Larch wood is also a not entirely unproblematic type of wood when it comes to painting and glazing. You can find out why this is so and which special properties you always have to take into account when painting larch wood.
Difficult properties of larch wood
Larch wood causes two problems when painting: on the one hand, it can be very resinous (which, however, does not apply equally to every piece of larch wood) and, on the other hand, larch wood naturally contains a lot of tannic acid. Neither of these makes opaque coatings easy.
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Protection needs of larch wood
Larch wood is naturally extremely weatherproof and durable. In many cases, it will not be necessary to paint it to protect it from the weather, and larch wood has a long service life, even if it is untreated. A varnish or a coat of paint as weather protection is usually not necessary for larch wood, even if it is used outdoors with high-quality wood.
Protection against graying
Over time, however, untreated larch wood acquires a certain patina. This silver-gray surface layer is not a sign of deteriorating wood quality, but a completely natural process. The wood thus protects itself from the effects of weather and UV radiation. To prevent graying, the wood must be given a coat of paint that protects it from UV radiation. Then this natural process is stopped.
However, there are differences - for example, the alpine larch, felled at the right time and from an optimal location, is usually much more durable than the lowland larch. These differences should also be taken into account. It is simply a question of wood quality.
Pay attention to when painting, glazing and staining
Oil varnishes and varnishes containing polyester can usually not be used on larch wood because of the resin content. Particularly resinous woods often cause problems with other types of lacquers and glazes, in these cases it is better to refrain from processing, as the result is usually not good. When pickling, too, one must ensure that a special pre-treatment with resin-soluble agents is carried out. The best thing to do is to seek advice on suitable products from the timber trade.
In order to prevent problems with tannic acid, one should either use suitable and designated products, or let the larch wood "weather" outdoors for a few weeks to six months before painting. The length of time for weathering depends mainly on whether you want to keep a light wood tone that has not been exposed to the weather, or whether the resulting patina then disappears under the paint color anyway.
With the selection of a suitable color, however, you can do without it. Above all, tannic acid causes problems with the drying properties of most varnishes if it is too high in the wood. This uneven drying can also lead to a less attractive color result.Tips & Tricks Only heartwood is weatherproof and durable! With any type of wood, no matter how weatherproof, this never applies to sapwood. Practically every type of wood must be adequately protected. This also applies to larch wood.