Starting from Scratch—A Varnish Transformation - SailNet Community
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Starting from Scratch—A Varnish Transformation

Intensely sunny days like those we found in Venezuela mean that without a religious regimen of varnishing, eventually a stripping job is in the cards.
It's hard to pin point exactly what it is about a well varnished piece of wood that strikes the chord of beauty in us that it does. Part of it might be the wood itself, a piece of teak or mahogany from half way around the world shaped by a knowledgeable hand some decades ago, the way the grain flows, or the glint of the sun off the wood and the varnish, the union of natural and man made elements; something protected, yet still on display for all to see.

Whatever the poetry existant in varnished marine hardwoods, there is no shortcut on the long journey to the point where you can wistfully gaze at it. As with so many other boat projects, the magic is all in the prep work. Our 1964 boat has had varnished mahogany cabin top for its long life, and after our time cruising in the strong light of the tropics followed by the abrupt and time compressed transition to shore side living, varnish concerns fell to the bottom of the list. The 10 coats of varnish we'd been religious about keeping up with while cruising eventually started chipping and peeling away, leaving bare wood. It was time for a varnish intervention.

"The 10 coats of varnish we'd been religious about keeping up with while cruising eventually started chipping and peeling away, leaving bare wood. It was time for a varnish intervention. "
With a deep breath, the transformation began. First all the hardware came off, dodger snaps and cleats. Then came the stripping. We'd used a heat gun and scrapers in the past, but this go-around we found a Jabsco paint and varnish remover to be the most time effective technique. You'll want to apply this carefully, making sure it doesn't drip on anything you don't want removed inadvertently, like your fingerprints. Apply the stripper and move onsome kind of evaporating takes place that lifts the varnish, reapplying more over it interrupts the process. Once the stripper has done its bubbling magic (20 minutes or so), take a sharp scraper and carefully pull back the layers of varnish. Keep in mind that these curls can still eat through paint. Once the varnish was up, we began sanding.

The bubbling to the right is the old varnish magically peeling up. There's plenty of sanding to come.
The last time we did a major stripping job like this we used both an orbital sander and a finish sander and learned some lessons the hard way. At the end of our labors, we were left with little squiggles in the cabin top buried beneath several layers of varnishprobably not visible to any eyes but our ownbut imperfection that were noticed enough over the years that this go-around we wanted to avoid leaving these marks. This time we still used our sanders, but followed them with a hand sanding of the same grit sandpaper to iron out any of the squiggles they had left behind. We started with 80-grit sandpaper on the orbital sander to take the bulk of the varnish off. Then followed that by hand sanding with 80-grit on a sanding block. We repeated the process with 120-grit. First the orbital, then by hand with a sanding block. Finally we hand sanded with 180 to leave the Mahogany as smooth as possible for the first coat of varnish. Having a shop vacuum nearby helps keep varnish bits from flying onto your neighbor's boat, being able to hook the vacuum hose up to the sander is even better, and a dust mask is a good idea.

Water had found its way into the wood in a few spots, most notably around screws and snaps for the dodger where the caulk for such fasteners had either not been applied enough or which had broken down over time. In some places the water stains were sanded out while removing the old varnish. In one or two more serious cases we drilled weakened wood out and put a plug in to replace the damaged wood. For really dark stains, try oxalic acid to bleach the wood back to something of its original color.

Over the hump, sort of. Lightly hand sanding after the second coat of varnish and application of stain. Eight more coats to go.
The original plan of being able to sand and get stain and varnish on both sides of the boat in a weekend was abandoned somewhere around Saturday afternoon for the more realistic goal of just completing one side. Once all the varnish is off wood, it's vulnerable to water getting in the grain. You don't want to sand varnish off with out promptly recovering the wood. We'd had a number of very dewy nights before this project started and didn't want to waste the morning waiting for the wood to dry, so opted to wrap the boat up in plastic wrap in an attempt to keep the moisture content down. A good weather forecast is important for the best varnishing results, wind whips up dust and blows varnish off the brush and all over everything else. Rain is obviously bad. Temperatures that are too cold will have you wondering when the varnish will ever dry, too hot and bubbles will form in the finish.

Sunday saw a final hand sanding with 180 and a close look at any blemishes that had escaped our scrutiny. Then it was time to thoroughly vacuum the surrounding area, wipe up all dust with a rag dampened in mineral spirits that could blow into the varnish, and get ready to stain. First came the taping of the deck, around window trim, and electrical cord outlets. Our boat's mahogany is a rich red color due in part to the stain. This was applied with a rag and also thinned with paint thinner. Straight out of the can the stain looked too dark and too much like paint. Thinned, the color lightened to show the wood beneath.

You may not be the only ones to admire the handiworkdolphins off the bow.
Once the stain was dry it was finally time to varnish. The first coat of varnish is the thinnest. It should be thinned with varnish thinner to 50 percent. This allows the varnish to penetrate the grain and act as a sealer, but also means that just a little goes a long way. Start at one end and work toward the other, with minimal overlapping brush strokes, but still not leaving any holidays. We prefer throw-away foam brushes. Once you're done, wait for the varnish to dry completely. The first coat is likely so thin that no sanding is needed. Once this dries, apply the second coat, thinning it 25 percent or so. After this dries, sand very lightly with 220-grit sandpaper, just scuffing the varnish enough to give the next layer a good grip. Keep repeating the process until you've built up enough layers to protect both the beautiful wood and all your hard work. Ten is good, 12 is better. Don't leave the tape on for more than a day or two. Having to re-tape is a pain, but having to clean up an unsightly gummy mess a week later and then re-tape over it while your neighbors give you that I-told-you-so look adds insult to injury. Now take a solemn oath to never let your varnish go this long this neglected, and treat yourself to a sail to wherever your boat will be ogled over.

Mark Matthews is offline  

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