Secrets of bright work

Rejuvenating old wood or preparing the new, John Tylor gathers advice from experts.

Keeping the love of our life looking beautiful is just one of the pleasures of owning a wooden or classic boat and there are few better places to share this joy than at the annual wooden boat shows with like-minded others.

Last October I attended the Sydney Classic and Wooden Boat festival to learn more about preserving timber. When I saw the exquisite boats, many that have (so far) out lived me, I thought here is expertise worth inquiring into.

Everyone who has external timber knows it needs constant care to survive the Australian sun. The purpose of any coating is to firstly provide protection for the timber and then to improve its look. What you choose to protect your timber with will depend on the type of wood you are protecting and the look you want to achieve; each coating has its benefits and drawbacks.

Sunlight and mould destroy timber by breaking down its fibres. While some high-resin woods fare better than those without this natural protection, the elements eventually win.

A selection of finishes

Today we have a choice of products, each with its strengths and weaknesses. Modern high technology coatings (reaction lacquers) are usually two or three part mixtures that set to a high gloss. They set extremely hard, are resilient and, if applied properly, last for years. Next we have the one part 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.

At the boat show I saw many examples of superb timber work using each of these methods. While some shone like polished glass, others had scope for improvement. From personal experience it is quite dispiriting to slave for weeks to see that the final result is far below the standard I had hoped for, or worse, have it all crack and peel before time. To improve my skills I spoke to several owners and builders. They were generous with their time and advice and here is a short summary of what some of them shared.

Andrew Denman

Andrew is a qualified wooden boat builder from Kettering Tasmania. His business was established in 2005 and specialises in the construction and repair of wooden boats using both traditional and modern construction methods and materials. His work ranges from small clinker dinghies to ocean going cruising vessels. You can find him at: www.denmanmarine.com.au.

With new wood, either a new boat or on a repair, Andrew prefers Altex single part varnish; it is flexible so it does not crack as the wood expands and contracts. He always applies the first coat diluted 1:1 with turps. As many of his boats are clinker and nailed he sprays it on to reduce runs, which is difficult to avoid with screw or nail heads and sharp corners.

In cooler conditions he uses a fast-drying enamel thinner and Altex Quick Dry Additive to halve the drying time. After that initial 1:1 coat he adds four more without sanding.

At this stage he rubs the surface back and applies another two coats. The surface is then sanded back to what he calls ‘white out’ (no shiny patches). These last coats receive a light rub back with 240 grit or a 3M Scotch bright pad in between each coat. He prefers the Scotch bright pad (which he buys by the metre) as it clogs less and is gentler on edges.

In warmer conditions he uses turpentine. as it is slower drying, allowing the varnish time to level out. In really hot conditions, he adds Penetrol to maintain a “wet edge”.

When he is applying the varnish by hand, he uses the ‘roll and tip’ method using high density foam rollers and brushes.

Many of the boats he builds are finished in oil. On the initial coat he soaks the wood with oil, wiping the excess off after 15 to 20 minutes. Next day, when the surface has dried, he applies another coat and then as many coats as needed. One mix he makes for himself is one part of spar varnish, two parts of boiled linseed oil and three parts of pure gum turpentine with a dash of mould inhibitor.

One other owner also gave me his oil recipe: one part tung oil or linseed oil (boiled or raw); one part white spirit or gum turpentine and one part clear commercial timber preservative as used for timber decks. On hard timbers add more turps and on softer timbers increase the ratio of oil.

And here is another one from a friend: flood the raw timber with a 1:1 mix of linseed oil and turps then after a few days, when it is dry, apply the single part varnish. He claims the varnish sticks better (I have not tried this). After this stage he then paints the varnish on as usual.

Dave Pagano

Dave is a spray painter from Penrith, a suburb of western Sydney. In 1998 Dave bought the 5.8m powerboat Cassata, built in Italy by the Lake Como firm Abbate in 1958. It had lain in a garage unused for 34 years before being discovered by Dave.

He achieved the mirror shine on the mahogany by putting on more than 10 coats of Protec, a super clear acrylic automotive lacquer. In his words he “sprayed on the initial five or six coats then rubbed back with 600 wet and dry. After another five or six coats, another rub back with 1200 wet and dry before the final coat”.

After this had set, he buffed it to a mirror shine. He can be contacted on 0413 766 501.

Gino Coia

‘Count’ Gino owns Monte Cristo, a timber 16m wheelhouse ketch designed and built by Ray Kemp. Monte Cristo, built of Huon Pine planks over a Red Gum frame, is moored on Sydney Harbour. Gino is a retired shipwright and uses his skills to maintain his ship.

Every two to three months he prepares the varnish on his wheelhouse with a deglossing primer “I am too old to sand all that timber”.

He then adds one coat of single part varnish. Over time this has built a substantial thickness that provides excellent protection for the timber.

He has a good quality brush with long soft bristles used exclusively for varnishing. His advice is to choose a warm day that is not too hot and lay on enough varnish to flow, but not enough to run. If you do get a run or miss a small section, do not go back to correct it, wait for it to dry and then, if it is still visible, lightly sand and recoat the area.

For his deck, Gino uses oil and recoats this every two or three months or “whenever I have the inclination”. He uses any deck oil he can find in the local hardware shop and usually buys on price, he has never had a failure.

Dave Giddings

Dave is the owner of Drive Marine Services of Beverly Hills, Sydney. His company sells a range of products manufactured by Australian Company Boat Craft Pacific Brisbane.

Bote-Cote is an epoxy product from Boat Craft. Being flexible it moves with the wood and is intended to provide a waterproof base coat layer over bare timber. Dave recommends applying three coats wet on wet. As the epoxy has no ultra-violet resistance it needs a top coat of Aquacote polyurethane. This is water soluble so there is no overpowering chemical smell.

Use a roller, good quality foam brushes or spray, Dave claims spraying gives a better finish than a conventional brush, to lay on several thin coats.

If you insist on using a bristle 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.

Polyurethane dries quickly so do not go back over previous work, just be sure to cover it next coat; extra coats can be added up to four hours after the previous one has dried.

After six hours, or if you want a particularly smooth surface before the final coat, rub with fine wet and dry. In the right conditions you should be able to apply three or four coats in a day.

Rinse the brush or roller in water every 30 minutes to keep it pliable and clean up with soapy water after you have finished.

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. Dave provides a detailed tip sheet to guide first time users as it is totally different to using solvent based coatings. There is also good information on their website: www.BoatCraftnsw.com.au and they are happy for customers to telephone for advice.

General do’s and don’t s

Every specialist supplier, craftsman, boat owner and friend has their own secret formula or method of keeping their timber how they want it. Here are some additional tips, tricks and information on a subject that is not as difficult as may first appear.

What ever else is stated, there is one rule that is inviolate; before you start make sure the timber is dry. More of a challenge with old wood, especially if it has been in the open for too long.

Epoxy resins stick to timber better, are more flexible and have greater mechanical strength. Polyurethanes are generally more UV resistant and perform better as protective coatings. Many of the polyurethane lacquers harden to a glassy surface but they can be brittle and so if there is movement in the timber (particularly at joints) it can crack allowing moisture into the timber.

Single part evaporative varnishes are a mix of resins, oils and hardening agents in solution. When painted onto the timber surface the solvents evaporate leaving the resins and solids as a protective and decorative coating on the surface. They are generally easy to use and are ready straight from the can. They are flexible, so they can move without cracking as the wood expands and contracts. Modern varnishes flow better than most of the earlier products leaving a superior finish.

The following relates to applying varnish.

If the surface is new, sand the surface smooth. Take time with this step, you cannot improve a rough surface by adding varnish, it will just accent the blemishes.

By going to finer grades of paper, it is possible to produce a glassy finish that is enhanced when the oil or varnish is applied. Fill holes or imperfections with filler that is compatible with the coating, especially if using two-pack polyurethane or epoxy resin; test on a sample if necessary. If the timber has been painted, the varnish is badly damaged, or you are changing from one-part varnish to two-part, then it is best to take the surface back to bare wood and start again. Use a scraper or chemical remover if necessary.

If the surface is basically sound (varnish not cracked or lifting) I remove the oxidised surface with 300 to 400 sandpaper, wash with detergent in hot water and a kitchen scouring pad to remove all wax or oil from the surface and finally rinse with clean water. If there is mildew present I use bleach or a proprietary wood cleaner on a pad or stiff brush to remove all black traces and sterilise the surface, then treat as for new wood.

Be sure the surface is clean and dry before applying the new varnish

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.

Choose the time carefully as weather that is too hot and dry will produce a lumpy surface; too humid or too cold will retard the setting time. Be wary when painting in direct sunlight as even on a relatively cool day the surface temperature can rise too high; if the surface is warm to touch, it is probably too hot for optimum results.

If it is a bright sunny day either varnish early after the surface moisture has evaporated, or provide a shade over the working area. Read the notes on the can, many varnishes have a time when it is possible to recoat without rubbing back. This can be as soon as two hours with reaction lacquers or as much as one to three days for one part varnishes.

The relative humidity will affect drying time and quality of the finish. Generally above 85 per cent relative humidity will produce poor results. Polyurethane products work best when the relative humidity is less than 70 per cent as some curing agents can react with moisture giving a misty white surface.

Oil surfaces

Of all the options oils provide the lowest UV protection. They are easy to apply and, once you have built up sufficient thickness, will provide protection provided the surface is recoated regularly. How often depends on the environment and use but, in general, a new coat is required every few months to maintain an adequate level of protection. Add another coat when water does not bead on the surface.

There are many formulations available generally based on tung or linseed oils. Tung oil is extracted from the Tung tree nut and does not yellow or darken like linseed oil and discourages rot and mildew. It dries to a flexible relatively hard surface. Linseed oil has similar properties as tung but, in its raw state, it is slow drying remaining sticky.

Boiled linseed is not strictly boiled but has other additives to make it dry quicker. It has poor weathering properties and does not suppress mould and mildew. I have used it inside the cabin in a mix of turpentine and bees wax by warming the liquid just enough to melt the wax. It provided a beautiful soft satin finish. I used it outside once, but it lasted only a few weeks.

I now use hardware store deck oil; it lasts for months, is cheap and is quick to apply with rag, roller or brush and it does not show brush marks so requires a low level of skill to apply.

Do not catch fire

What ever you do, remember that oils oxidise and this generates heat. Dispose of all rags as soon as they are finished with; do not keep them on board as they can burst into flame. This is a serious issue, I had an oily rag do just that. The weather was hot, the humidity high and it happened in seconds while I was holding the rag. Flames appeared and it produced a lot of smoke, becoming too hot to hold in seconds.

When I opened it out the reaction stopped instantly. Make sure all rags are soaked in water and spread out before disposal. Putting them into a plastic bag is just about the worst way to dispose of them.

Consider your health and wellbeing

Do not breathe the vapours or dust. While sanding wear a good fitting mask and remove as much dust as possible with damp cloths instead of sweeping. If working inside use a fan or cross ventilation. If possible, wear a respirator.

Be aware of dust on your clothing, this can blow about onto the surface you have just provided with a sticky coating and can also find its way into your lungs.

Be considerate of the person who washes your clothes: use a disposable suit and eye protection. Do not eat or smoke while using any of these products.

Some newer varnishes are low toxicity having few solvents, so are less flammable. Others are water based (both one part as well as reaction types) so thinning and cleanup is safe and easy using fresh water.

Many boat owners choose the convenience of clean gelcoat over the more natural and traditional timber finish. It is true timber can take more effort to keep it looking good, but sitting in its warm glow with good company is certainly one of life’s more pleasant experiences and makes the work all that more worthwhile.