Should I sand the deck first before applying this? We have really bad splinters in a deck that’s only 2 years old. Has never been treated.

Thank you for your question. We apologize for the delay in response. Yes sanding would be best in order to completely remove all loose wood fibers. Fill larger cracks with an exterior wood filler Be sure surface is free of all dirt, mildew stains, loose wood fibers and other foreign matter. In order to be effective, a stain must be able to penetrate. Sincerely, Alex Cabot Customer Support