Varnish questions

[esingleman]

Alright, my little boat is seven years old this year and for the first time I have some old varnish peeling in a few spots. Here's what I did: seven years ago I originally put down four coats of Epifanes wood finish then final coat of their regular gloss. As a side note I found Epifanes varnish did not level out very well, and left orange peel like dimples (thinning didn't seem to help). For the next three years I sanded with 220 grit and reapplied a new coat of Epifanes gloss. When I ran out of Epi, the next year I switched to Interlux Schooner, and I like it much better (levels out very nicely). Year six I neglected to revarnish.

So is my peeling this spring because I didn't varnish last year, or is my brightwork due to be completely sanded down to bare wood, or is that ever necessary?
The boat is covered when not in use during the season, and is turned upside down and covered during the winter, so it doesn't get too much sun exposure.

One last thought is that maybe the peeling is because I didn't sand well enough in those areas before the last coat. I will check to see if there is varnish under the peel or bare wood.

Last question: I switched this year to Z-spar Captain's Varnish (on the advice of Dave Corcoran, God rest his soul) and tried it on my transom. Really flows out well, but the stuff looks weird in that it is a light pink color in the can (or in a white container I should say). Does this stuff have enough UV blocker in it? I though the UV block addative was merely rust powder in many cases, that's what gives the amber color of most varnishes.

[Lew Barrett]

The usual rule of thumb with varnish is eight coats for the basic build, then two per season. Another rule of thumb is "don't bother doing one coat, always do two refresher coats."

Without knowing how you went about sanding, how you sealed in your first coat, the if you waited weeks after sanding to apply a coat or applied immediatly after sanding, how you may have thinned and with what, and a variety of other variables, it's hard to say why your varnish is sheeting off. If the base is fundamentally good, I'd bleach any bare spots, seal them and varnish over the rest assuming the bulk of what is there is in good shape. It's amazing how poor an old base can look and still be saved for another season as long as you want to use your boat and not show it.

[esingleman]

My first coat was 50% varnish and 50% mineral sprits, and the next coat 75/25, then the rest about 100%, some were thinned a little to try toget rid of the orange peel. Seasonal coats were sanded with 220 just to rough up the surface not to remove layers, and were applied right after sanding and cleaning with a tack cloth. And I do think I applied two coats each season now that I think about it (within 48 hours w/o resanding).

[Lew Barrett]

My first coat was 50% varnish and 50% mineral sprits, and the next coat 75/25, then the rest about 100%, some were thinned a little to try toget rid of the orange peel. Seasonal coats were sanded with 220 just to rough up the surface not to remove layers, and were applied right after sanding and cleaning with a tack cloth. And I do think I applied two coats each season now that I think about it (within 48 hours w/o resanding).

Without re-sanding but within 48 hours is a prescription for peeling with most long oil varnishes. Sanding really needs to be done to an even white. Anything you don't key won't hold. The orange peel should have been sanded out, then the rest of it should have flowed in flat. That's been my experience with Epifanes; it will flow and lay down.

[esingleman]

Okay, I have examined under the peel and it is down to bare wood. So my thought is that in these areas, I must have sanded down too far at some point and never built up enough layers above to protect the wood surface from UV damage. Or, I sanded too far down (like to base wood), and didn't thin the first repair coat enough to seal (absorb into) the wood.

[Lew Barrett]

Sounds reasonable, with the added comment that you need to build sufficient film thickness (eight coats from raw). That, more than the amount of thinner would be my guess.
Sand between coats. Added: Sand between coats that is, if you are not using a product that allows you to overcoat without sanding within a specified period of time. Alternately, you can hot coat, which means the following coat can go on while the first coat is still tacky. But for a new varnisher, following the basic rules, that is, sanding, coating, allowing for cure, then repeating is the best course. As you have learned, you never want to blow through to the raw wood, so be thorough, but gentle on those first coats.