“Spring time – painting time”
and we are already at the first difficulties:
Cold and humidity do not make working with modern paints easy for us. The external conditions are similarly bad for most owners of classic yachts, whether in a cold, damp, dusty hall or under the self-built “greenhouse”. Therefore, this article is intended exclusively for the committed amateur, not for the professional who is equipped with high-tech and heated hall with suction system.
Tasks of paints, oils and coatings
The clear lacquers in the above water area for the hull, wood on deck, superstructures, hatches, masts and spars are primarily intended to protect the wood against embrittlement, discoloration and openings from glue seams.
Aesthetics also play a major role here:
The lacquers and oils should emphasize the natural structure and color of the wood and highlight it in a brilliant way.
The color coatings for the underwater area are supposed to protect the wood from too much moisture absorption and thus from rot.
Antifouling protects against smallpox and mussel deposits.
The colored high-gloss finish of the freeboard is intended to give the yacht a personal touch and protect the wood from drying out and water absorption.
Clear coats and oils
We differentiate the products in the order of their final hardness, from wood oil to epoxy coating.
Wood oils have the advantage over varnishes that they penetrate deep into the wood and are much more elastic than the harder varnishes. The risk of tearing and peeling is lower here.
The most famous oil is the linseed oil, which is extracted from linseed.
With products containing linseed oil such as
Le Tonkinois or Biopin have achieved very good results.
A product that also contains linseed oil is the good old red lead, which, however, has been taken off the market for end users because of its health-endangering effects.
Red lead was used for decades to preserve wood and steel in yacht building as well as in commercial shipping. Real red lead is now available again for specialist companies. It should not be replaced by the synthetic resin red lead that is available to everyone.
Important: When using wood oils, longer drying times must always be expected.
Alkyd resin paints:
Almost all products that were previously called “boat varnish” are based on alkyd resin.
The best-known products of these one-component paints include: Epifanes, Schooner, Spinnaker green, Rubbol, Rylard.
These varnishes are harder than the oils, but they are still very elastic. In recent years, however, you have had increasing difficulties with the stronger UV exposure from the sun.
In many cases, the incorporated UV filters cannot prevent the slight formation of unstructured, very fine hairline cracks on the paint surface.
This paintwork has to be renewed every year so that the UV filter that has been degraded by the sun is stabilized again.
There have already been disagreements between shipyards and owners because of this creep, and even up to court cases. At this point it should be mentioned that the paints have definitely not deteriorated, but the environmental conditions.
These lacquers are even harder and more resistant than the alkyd resin lacquers and the drying times are shorter, the intermediate sanding can be carried out earlier.
The PU lacquer picks up faster, which can have a negative effect on the flow: brush strokes may remain visible. The aforementioned creeping can also occur here.
Products: Rylard-PU, spinnaker red, Asuso.
These paints are the hardest and most resistant, but also the least elastic paints. Therefore, careful consideration should be given to where these varnishes are to be used, because the possibility of tearing in heavily working wooden parts, such as frame connections on superstructures or older glued connections, is very high.
These varnishes also attract very quickly, they can only be used at certain temperatures and humidity levels. Achieving a good result with a paintbrush is therefore rather difficult.
However, with spray painting, excellent and, above all, more permanent results can be achieved.
Products: Awlbrite plus,
Hempel’s Diamond Varnish;
SP 2000 Ultravar can also be used to top coat epoxy coatings.
The colored paints that we use for the outer skin, water pass, cabin roof and other items are also based on alkyd resin or polyurethane.
Pure oil varnishes are rare.
Due to their pigmentation, the colored lacquers are much more UV-resistant than their “clear colleagues”. Some outer skin only needs to be repainted every two or three years, not every year, as is essential with one-component clear coats.
The American PU products from AWLGrip are particularly durable. These 2-component lacquers keep their gloss and color fastness for several years.
The PU lacquers include e.g. International Toplac or Brightside.
The alkyd resin lacquers include e.g. Sikkens Highgloss or Hempels
The PU lacquers are also a bit more sensitive to cold during processing.
The alkyd resin lacquers can be outwitted with a dash of Owatrol oil at cold temperatures and can be easily spread with good flow.
Conservation of raw wooden hulls
If an underwater hull is to be completely removed and rebuilt, the hull must be examined for defects before conservation. Rotten wood should be replaced, corroded metal parts replaced if possible.
It makes sense to impregnate the hull with a fungicide such as Intertox or Imp and protect it from rot.
This is followed by painting with a chlorinated rubber primer such as B. Owatropal, Hempels Barrier Primer or International Primocon.
Here, too, there are other systems, many yacht owners swear by the preservation with linseed oil.
Sometimes the decision here is more of a philosophical one.
If you want to smooth the hull by filling, you should do it after the first layer of primer, because the bumps are now easier to see. However, it would be better to sand the hull so smooth that you can do without spatulas.
You should never close fine plank seams with a 2-component spatula, because it becomes too hard.
A soft lacquer spatula is used here, which dries slowly but never becomes very hard.
Window putty, made “slim” with linseed oil, is also right here.
After filling, three more layers of primer follow, followed by the anti-fouling paint.
Preservation of metal parts
Here we mainly think of the tiresome ballast keel made of cast iron and the iron associations in the ship such as B. Floor walls or steel frames in composite constructions.
It would be ideal to dismantle the parts, blast them and galvanize them. Unfortunately, the effort is usually too great or it is simply not possible to get iron parts out of the ship without causing major damage.
The possibilities of preventing the progressive corrosion of iron parts are limited; it can only be reduced.
Before the preservation, the metal parts should be derusted as much as possible. This can be done with the simple steel brush or, if possible, with a braid brush on the Flex.
The market offers various products for preservation, good results are achieved with ZN 95 or Epi-Resist, an epoxy product from Yacht-Line.
Preservation of the bilge
Basically, the following applies here: Without ventilation of the bilge, any conservation is pointless!
In a permanently wet or humid climate, even the best preservation cannot withstand a fungal attack with subsequent rot formation. Often the condition of a wooden boat can be guessed at with the nose.
With normally planked classic yachts, whose wooden hulls in the bilge area always have a moisture content of more than 15%, it would not make sense to paint the wood with closed pores.
Here we prefer oils such as Benaroil, Imp, Owatrol (attention: vapors!) Or pure linseed oil. The moisture can escape here, the trunk can breathe.
Molded hulls can also be painted with modern paints in the bilge area.
Honing and sanding wooden hulls
Especially fresh owners of classic yachts feel the irresistible urge to pull off the underwater hull or the surface hull in order to see the condition of the wooden planks in their true beauty. Often there is the desire to apply a clear coat to a colored hull, which often leads to disappointment because the wood of the surface hull is not as beautiful as expected or many black spots on the riveted or screwed connections impair the overall appearance.
Nevertheless, in many cases it makes sense to remove over-aged layers of paint and tackle the tedious and exhausting subject.
In the meantime, professional companies also offer the gentle blasting of wooden hulls. The company Get Off (www.getoff.de) should be mentioned here, which has already blasted some wooden hulls.
If the financial or spatial possibilities do not allow professional use, you have to do it yourself. It would be extremely beneficial to win a few strong and resilient friends or crew members for this leisure activity. It is easy to lose heart when faced with this task alone.
There are really only two methods for the procedure: scraping or stripping, which usually causes a terrible smear.
In addition, most paint strippers only work properly at temperatures above 15 degrees C. So this method is out of the question, sanding doesn’t work either, because the antifouling hopelessly clogs even the best sanding paper.
The Sandvik scrapers with hardened, double-sided blades 50 mm wide are best suited for scraping underwater vessels, because extremely hard layers of primer can lie under the antifouling. You should rather refrain from using a heat gun for the underwater hull, because particularly toxic gases are produced when the paint is burned. In any case, including when scraping and sanding, a good protective mask (e.g. from the 3M) must be used for this work.
Before the final removal of all paint layers, the position of the water pass should be secured with small nail points or punctures with a pointed drill at a distance of approx. 0.5 to 1 meter.
Are the thickest layers of paint removed by scratching and only
If only a few thin residues remain on the outer skin, you can start sanding.
In the underwater area, machine assistance can be used safely. Orbit sanders from Festool or Fein with external extractors are best suited here.
The do-it-yourself machines with integrated extractors tend to distribute 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, one should make an effort to achieve a nice surface without holes and bumps.
The layers of paint on the freeboard can be easily removed with the help of a heat gun. The “yacht scraper” from Toplicht is best suited as a scratch. You can find these scratches in every paint shop, but here the blades are usually too thin. They flutter at work and leave ugly grooves in the wood.
Grinding the freeboard, be it natural or colored, is something for experts. The brighter the surface is when painting, the more clearly the unevenness becomes visible.
The surface can easily be sanded with the eccentric sander to remove the last layers of paint.
The fine sanding should definitely be done by hand with a sanding board, preferably first in a diagonal direction and then in a lengthwise direction, first with coarse sandpaper (approx. 80 grit), then gradually becoming finer up to 120 or 150 grit 240.
Sandpaper shouldn’t be in a hardware store, but in a paint shop
be procured, there are great differences in quality. There are good products from Sia, Mirka, Klingspor, Würth.
In the case of colored hulls, the aim should be to do without filler completely, slightly opened plank seams are filled with a soft varnish filler.
Painting of colored boat hulls
If you have decided on a color system, whether 1- or 2-component, you should definitely stick to this system from priming to final painting; this also applies to thinners!
The primer layers, about two to four depending on the absorbency of the wood, can be applied with a good foam roller. If the specified overcoating intervals are adhered to, no intermediate sanding is required. If you don’t want to do without a spatula, it should be done after the first primer.
After the primer, a fine intermediate sanding must be carried out, which can now be carried out with a machine with a very fine grain (320). The risk of grinding bumps into the surface is no longer so great.
You can now start with the first coat of paint, only one will usually not be enough.
The paintwork can also be applied with a foam roller and smoothed with a foam brush.
The course of the paint surface depends primarily on the product itself and the processing temperatures.
One-component paints can be made more run at low temperatures with a dash of Owatrol oil.
Two-component paints can also be thinned; the prescribed product must always be used here. 2-component lacquers should not be used below a processing temperature of 10 degrees C.
Painting of natural hulls
If a hull is to be stained before the first painting, it is advisable to moisten the wooden surface with a wet sponge. The softer pores now swell and stand up when they dry up, the surface is now rough again.
This effect would also have occurred after the stain had been applied; the first coating would now have been applied to a rough surface.
After soaking, the surface is sanded again very finely, then it can finally be painted, again with a foam roller and foam brush.
This is best done with two people.
The processing instructions of the paint manufacturer regarding thinning should be observed.
The first thinned layers of lacquer can be applied without intermediate sanding within the specified intervals, after which intermediate sanding should be carried out.
Many owners of classic yachts swear by a 400 wet sanding before the final painting. However, a 320 machine grind is sufficient.
Rubbing with a sanding pad is also sufficient if the surface is flawless.
The most important and the most difficult thing before a top coat is complete dedusting in order to achieve a good finish.
The surfaces should be vacuumed with a good vacuum cleaner with a brush and covered with a clean cloth with e.g. Benzine or soft surface cleaner. Then the area is treated again with a dust cloth.
The area around the ship should also be reasonably clean, drafts must be avoided at all costs, and painting should not be carried out on stormy days.
In spite of following these rules, the professional yacht painter is often in despair because the painted surfaces, especially those lying flat, keep showing dust particles.
To reassure you, it should be said that you can’t see anything of it in the water.
A one-component coating should have at least 8 to 10 coats. In the case of intermediate sanding, it is important to ensure that curves are not sanded too hard, in order not to accidentally remove the layer thickness.
The annual renewal of natural paintwork
One-component natural paintwork must be renewed annually to stabilize the UV protection. There have been quite a few nasty surprises when the paintwork has been suspended for a year.
As a rule, after cleaning with clear water, it is sufficient to simply sand the surfaces with fine paper (320).
However, if there are spots down to the raw wood or moisture penetration, this area should be sanded down to the wood and built up with varnish in approx. 5 to 8 layers.
It is advisable to work on these areas before sanding through all surfaces because they are difficult to identify afterwards.
If you want to sand through the entire surface beforehand, the areas must be marked.
Masking of water pass, superstructures, etc.
Before tapes are stuck to freshly painted surfaces in order to separate surfaces for painting from each other, you should be sure that the paint is sufficiently hardened. Otherwise it can happen that the fresh paint is peeled off when the adhesive tape is torn off.
In the open air, in particular, make sure that the tapes do not remain on the surfaces for too long. You could have difficulty removing them, even with special tape removers.
The standard Tesa tape is used very often, it is very thick and adheres far too well, which is usually not necessary.
There are now a lot of new products that are thinner, much more elastic and easier to remove. However, they are also significantly more expensive. One of these products is called SLIM.