I used Cetol for more than 10 years...
The key to a successful job (like many other things) is prep...and prepping for the first application of Cetol needs to be everything you'd do to varnish--clean the wood and sand it as smooth as a baby's cheek. As is also true of varnish, the wood must be completely dry before applying Cetol...even high humidity can be a problem. Three coats are all you need...each lightly "sanded" with extra-fine bronze wool--to remove any bubbles or bumps--before applying the next coat.I'm usually a stickler for following mfr's instructions...Cetol is an exception. Their instructions call for only wiping down with mineral oil before applying a new coat next year...and IMO, that's what results in a buildup and unappealing increasing opaqueness. I always "sanded" with fine bronze wool before applying a renewal coat...'cuz that removes any scratches, scuffs, ground-in dirt and UV-degraded Cetol. THEN I wiped it down with mineral spirits to remove any dust etc. It's a VERY easy job compared to the cleaning and sanding you have to do the first time or to re-varnish. Then I applied TWO new coats instead of just the one called for in the directions. My boats kept their "first year" look for 10 years.Just my $.02 worth...