Boiled linseed oil – FineWoodworking

Linseed oil—pressed from the seeds of the flax plant—has been utilized by woodworkers and artists for hundreds of years. It’s versatile and cheap. In its uncooked kind, combined with pigment, it makes artist’s oil paint. When heated, it makes a superb penetrating wooden end.

Linseed oil is called a drying oil as a result of it reacts with oxygen and finally types a tough movie. Chemists name the method polymerization. (Tung oil, from the seeds of the tung tree, is the opposite extensively used drying oil.) Canola oil and olive oil are two kinds of nondrying oil. They by no means solidify to kind a movie, which is why they’re higher for cooking than cabinetmaking. Between these extremes are semi-drying oils, akin to soybean and safflower, that are used to make varnish.

There are a number of kinds of linseed oil. The one which woodworkers most frequently use is boiled linseed oil, or BLO. It makes a wonderful, sturdy end that darkens because it ages. Tung oil is much more sturdy and darkens the wooden much less.

BLO can be one of many elements within the combination often called Danish oil, together with varnish and a solvent akin to turpentine or mineral spirits. The varnish permits Danish oil to kind a thicker movie than BLO alone. Waterlox is the same oil-varnish combination, created from each linseed oil and tung oil.

Despite its identify, BLO isn’t boiled, however it’s heated. Most manufacturers of BLO are combined with heavy-metallic driers, sometimes salts of cobalt and manganese. Those components pace BLO’s response with oxygen, permitting it to dry in a day or so. Raw linseed oil, with out the heating and the components, can take weeks to dry.

Like different oil finishes, BLO is insanely straightforward to use: Hand-sand the piece you’re ending to no less than 220-grit. Wipe on the oil with a cotton rag and wipe off the surplus. Wait a day, frivolously burnish the surfaces with a grey nonabrasive pad, and apply one other coat of oil. Repeat till you get the texture and sheen you need. Just don’t anticipate an oil end to construct like shellac or wipe-on poly. The oil penetrates the wooden as an alternative of sitting on high of it.

Oil finishes current the hazard of spontaneous combustion. Wadded-up oily rags will take in oxygen, beginning a chemical response that generates sufficient warmth to make the rags burst into flame. That’s a certainty with BLO, much less of a certainty with tung oil. Some sources preserve that tung oil isn’t more likely to burn as a result of it has a excessive flash level. But why danger a hearth? If you’re utilizing a end that incorporates BLO or tung oil, unfold the rags out on the bottom or dangle them on a rack till they’re dry.  Only then are you able to safely discard them.

There’s one different concern with BLO: meals security. Because most manufacturers of BLO  include heavy-metallic driers, they aren’t thought-about meals protected. So if you’d like an oil end on a butcher block or reducing board, or on a carved spoon or a turned serving bowl, select one thing apart from BLO. For instance, The Real Milk Paint Co. sells a pure tung oil that’s meals protected. Woodturner Mike Mahoney sells a warmth-handled walnut oil that dries shortly and is meals protected. Or, use a model of linseed oil that doesn’t include doubtlessly hazardous elements. These embody finishes from Tried & True and Odie’s Oil (a model favored by woodturners). The maker of Waterlox says the end is meals-protected when dry.

For extra data on oil finishes, try our Finishing Guide.