OK, I have read till my eyes feel like they are gonna bleed and have sprayed a few hundred gallons of water learning my new setup. I decided to do a roof for my neighbor for free to get the practice in. I had a brand new batch of sh come in at work and I made a 55 gallon batch of roof mix. I mixed 18 gallons of sh to the rest water. I didn't add surfactant and think that could be the reason for my problem. I sprayed the roof late in the evening and didn't rinse. The roof was a shingle roof that was quite black but didn't have any moss on it. It was a 6 and 12 pitch so I know I should have used gain but didn't. I didn't have t and wanted to finish before dark. I came by today after work and the roof is still as black as before I sprayed it. It looked to be turning white during application but something is definitely not right. I tried getting pics but the way the house is on a hill I cant get any that show whats up. Mainly wanting opinions on what could have happened and if its ok to put surfactant in a fresh batch and spray again. Thanks for the help.