Despite what others say, this is great hard primer that has good sanding characteristics and coverage. The only drawbacks are that it is finicky with weather (either direct sun or wind) ... and one has to use some trial and error to get the brushing liquid ratio correct for given conditions. I found that rolling only worked ... the primer didn't like to be tipped with a brush at all. Also, square foot coverage varies with the surface ... ie: prepped fiberglass surface was porous and took nearly double the amount recommended. 2nd coat of primer covered adequately to the stated coverage amount. Found that rolling on 34' sailboat hull vertically is not the same as the YouTube instructional videos that only show rolling & tipping on small tenders. The product rolled well vertically w/o having to roll horizontally - - - with given conditions be careful of drips and roll in easily managed "panels" less than 18" in width. Don't apply in direct sun. Do apply in conditions less than 70F or so.