow up with a generous hose spray of water.
Also removes stubborn gray stains from fascia boards. (They looked like mildew, but even full-strength bleach or Fantastic didn't remove them.)
Just remember to wear eye protection.
R1
*********************************************************** November 16, 2009They are discolored with vertical gray streaks on the sides, and gray spots on the bottom where water flowing down the sides accumulate in "puddles" along the bottom outside corner.
I've tried the following, applied with a saturated paper towel to small test areas:
-- full-strength bleach
-- full-strength Simple Green
-- full-strength white vinegar
-- full-strength TSP substitute
-- 91% rubbing alcohol. Some improvement, but labor intensive to do all
158 feet.-- paint thinner
I've also tried the following:
-- spray gas log cleaner
-- spray Fantastic
-- a mix of bleach with Oxydol laundry detergent, applied with brush. Makes some improvement.
-- a mix of 1 part Simple Green, 1 part bleach, 2 parts water, applied with a sponge. Makes some improvement.
I haven't tried ammonia, since I don't have any in the house.
I admit that I haven't had the patience to wait 5 to 10 minutes for any of the above to work. I was hoping to find something that I could apply with a dust-pan brush and have the streaks magically disappear immediately. Any suggestions?