Instructions for the primer are here.
proflex-primerIt is a coating and has to still be tacky when the Liquid Roof is applied. Instructions say-"Still tacky but does not stick to your shoes"
However it is only required on EDPM rubber that has had another coating applied. (Like going over top of a "Kool Seal' coating) or if you have an "Alpha" brand rubber roof. I applied LiquidRoof to my prior motorhome, it looked good and held up well.
Liquid Roof:
They recommend you use 1/2inch electric drill, and I agree. It is a 2 part product and needs to be mixed thoroughly. Once you start mixing it's too late to discover you need a bigger drill.. It does have a working life but any left over can be refrigerated for use the next day.
I think one of the other coatings (Dicor??) that are available uses a cleaner/primer and power wash prep.
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Just re-read your 1st post, if your travel trailer does not have a rubber roof, you will need the primer....
