Do you have to prep first? I was thinking of using this for my 2 old picnic tables

Thank you for your question. We apologize for the delay in response. You will need to prepare previously stained or weathered surfaces with Cabot Problem-Solver Wood Cleaner, Wood Brightener or Wood Strippers. On severely weathered surfaces, sanding may be required to completely remove all loose wood fibers. Sincerely, Alex Cabot Customer Support