Dicor Roof Sealant. Do I need to use the Part 1 Cleaner?

no, Lap sealant is so sticky and gooey that as long as there is no obvious dirt, or a layer of skum it will stick. if you are happy with your soap and water cleaning job then you most likely have cleaned it good enough. I have never prepped a surface with special cleaners, maybe rubbing alcohol, but usually just car wash soap or just windex and it always seals.