'Varnishing your sailing boat'
Whether you are rejuvenating an old boat, or installing new wood, how you care for the timber on your boat will make all the difference to its appearance. Doing it yourself will add the joy of spending the weekend 'messing about' in the sunshine.
Which kind of coating to use?
The original purpose, of course, of any coating, is to preserve the timber, and, at the same time, improve the way it looks. Each type of coating has advantages and disadvantages
Modern high technology coatings (two-pot or even three-pot) set to a high gloss. They set extremely hard, are resilient and, if applied properly, last for years.
Next are the one pot varnishes (evaporative mixes) that, while not as shiny or hard as the reaction lacquers, provide good protection.
Thirdly is a range of oil-based finishes. Oil coatings do not provide the same protection as varnish, but they can still look beautiful and can be the easiest to maintain. They degrade quickly and, if not replaced frequently, leave the timber to the mercy of the sun.
It is important to understand the strengths and weaknesses of each of these methods before spending much precious labour for a result that you didn't want, that doesn't last as long as you thought, or doesn't look as splendid as you were hoping.
With new wood or wood in good condition, I prefer a single part varnish. Why? Because it looks splendid, lasts relatively long, and can be repaired without too much trouble. However, with this coating, you MUST pay attention within the stipulated time between coats, because once deterioration sets in, you might as well remove the varnish, sand back again, and start afresh.
I always apply the first coat with a 50% turps dilution, which tends to soak that first coat into the grain, adding to its preservative qualities.
After that first coat I apply three more coats without sanding, two hours apart (as long as the air is drying enough for that), then wait three days. Then sand with a minimum of 240 grit sand paper, then three more coats, this time a day apart, rubbed down with a Scotch bright pad in between.
If the timber is not in very good condition, oil may offer the better finish. On the first coat I absolutely soak the wood with oil, wiping the excess off after 15 to 20 minutes.
Next day, when the surface has dried, I apply as many coats as needed. Again there are several mixes that you can use according to the type of timber. If you don't want to use store-supplied deck oil, my favourite, with which I have had a lot of success is one part tung oil; one part white spirit and one part clear commercial timber preservative. Then you vary this according to whether you are applying it to soft or hard timber. The softer the timber, the more oil in the mix.
Oil has the great advantage of, while it needs more attention than varnish, on a more regular basis, it can be patched much more easily, and, if neglected, does not ever get to the stage where you have to sand back to bare wood and start again. Use a low grit sandpaper, because here you want the oil to sink into the timber.
For floors below decks, I favour using an epoxy product. Being flexible it moves with the wood and is intended to provide a waterproof base coat layer over bare timber. Apply three coats wet on wet. As the epoxy has no ultra-violet resistance it needs a top coat of polyurethane, if necessary, but I have never used it above decks.
Use a roller to lay on several thin coats. If you use a brush be careful not to get too much foam into the surface as this clouds the coating. Thin with 10 to 15 per cent of water in warm weather but be aware of runs.
Two coats are adequate, but three to four coats will provide a higher gloss and longer term protection; if you need an even higher shine it can be cut and polished like car duco after it has completely hardened in four to five days.
After three to five years the surface will start to lose its gloss, so lightly sand with a scouring pad and hot soapy water then roll-on two replacement coats.
It's true that every boat owner has their own favoured methods of keeping their timber how they want it, so these have been mine.
Some extra tips:
1. This is so important I repeat it. Make sure that timber is completely dry before you start.
2. Epoxy resins stick to timber better, are more flexible and have greater mechanical strength, so they are ideal for below decks. Polyurethanes are generally more UV resistant and perform better as protective coatings, but they are more brittle, so if there is a lot of movement in the timber, maybe oil will be a better choice.
3. Varnishes look marvellous, are easy to use - straight from the can, are flexible. Just stay on top of the job to avoid too much neglected deterioration. All varnishes need to be applied in sufficient volume so the surface can flow, this allows brush marks to level out. But be careful on vertical surfaces. Several thin coats are preferable to one overly thick coat as it allows the surface to harden.
4. Oils provide the lowest UV cover, but they are so easy and forgiving to apply that they become a pleasure. However, they don't last as long as well-applied varnish, so need more attention, more often.
3. Sanding: No kind of coating (oil is the best though) looks good on a rough surface. Start sanding with a low grit and work your way up. Varnish or expoxy is best with the final sanding of the bare wood to be with no less than 240grit, as this seals the timber.
4. Choose the best weather. Weather too dry will tend to make the result lumpy, to humid will put unwanted moisture into the mix, and too cold will make it take much longer to dry. Don't forget to wait until any dew has disappeared and the sun has dried the surfaces.
5. Wear a mask when sanding. Fine timber particles have been known to cause serious health problems.
...and if all these seems too hard, then stay away from timber on your boat!
by Lisa Mylchreest
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12:56 AM Sat 30 Jun 2012GMT
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