Cetol Marine,the original, wonderful, stuff, contains iron oxide (rust) as UV absorber. Iron oxide is absolutely excellent for UV protection over a wide frequency and for long duration. It imparts a characteristic "rust" color, for some unknown reason, if you build up a lot of coats, and can get quite dark. Some people don't like this, so new formulations of Cetol, "Light" and "clear" and "whatever" are available.
TANSTAAFL, as the great Robert Heinlein used to say: "There ain't no such thing as a free lunch" The great thing about Cetol Marine is it lasts a very long time, especially if you maintain it and fix scrapes and dings right away. The new flavors do not last as long; they can't - they don't have as much UV protection.
Personally, I'd rather be sailing, or drinking at
anchor, than varnishing. =)
Best Regards,
e
.::.