The spring weather has definitely taken a turn for the better. Yesterday and today the temperature has risen to 14 degrees Celsius and the skies have been clear of cloud. There’s been rather too much wind for varnishing, but waiting for ideal conditions could take weeks. I’m not fastidious about achieving absolute perfection, but I’ll settle for a reasonable finish which protects the underlying wood. The truth is I prefer paint to varnish because it so much easier to maintain, but to paint Bumper’s spars would be sacrilege and when it comes to selling her, I doubt she would be so appealing to a prospective buyer.
If I were to tackle varnishing to perfection I would not only need to strip off all the previous varnish very carefully, but I would have to get rid of the black stains by using a bleach of some sort. It has been said that 50 minutes of every hour re-varnishing should be spent sanding and the remaining 10 minutes actually applying the varnish. All sanding should be done by hand, not by machine, as the latter can damage the wood’s surface.
For continuity, the same type of varnish should be used, either an alkyd, polyurethane or a phenolic. The alkyd is the cheapest, but not as tough as the others, and the two-part urethane has the highest resistance to abrasion, as well as the longest gloss retention. The phenolic type is the traditional varnish - much the preferred choice for spars liable to torsion, owing to its excellent flexibility. Varnishes have varying degrees of ultra violet protection and give wood a golden lustrous glow, but very pale woods tend to turn yellow - that’s where a preparatory stain can be beneficial.
If you’re starting to varnish directly on newly prepared wood, it’s a good idea to follow the instructions which usually advise diluting it by adding 15 percent of the appropriate thinners. This facilitates good penetration into the wood for better protection and subsequent adhesion of the next undiluted layer of varnish. Some people give this a light sanding to remove the ‘stubble’ that occurs after the first application. Perfectionists wet and dry each coat very lightly with the finest emery paper until the final layer. A minimum of three coats should be applied, but for the very best result it may necessary to apply 6 to 8 layers.
Remember to sand with the grain and use a vacuum cleaner to remove the dust, then a finely woven rag saturated with paint thinners or alcohol to ensure the surface is entirely dust free. I’ve been told top craftsmen use disposable strainers and paper paint buckets and never stir their varnish, but I don’t emulated their absolute perfection. Good application is achieved through practice, but it’s better to not to overload a brush and to apply the varnish with even ‘pulling’ strokes. Never try removing surplus varnish on the side of the can. It’s best to work carefully so as to maintain a ‘wet edge’. Only use a good quality soft brush.
During the sailing season remove any traces of salt and grime with a chamois and fresh water. About halfway through the season apply at least one coat of fresh varnish, and it’s not a bad idea to have a small quantity of varnish aboard for touching up parts that may get damaged.
Although there’s a lot of satisfaction in seeing fine varnish work, remember how much effort goes into achieving it. If you’re the sort of person who likes being on the water more than preparing for it, I would advise you to paint rather than varnish!