When waterproofing plywood stringers,deck and transom and any other parts for that matter, do you put hardener in the resin before you apply it on the first coat? or just when you lay up your first layer of CSM and every coat there after?
You never use resin without the catalyst. Are you referring to poly or epoxy? Poly resin cannot be used as a waterproofer without some glass mat or cloth to accompany it.
Yes. Mix up some resin at the proper 1-2% catalyst ratio, then roll a coat on the surfaces you are going to glass. Let it tack. This keeps the wood from soaking all the resin up from your glass, as well as helping you conform the glass to your surfaces since the tackiness holds it where you put it. Place your glass, then apply the resin with a chip brush, or a roller, or both.