Some basic principles about oil:
Treatment of wooden ware with food-safe oils hinders liquids and food juices from being absorbed by the wood.
Both flax seed oil and linseed oil are the oil of flax seeds. Flax is a plant that was cultivated thousands of years ago and has been used for linen and oil since the beginning of civilization. The label “flax seed oil” is used for food-grade oil that is sold in health food stores as an edible product. Pure linseed oil may not have been produced with the idea of drinking it in mind, but it is still pure and safe for treating wooden ware for food contact. Conversely, hardware store “Boiled Linseed Oil” is not truly “boiled,” rather it has harmful ingredients added to speed drying time. Here is a simple break down of terminology as I understand it, but there are all sorts of labeling variations:
Cold pressed flax seed oil: Flax seeds are cold pressed and bottled in conditions that are so clean that the oil is fit for human consumption. Cold pressing simply means that the oil is removed from the seeds mechanically only. It is squeezed out.
Cold pressed linseed oil: The same thing as above, but not necessarily processed in a facility that meets the standards for human consumption. Still pure, cold pressed oil.
Refined linseed oil: Cold pressed oil that has been refined in some way, this could be through filtering, sun bleaching, heating (polymerizing), oxidizing with blown air, aging, or a combination of the above. There are many variations, and an entire article could be written about each of those processes, but I’m not qualified to do it. Looked at generally, these processes are intended to make the oil cure more completely and quickly, and/or be lighter in color.
Hardware store “Raw” Linseed Oil: I found the information on this after persistent pestering telephone calls to a production facility. They finally put me in touch with a very helpful employee who explained that after cold pressing, the seed mash still retains a significant amount of oil. This remaining oil is extracted through the addition of solvents such as hexane, resulting in a mixture of solvent and oil. The solvent is then evaporated off through the use of heat and careful processes, leaving behind 100% linseed oil. It is “raw” but not cold pressed.
Hardware store “Boiled” Linseed Oil: The name refers to the traditional practice of heating or polymerizing oil to make it dry faster, but this product is not truly boiled at all. Instead chemicals are added to the oil. Commonly these can be naptha, mineral spirits, or dipropylene glycol monomethyl. Cobalt and manganese are also usually added as drying agents. Even if you’re not in a hardware store, check and ask questions. For example, Allback’s Raw Organic Linseed Oil is pure, but Allback’s Boiled Organic Linseed Oil, while containing no solvents, does contain a manganese drying agent — a heavy metal. Although that information is provided if one asks, it should be made absolutely evident and clear in the product description.
Whether called flax seed oil or linseed oil, these are drying oils that penetrate the wood fibers and then polymerize (cure). Therefore, they provides lasting protection since they harden within the wood. Pure tung oil, walnut oil, and hemp oil are also pure drying oils that are good choices. Mineral oil, while harmless and providing some initial protection, is not a drying oil. It never cures and evaporates over time.
I have tried various suppliers of pure linseed oil . Some to try are Heritage Natural Finishes, Tried and True, and Viking. They refine and treat the oil through oxidation, blowing, and/or heat resulting in an oil that will polymerize faster. I bought a three gallon container of “Special Aged Linseed Oil” from Heritage Natural a while back, so that is what I’ve been using lately, and I like it a lot. Heritage Natural also has pure tung oil as does Real Milk Paint Co.
Regardless of source of the oil, heat speeds up and improves polymerization. Setting a piece in the hot sun, by the wood stove, or in a light bulb kiln will all work. I usually keep my kiln at about 120 degrees Fahrenheit and keep spoons and bowls in there for a day or two. For an occasional light refresh of a piece with oil, the heat is not necessary.
Here are some straightforward guidelines for continued care after a bowl has been initially treated:
If the bowl or spoon is just used for dry things or no things, it might need no treatment at all. Just dust it off with a dry rag.
Use with foods is fine, encouraged of course. Just avoid extremes like beet juice or a rotting peach soaking into the wood. We regularly use our spoons with hot tomato sauce, etc. with no staining or problems.
If it needs to be washed after stirring the pot, holding salad, etc., then just wash it with a wet rag at the sink (with a little soap if necessary), rinse, and dry it. Avoid soaking a bowl, and don’t put any of these things in the dishwasher.
In any case, if the wood starts looking a little dull or dry for your taste, you can reapply some oil or an oil/wax blend. See below for more wax blend options. Just wipe some on and rub off the excess. If you can, wait a day or two before using again.
Of course, something that gets used is bound to show signs of use. In my mind, this patina of use makes the object all the more beautiful. A spoon that is worn over the years from continually contacting the bottom of the pot has a character of its own. Ultimately it is up to the owner.
What about Wax?
If you’d like to maintain your woodenware with a little more luster, you might consider a beeswax/oil blend. These are food safe as opposed to most furniture waxes that contain harmful solvents and/or heavy metals like manganese. There are some varieties commercially available such as Heritage Naturals products, Real Milk Paint Co. products, Mahoney’s Oil Wax Finish, Tried and True Original, and Moses T.’s. Be careful and ask questions. For example Allback’s Linseed Oil Wax uses Allback Boiled Organic Linseed Oil which contains a manganese drier (a heavy metal).
You can also have some fun and make your own blend of oil and wax.
Making Your Own
It’s actually pretty easy to make your own oil/beeswax blend. If you’d like to try it, here’s one idea:
Put about four fluid ounces (1/2 cup) of flax seed oil in a glass jar along with about 1/2 ounce (by weight) of beeswax (about the size of a one inch cube). Put the jar into a pan of water on the stove and heat just until the wax has completely melted into the oil. Be careful with oil around flame. Stir to assure an even blending, set the jar aside and allow it to cool into a paste. Seal up the jar with a lid, and it is ready to go as you need it.
Just rub some into the wood, allow it to absorb for awhile (even overnight if you want), then buff off the excess with a paper towel.
You can also add just a touch of carnuba wax for a litte more toughness and luster.
Of course, you can make a bigger batch, or you can adjust the proportions of oil to wax to make a thicker or a thinner paste. To adjust the consistency , just add more oil or wax and remelt it.
David Fisher, Carving Explorations 