A text by Uwe Baykowski
In English-speaking countries, skippers say "brightwork" when they mean the paint surface of a yacht. And they express so much more than the German term can say. "Bright" means "radiant" and "shiny", meaning "luminous" and "bright"; it makes you want to smell the honey-coloured tincture and feel the sticky sensation of the brush in your hand. "Brightwork" is a commitment to making the beloved ship shine again in spring, and it expresses the hope of achieving this as perfectly as possible.
Once the owner is on board before the start of the season, humility quickly joins the canon of spring fever. Because it's not that simple. Even old woodworms admit behind closed doors that they have failed at painting before. The spring sun was already warm and masked the cold ship. Or it got bitterly cold at night. Someone opened the large hall door and dust swirled around. The air was more humid than expected, or there were unnoticed crumbs in the paint or brushes. There are many ways to achieve a brilliant result, but only one way to get there. Nothing can go wrong.
In addition to the pleasure that a flawless surface provides when the paint job is successful, the colour structure also has very tangible functions. The clear coats in the above-water area for the hull, deck timbers, superstructures, hatches, masts and spars are primarily intended to protect the wood from embrittlement, discolouration and openings in glued seams. The colour coatings for the underwater area prevent excessive moisture absorption and rotting. Antifouling repels smallpox and mussel infestation. Finally, the coloured high-gloss paint on the freeboard gives the yacht a personal touch and prevents the wood from drying out and absorbing water. Achieving all of this is not rocket science.
The products
Various systems with different properties are available for the respective colour structure. They are categorised according to the degree of final hardness. A distinction is made between wood oils, alkyd resin varnishes, polyurethane varnishes, two-component varnishes and coloured varnishes.
Wood oils have the advantage over other varnishes that they penetrate deep into the wood and are much more elastic. There is less risk of the coating cracking or flaking; however, longer drying times must be expected. The most famous oil is probably linseed oil, which is obtained from linseed. Very good results have been achieved with products containing linseed oil. Another product containing linseed oil is the good old red lead red lead, which has, however, been withdrawn from the market due to its harmful effects. For decades, red lead paint was used to preserve wood and steel in yacht building as well as in commercial shipping. It is still available to specialised companies. It should not be replaced by the synthetic resin red lead available to everyone.
Products that are commonly referred to as "boat varnish" are usually based on alkyd resin. Although these varnishes are harder than oils, they still have a very elastic consistency. In recent years, however, they have experienced increasing difficulties with the stronger UV exposure caused by sunlight. In many cases, the incorporated UV filters cannot prevent the formation of unstructured, very fine hairline cracks on the paint surface. Although the products have not deteriorated, the environmental conditions have. These coatings must therefore be renewed every year to stabilise the UV filter that has been degraded by the sun.polyurethane (PU) coatings and, more recently, monourethane coatings are even harder and more resistant than alkyd resin coatings, and drying times are shorter. Intermediate sanding can therefore be carried out earlier. The PU lacquer sets faster, which can have a detrimental effect on the levelling and brush strokes remain visible. The aforementioned craquelure can also occur here.
Two-component paints and even three-component paints are the hardest and most resistant, but also the least elastic. There is a very high risk of cracking on wooden parts that are subject to heavy use, such as frame joints on superstructures or older glued joints. These paints also set very quickly and may only be used at certain temperatures and humidity levels. Achieving a good result with a brush finish is therefore difficult, but not impossible. However, excellent and above all more durable results can be achieved with spray paints than with single-component paints.
Coloured varnishes, which are used for the outer skin, waterline, cabin roof and other areas, are also based on alkyd resin or polyurethane; coloured oil varnishes are only rarely used. Due to their pigmentation, coloured varnishes are much more UV-resistant than their "clear counterparts". Some outer skins only need to be repainted every two or three years and not every season, as is essential with single-component clear coats. Polyurethane-based coloured paints are also somewhat more sensitive to the cold during application.
The underwater hull
If an underwater hull is to be completely stripped and rebuilt, the hull must be inspected for defects before preservation. Rotten wood should be replaced and corroded metal parts renewed if possible.
It is advisable to impregnate the hull with a fungicide to protect it from rotting. This is followed by a coat of chlorinated rubber primer. Here too, there are other systems; and many owners of classic boats swear by preserving with linseed oil - the decision is often more of a philosophical one.
More on the topic of care:
If you want to smooth the hull by filling, you should do this after the first primer coat, as the unevenness is now easier to recognise. However, it would be even better to sand the fuselage so smooth that you can do without filler. You should never try to close fine plank seams with a two-component filler because it will be too hard. It is better to use a soft paint filler, which dries slowly but never becomes completely hard. Window putty, made "slim" with linseed oil, is also suitable for this purpose. After filling, apply three more coats of primer, followed by the antifouling coat.
Metal parts
This mainly concerns the troublesome cast iron ballast keel and the iron bracings in the ship, such as floor cradles or steel frames in composite constructions. The ideal solution would be to coat the ballast with epoxy from the outside or to dismantle, blast and galvanise steel bracing. Unfortunately, the effort involved in the latter case is usually too great. For this reason, preservation is carried out in situ using oils or red lead. Before conservation, the metal parts should be derusted as well as possible. This can be done with a simple steel brush or, if possible, with a plait brush on the Flex. The market offers various products for preservation.
The bilge
Steel ships or moulded hulls can also be coated with modern varnishes in the bilge area. However, this would not make sense for conventionally planned classic yachts, whose wooden hulls always have a moisture content of over 15 per cent in the bilge area. Oils are used here. The moisture can then escape and the hull can breathe. For this to work, the bilge must always be well ventilated. In a permanently wet or humid climate, even the best preservation cannot withstand a fungal attack with subsequent rotting.
The surface ship
New owners of classic yachts in particular always feel the irresistible urge to strip the underwater hull or even the above-water hull in order to see the condition of the wooden planks in their true beauty. There is often a desire to reapply clear varnish to a colour-painted hull, which often leads to disappointment because the wood of the above-water hull is not as beautiful as expected or there are many black spots on the rivet or screw connections that detract from the overall appearance. Nevertheless, in many cases it makes sense to remove old layers of paint and tackle this tedious and energy-sapping task.
Some companies offer the gentle sandblasting of wooden hulls. There are two methods for DIY work: Scraping or stripping. The latter usually causes a terrible mess. In addition, most paint strippers only work properly at temperatures above 15 degrees. Sanding doesn't work either, because the antifouling hopelessly clogs up even the best sandpaper. Scrapers with hardened blades are best suited for working on the underwater hull because extremely hard primer layers can lie under the antifouling. You should refrain from using a heat gun on the underwater hull because toxic gases are produced when the paint burns. In any case, even when scraping and sanding, a respirator must be used during these activities.
Before all layers of paint have been finally removed, the position of the water pass should be secured by small nail points or punctures with a pointed drill at a distance of approx. 0.5 to 1 metre. Once the thickest layers of paint have been removed by scraping and only a few thin residues remain on the outer skin, sanding can take place. Machine aids can be used safely in the underwater area. Random orbital sanders with external extractors are best suited. Machines with integrated extractors tend to disperse the sanding dust in the environment or on the sanding surface.
Even if the underwater hull does not have to be as smooth as the freeboard, you should make an effort to achieve a nice surface without holes and dents. The layers of paint on the freeboard can be easily removed using a hot air gun. A "yacht scraper" is recommended for scraping. It is important that the blade is not too thin; otherwise it will flutter during the work and leave ugly grooves in the wood. Sanding the freeboard, whether it is varnished or coloured, is something for experts. The shinier the surface becomes during varnishing, the more visible the unevenness will be.
The surface can be lightly pre-sanded with a random orbital sander to remove the last layers of paint. However, fine sanding should always be done by hand with a sanding board, preferably first in a diagonal direction and then in a longitudinal direction. Initially, coarse sandpaper, such as 80 grit, should be used, then progressively finer sandpaper up to 120 or 150 grit, and even up to 240 grit for natural finishes.
Painting coloured boat hulls
In the case of coloured hulls, the aim should be to dispense with filler completely. However, slightly open plank seams are filled with soft paint filler.
Once you have decided on a colour system, whether one- or two-component, you should stick to this system from the primer to the final coat; this also applies to the thinners. The primer coats, approximately two to four depending on the absorbency of the wood, can be applied with a good foam roller. If the specified recoating intervals are adhered to, no intermediate sanding is necessary. However, if filler is required, it should be applied after the first primer coat. After priming, intermediate sanding must be carried out, which can now be done using a machine with a very fine grit, such as 320 grit. The risk of sanding dents into the surface is no longer so great. The first coat of paint can now be applied - one coat is not usually enough.
The varnishes can also be applied with a foam roller and smoothed with a foam brush. The flow of the paint surface depends primarily on the product itself and the processing conditions. One-component paints can be made more flowable at low temperatures with a dash of Owatrol oil. Two-component paints can also be thinned, but only the specified product may be used. Two-component paints should not be applied if the ambient temperature is less than 10 degrees.
Varnishing natural hulls
If a hull is to be stained before the first coat of varnish, it is advisable to moisten the wooden surface with a wet sponge. This causes the softer pores to swell and stand up when drying, the surface is now rough again. This effect would also have occurred after applying the stain, but the first coat of varnish would now have been applied to a rough surface.
After soaking, the surface is sanded again very finely, then it can be stained and finally varnished, again with a foam roller and foam brush. This procedure is best carried out by two people. Follow the paint manufacturer's instructions regarding thinning. The first thinned coats of varnish can be applied without intermediate sanding within the specified intervals, after which intermediate sanding should be carried out.
Many owners of classic boats swear by 400-grit wet sanding before final varnishing; however, 320-grit machine sanding is sufficient. If the surface is flawless, rubbing with a sanding pad is also sufficient. The most important and most difficult thing to achieve an optimum result is to remove all dust before applying the final coat. The surfaces should be vacuumed with a good hoover and brush and wiped with a clean cloth, for example with white spirit. The surface should then be rubbed down again with a dust-binding cloth.
The area around the boat should also be reasonably clean. Draughts must be avoided at all costs and painting should not be carried out on stormy days. Despite following these rules, even professional yacht painters often despair because the painted surfaces - especially the horizontal ones - contain dust particles. To reassure you, it should be said that none of this is visible in the water. A single-component paint should have at least eight to ten coats. When sanding between coats, care must be taken not to sand too hard, especially on curves, so as not to accidentally remove the coating thickness again.
The renewal of natural finishes
Single-component natural coatings must be renewed annually to stabilise the UV protection. There have been many unpleasant surprises when varnishing has not been carried out for a year. After cleaning with clear water, it is usually sufficient to sand the surfaces with fine paper, such as 320 grit. However, if there are areas down to the bare wood or infiltrations of moisture, these areas should be sanded down to the wood and selectively built up with varnish in around five to eight coats. It is advisable to treat these areas before sanding through all the surfaces, as they will be difficult to spot afterwards. If you want to sand the entire surface beforehand, these areas should be marked.
Masking
Before applying tape to freshly painted sections to separate surfaces for painting, you should make sure that the paint has hardened sufficiently. Otherwise, the fresh paint may be removed when the tape is torn off. Particularly outdoors, make sure that the tapes do not remain on the surfaces for too long - otherwise you could have difficulty removing them again.
The guarantee of success: what to look out for when painting
- Carefully study the processing recommendations of the paint
- Filter paint from the previous year to avoid contamination
- For the same reason, always paint from a separate container - not from the tin. Do not wipe the brush on the edge
- The best results are achieved with high-quality brushes
- Drag new brushes over sandpaper to remove loose hairs
- Wipe the surface with dust control cloths immediately before painting
- Paint large areas with a roller and blend with a brush
- Pay attention to the temperature of the air and the material to be painted
- The air should be as dust-free as possible and exchanged - but draught-free
- Avoid humidity above 80 per cent
- Keep the brush hanging in turpentine substitute for the next day's work. Before taking longer breaks, wash out with brush cleaner until the paint is completely removed, then with soapy water. Dry hanging
- Intermediate sanding removes annoying dust inclusions
- Use high-quality adhesive tape. It is torsion-resistant, does not leak and can be removed without leaving any residue
