I will grab the occasion to share some knowledge about creating furniture surfaces using linseed oil. linseed oil is a natural product with many uses. One of them is to use it to create finishings of wooden surfaces.
I would not use it for all and every use case, e.g. I would object using it for macropore wood like oak. Oak also contains tannic acid, so I guess it could lead to discolouring.
However, fine pored timber like fir, beech, cherry, or maple, will benefit from such a treatment. The result is a silk-mat finish, which resists most of the common conditions and allows for vapor diffusion. I even use it for counter and table tops. I have a table with a 50mm plate which has seen many parties. Of course it has some scratches. But it forgave all cigarettes, beer bottles and red wine remains so far. A lacquer surely had given up already.
Unfortunately there are many joiners who do not know how to do it right. They treat linseed oil just like a lacquer and afterwards complain that it just sucks.
There are two key points you need to respect.
Firstly, the oil does not build a thick film (compared to the lacquer). Instead, it penetrates the surface of the wood. Thus it is not that much of a coating, but more a “hardening” of the material itself. Unlike oil, a lacquer is coating the wood, levelling smaller scratches and roughnesses of the material. As a consequence, it is absolutely essential to sand the wood with a grit size of at least P150, better P180, when you intend to use oil. In the past, I was often surprised that joiners had only P120 sanding paper on stock.
Secondly, a lacquer gets applied with an airbrush. It almost does not make a difference how much material gets applied. The lacquer dries and gives you a nice coating. If you try the same with linseed oil, you will get a finish which will not dry for years, giving you a sticky surface which renders your workpiece almost useless (this is at least true for chairs ;-) .
So here’s a small step-by-step receipt which hopefully helps you to get the best out of an oiled piece of wood:
- Sand your workpiece carefully. Use a sanding paper of at least P150 grit size, better P180. Do not sand across the wood grain, and do not use rotary sanding machines. Better use band grinders. The oil will otherwise show any scratches which damaged the grains.
- Mix linseed oil with turpentine in a ratio of 1:1. Apply the mixture to the workpiece with a brush. Wait for about half an hour. Repeat the procedure until the oil stops sinking into the wood. This process depends on the actual wood used. Beech, for example, is known to be very greedy.
- After that, use a lint-free cloth to remove the rest of the material from the surface. Only a wee small film may remain. Yes, that’s true: most of the material gets wasted. The method is not efficient when it comes to the rate of yield.
- Take care about the cloth, as the oil in it made it pyrophoric; dry it outside or burn it in the fireplace.
- Wait the oil to be dried. The amount of time needed heavily depends on some factors. The process is a polymerization. It needs light and oxygen. Summer weather and temperature is a plus, air humidity a minus. Under good conditions the oil will dry in a couple of hours, but it also can last several days.
- After the oil is dry, use a fine-grained sanding paper of a grit size of at least P180, better P220. Gently sand the “primer”, without applying much pressure. If the sanding paper gets stuck quite often, the primer is not dry enough yet. Finally, remove the dust.
- Now repeate the steps mentioned above. Apply the oil mixture, wait a couple of minutes, then remove the remaining oil with a cloth. Remember that it is crucial that you do not leave a thick film. Let the oil dry again. Repeat the steps of sanding and oiling until you are pleased. For basic protection (e.g. carcase parts of a unit), one primer and one finish may be enough. For better results, you may want to repeat more often.
- Some use wax as the final finishing. The wax is anti-static, so the furniture will suck less dust. But I would avoid the wax for sitting furniture like benches and chairs or tables.
- Ensure to put all tools and cloths into hermetically sealed boxes or burn them in a chimney. Otherwise you may be surprised of the wonders of chemistry, especially the oxidation, an exothermal reaction.
Linseed oil is an amazing natural product with many uses. I hope this short tutorial helps you to get a positive experience with oiled wooden surfaces and you enjoy them as I do.