[vc_row][vc_column][vc_column_text]Photo: Rob Oates, Ballantyne Photography[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column][vc_column_text]There’s nothing quite like the deep wooden glow of a clear, bright finish on a wooden boat. It’s pleasing to the eye and makes the most of fine grain and figured timber. It’s also devilishly difficult to get right, needs care and can be a source of endless frustration. Les Baker from Norglass Paints gives us the good oil on clear finishes.
Clear coatings for timber surfaces go under an assortment of names: varnish, timber oil, lacquer, polyurethane, two-pack, etc. Essentially, you can think of all of these as paints without pigment. Because they dry clear, they allow 100% of the available light through to that lovely wood underneath, and there lies the problem.
Australian sunlight is powerful stuff. Combined with a generally arid climate, the intense glare of UV radiation here gives us the dubious distinction of the highest rate of skin cancer in the world and some major problems with ‘sunburn’ on everything – cars, boats, houses and the front garden, if you forget to water it.
To add to the problem, dark colours (think black cars) get hotter than light ones. Choose a dark timber, or a deep-stain finish and it will ‘cook’ the wood on your boat faster that a light one will. Resinous timbers like teak have a natural defence: oil drawn out of the timber by heat leaves a bleached, powdery residue. This protects the timber underneath by screening out UV radiation. But we like the glowing look of the inner grain, so we sand off that residue and paint it with a clear finish. Result? You guessed it.
When the wood and the finish attached to it get really hot, the lignin/cellulose walls of the timber begin to break down and the varnish layer closest to the wood becomes brittle, accelerating breakdown and sooner or later causing delamination. It’s a familiar sight on old Australian boats and cars. All clear finishes will fail eventually, from the inside out.
Some boat owners (and furniture makers) go with an oil finish. This feeds the timber by replenishing the natural oils damaged by the sun. The catch is, of course, you won’t get that brilliant high, durable shine and you’ll have to scrub off and re-apply the oil finish at depressingly frequent intervals, which can get expensive and time-consuming.[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=”1/3″][vc_single_image image=”1125″ img_size=”300×400″ add_caption=”yes”][/vc_column][vc_column width=”1/3″][vc_single_image image=”1128″ img_size=”medium” add_caption=”yes”][/vc_column][vc_column width=”1/3″][vc_single_image image=”879″ img_size=”300×400″ add_caption=”yes”][/vc_column][vc_column][vc_column_text]Most owners prefer the ‘do it once and do it properly’ approach, using one clear coating or another. A good finish requires a good quality product, but your results are based more on how you apply it than on which product you choose. Often the best intentions get it wrong: so much depends on what the timber is, where it is on the boat and how it is applied. Do the research!
Talk to your paint supplier about the different absorption rates of different timbers (Huon pine, celery top, teak, etc.) and where the finish will be used. Internal fittings like cabinets and tables take far less punishment than open decks and a more forgiving satin finish may be the answer. On high-traffic, high exposure areas, expect to apply as many as eight coats of clear finish to achieve a durable result. The lower part of a door might receive more UV radiation than the top, so you will need more coats there to provide uniform protection.
Don’t skip treating the bottom edge. Take the door off and apply at least one coat of clear finish to seal the wood. Splashes and dampness in this area will cause unsealed wood to swell, which will in turn crack the clear coating and case rapid breakdown.
How you apply the finish is extremely important. You can waste litres of expensive varnish if you’re doing it wrong. Aggressive sanding is rarely called for. Light sanding, washing down and the correct choice of brush application, roller or spray can have dramatic effects on the result. Remember that a hard 90° edge is almost impossible to cover evenly with a brush. Again, take advice from your paint supplier on the right method, as well as the right product.
Sanding between each layer of clear is generally a waste of energy, unless you are using a two-pack product. Fine dust particles trapped in the build-up coats actually help block out UV rays. All single pack air-dried finishes are solvent sensitive to new coats, providing that the next coat is applied within the specified time – read the tin! The only pre-treatment required is a wash down with detergent and clean water to remove airborne contaminants. Allow to dry completely before proceeding.
Check the composition of the finish before you buy it. Cheaper paints and varnishes lack the UV inhibitors and filtering additives that make the premium brands significantly more expensive. No clear finish will last forever in Australian conditions, but given careful application, some will last much longer than others. Many clear finishes mellow into an attractive pale honey-coloured coating, but if you want a water-clear result, look for a product that guarantees that on the label.[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=”1/2″][vc_single_image image=”1127″ img_size=”large” add_caption=”yes”][/vc_column][vc_column width=”1/2″][vc_single_image image=”1126″ img_size=”large” add_caption=”yes”][/vc_column][/vc_row][vc_row][vc_column][vc_column_text]Finally, here’s a great tip for brush care:[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column][vc_single_image image=”1138″ img_size=”full” alignment=”center”][/vc_column][/vc_row]