What it looks like to me is after you mixed your tank you started to spray without your mix being run through the hose. So when vou first started spraying you had just h2o coming out. So the left side got hit with no mix. Need better pics after a rain.
your on the money!! that's what happened. i totally forgot till it was to late.. but it did rain and the rest or the roof looks great.and the business owner is very happy. I'm to finish it up this up coming week.. i will post more pics then. thanks...
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Hogwash Cleaning Solutions llc. Lake George, NY, 12846 518-307-0520