Pressure washing left discolored areas on roof


I have read that an asphalt shingle roof should not be pressure washed, but I have also read that it is ok at low pressure.
Using low pressure, a guy pressure washed my asphalt shingle roof. Now there are some irregular areas that are lighter than the rest. The chairman of the board (my wife) does not like this. I think the guy said the lighter areas are the color the shingles are supposed to be (the color they originally were) and the darker areas still have stuff on them that the light pressure washing did not remove.
Is there a coat that can be sprayed on to get my roof to be a uniform color? Thanks. Ed
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I have to satisfy myself that the idiot never removed any of the "grit" causing the shingles to be lighter than the others.
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In article

I guess that is possible. I have climbed my last roof so I will get somebody to go up and look. I would still like to know if something cosmetic can be done to get a uniform look. Thanks. Ed
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Ed Wicks wrote:

    I know of nothing to do what you want, but the reality is that soon the dark area will probably return and it will be a moot point. I did pretty much what you describe to my light green colored roof to remove the fungus from the shingles. Bleach and another chemicals did improve the situation somewhat, but since there needs to be no other nearby homes with the fungus in order to give your home a chance of it not returning, your fix is probably very temporary.
    Although it is possible that too much pressure was used, if the guy had any knowledge of how to improve the roof, that is probably not why there is uneven color on your roof. I truly hope I am wrong and your roof stays nice, but I do not believe those doing such jobs make such a promise. Good luck.
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Ed Wicks wrote:

I'd leave it alone for a couple of months to see if the uniform discolor returns (soot in the air, etc., which is why you shouldn't have light-colored shingles).
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He probably washed away five or ten years of life too. You could try a cleaner and hose, but that is a crap shoot. It also depends on why the roof is darkened to begin with. Since you'll probably be getting a new roof in a year or two, get a dark color.
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It's difficult to answer your question correctly if you haven't identified what the dark spots are?
If they are bald shingles, caused by pressure washing, then it's time to re-shingle. If it's black algae, fungus, or moss........ http://www.sprayandforget.com /
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Thanks for all responses/help. I will ponder the advice and decide what to do. Ed
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