i clean it off with de rust wheel on drill ,scuff it up,80 grit,clean with alc.then i use a hard truck bed liner 2-3 coats.made by couple different companies with different textures.i also strain out the rocks if they come to rocky.used to do that on jeep wrangler hardtops,like a rhino lining,never chipped once,long as you scuff and clean well.thats the important part.good luck