The same every spring: The garden furniture, the fence, the window – everyone thirsts for a new coat of paint. And the question keeps coming up, which means is actually better – varnish or glaze. We clarify!
The discussion is as old as wood protection itself. For my wooden structures in the garden and on the house, do I prefer to use the open-pore glaze or rather the opaque lacquer? The answer, as is so often the case, is the widely appreciated one, solomonic: "It depends on!“ That’s how the paints are in terms of the environment, for example- and health compatibility have been further developed in recent years, that glazes are no longer more environmentally friendly per se. On the other hand, the thick-film glazes, for example, have been refined in this way, that they are hardly inferior to lacquers in terms of opacity.
WHY WOOD PROTECTION?
The world is cruel! And so it is not surprising, that also the fences we built, Gates and Pavilions have natural enemies. Above all, sun and water damage the wood so mercilessly, that, unprotected, it would have a life expectancy of only a few years. The water is more of an indirect danger, because by itself it does not harm the wood. Over time, water washes out some of the wood's constituents, what the, statically irrelevant, graying of the wood surface. Otherwise, water and moisture only pave the way for the much more dangerous fungi and insects, that decompose the wood.
The second culprit, the sun, is completely different: Their well-known and feared UV rays destroy the building material lignin, which gives the wood its strength and stability. bark and bark, which protect the trees in the wild from the destructive rays, are naturally omitted with built-in wood. Wood protection outdoors is therefore necessary, if you want your building to last a long time.
Good wood protection prevents, that water penetrates permanently and deeply into the wood, but it is open to the natural moisture balance between the wood and the ambient air. Good wood protection continues to prevent, that the UV rays penetrate to the inside of the wood, but it does not hide the grain and thus the beauty of the wood.
Varnish and glaze can both fulfill these tasks, albeit in very different ways and with different pros and cons.
PREPARATIONS
The preparation of the wood before painting is almost the same for varnish and glaze. Both require careful removal of all loose parts and chips, either putty over damaged wood (with opaque paint or thick layer glaze) or replace it entirely. Important: The wood must be absolutely dry for painting.
As a rule, you will not be able to remove old layers of glaze completely, even with the coarsest sanding, therefore only sand glazed surfaces with 80 grade sandpaper, until no more loose residue comes off. The coloring is mostly preserved. That's why you can at a second- or third-party treatment with a glaze, always use the same or a darker color, never a brighter one. The result would otherwise be a piebald wood surface.
With paint, you should always remove as much of the old paint as possible. When looping isn't enough, take a heat gun, which you aim at the paint surface for so long, until it starts to bubble and can be easily removed with a spatula.
Leave very tight coats of paint on the wood and only sand them roughly, to improve the adhesion of the subsequent paint. Important after each use of hot air: The wood surfaces must be of medium grain (100is- up to 120 grit) be sanded clean, the edges are easily broken.