Tank1949, The experts here on iBoats have had this discussion for many years and their general conclusion that the thinning of ANY resin, Poly or Epoxy is not a good idea. Especially Epoxy, but...Poly as well. Poly CAN be thinned with Styrene but it, in itself, is a very non-user friendly chemical and must be used with extreme caution. When thinning is needed, (i.e. very thick poly resin, some MFG's formulas are thicker than others.) Acetone can be used but Styrene is the better of the two. I can certainly assure you and every other iBoats member that Thinning any resin with 200% Acetone is NEVER recommended. 10% would be the maximum recommended by our PRO Members who are "in the business" and work with the MFG's of all these resins.. As I stated previously warming the resin prior to adding the catalyst is the preferred method to lower it's viscosity and thus allowing it to penetrate better. Bottom Line...It's the encapsulation that's most important and not so much the penetration into the wood. The purpose of this forum is to inform the members of the best and most tried and true methods for repairing their boats. The numerous and varied opinions is what makes this the best Restoration Forum on the Internet. No one is inferring that one way is the ONLY way, but...There IS more than one way to Skin a Cat, and experience IS the best Teacher!!! After re-reading your previous post I now understand that you were explicitly referencing Poly and NOT Epoxy but again, the consensus opinion applies to both. As you say, the most important thing from ALL of this is...All wood should have an ample pre-coat of whatever resin is used.:nod::thumb: