Thats not from overlapping, its where the sides are getting cleaner than the middle because the nozzles are over top of that concrete longer. From what I have figrued out it happens either because of having the surfacer under powered or if you are starting to have problems with the surfacer, ie, needs nozzles or bearings. Mine was doing it when my pump was going out and right after I put the new pump on because I hadn't got the unloader adjusted just right yet. Now no striping and its great again.:victory: