Linseed oil
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Linseed oil, also known as flax seed oil or simply flax oil, is a clear to yellowish drying oil derived from the dried ripe seeds of the flax plant (Linum usitatissimum, Linaceae). It is obtained by pressing, followed by an optional stage of solvent extraction. Cold-pressed oil obtained without solvent extraction is marketed as flaxseed oil.
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[edit] Uses
[edit] Paint binder
Linseed oil is the most commonly used carrier in oil paint. It can also be used as a painting medium, making oil paints more fluid, transparent and glossy. It is available in varieties such as Cold Pressed, alkali refined, sun Bleached, sun thickened, and polymerised (stand oil).
[edit] Putty
Glazing putty, consisting of a paste of chalk powder and linseed oil, is a traditional sealant for glass windows that dries hard within a few weeks and can then be overpainted.
[edit] Wood finish
When used as a wood finish, linseed oil does not cover the surface as varnish does, but soaks into the (visible and microscopic) pores, leaving a shiny but not glossy surface that shows off the grain. Wood treated with linseed oil is resistant to denting and scratches are easily repaired, but the wood and oil surface is not as hard as a modern varnish, and it slowly absorbs moisture if allowed to stay wet. Soft wood benefits from the protection from denting but requires more applications and even more drying time than harder wood does, if the grain is to be completely filled. The oil penetrates deeply and fills the grain, because it dries slowly and shrinks little or not at all on hardening. Like other oil finishes Garden furniture treated with linseed oil may develop mildew. Linseed oil is not completely denatured, so it can encourage rather than discourage mildew growth. Oiled wood is yellowish and darkens with age.
It is a traditional finish for gun stocks, but a very fine finish may require months to obtain. Several coats of linseed oil is the traditional protective coating for the raw willow wood of cricket bats, and thus has a special cultural place in cricket-playing countries.
Fire departments treat the wood handles of hand tools that have metal implements (axes, plaster hooks etc.) on them with Linseed oil as it does not create static electricity, unlike synthetic wood finishes like varnishes.
Linseed oil is often used by billiards/pool cue-makers for the shaft portion of the cue.
[edit] Nutritional supplement
Food-grade flaxseed oil is cold-pressed, obtained without solvent extraction, and marketed as edible flaxseed oil. Fresh, refrigerated and unprocessed, linseed oil is used as a nutritional supplement. It contains high levels of omega-3 fatty acids, especially alpha-linolenic acid, which has been suggested to be beneficial for reducing inflammation leading to atherosclerosis,[1] preventing heart disease and arrhythmia,[2] and is required for normal infant development.[3] However recent well-controlled placebo studies suggest that regular consumption of flax seed oil may not reduce the risk of stroke, heart disease, or cancer any greater than placebo.[4] Regular flaxseed oil contains between 52 and 63 % alpha linolenic acid (C18:3 n-3). Plant breeders have developed flaxseed with high alpha linoleic acid content (70 %) and very low alpha linolenic acid content (< 3%).[5]
Although flax seeds themselves contain lignans, a class of phytoestrogens considered to have antioxidant and cancer preventing properties,[6][7][8] the extracted linseed oil does not contain the lignans found in flax seed,[6] and therefore does not have the same antioxidant properties. In fact, flax seed oil is easily oxidized, and rapidly becomes rancid with an unpleasant odor unless refrigerated. Even when kept under cool conditions it has a shelf life of only a few weeks.[9][10] Oil with an unpleasant or rancid odour should be discarded. Rancid oils contribute to the formation of free radicals and may be carcinogenic.[11][12][13] Oxidation of flax seed oil is major commercial concern, and antioxidants may be added to prevent rancidification.[14]
[edit] Nutrient content
| Typical Fatty Acid Content[15] | % |
|---|---|
| Palmitic acid | 6.0 |
| Stearic acid | 2.5 |
| Arachidic acid | 0.5 |
| Oleic acid | 19.0 |
| Linoleic acid | 24.1 |
| Linolenic acid | 47.4 |
| Other | 0.5 |
Nutrition information from the Flax Council of Canada.[6]
Per 1 Tbsp (14 g)
Flax seed oil contains no significant amounts of protein, carbohydrates, or fibre.
[edit] Additional uses
- Animal feeds
- Sealants
- Caulking compounds
- Linoleum
- Earthen floors
- Adobe
- Textiles
- Bicycle maintenance as a thread fixative, rust inhibitor and lubricant
- Leather treatment
- Polishes, varnishes and oil paints
- Composition ornament for moulded decoration
- Animal care products
- Wood preservation
- Industrial Lubricant
[edit] Boiled linseed oil
Boiled linseed oil is used as a paint binder or as a wood finish on its own. Heating the oil makes it polymerize and oxidize, effectively making it thicker and shortening the drying time. Today most products labeled as "boiled linseed oil" are a combination of raw linseed oil, petroleum-based solvent and metallic dryers. The use of metallic dryers makes boiled linseed oil inedible. There are some products available that contain only heat-treated linseed oil, without exposure to oxygen. Heat treated linseed oil is thicker and dries very slowly. These are usually labeled as "polymerized" or "stand" oils, though some may still be labeled as boiled.
[edit] Spontaneous combustion
Rags dampened with boiled linseed oil are considered a fire hazard because they provide a large surface area for oxidation of the oil. The oxidation of linseed oil is an exothermic reaction which accelerates as the rags get hotter. If rate of heat accumulation exceeds the rate of dissipation, this reaction may eventually become sufficiently hot to cause spontaneous combustion of the rags. Such rags should be washed, soaked with water or incinerated to avoid this. Linseed oil soaked rags should never be stored in an enclosed container. An example of this occurred at the El Rey Theater-Golden West Saloon in February 2008, which was destroyed in a fire ignited by the spontaneous combustion of linseed oil soaked rags. [1] [2]
[edit] See also
[edit] References
- ^ Diane H. Morris. Flax Reduces Inflammation Leading to Atherosclerosis. New Flax Facts. Flax Council of Canada.
- ^ Diane H. Morris. ALA and Other Omega-3 Fats May Protect Against Arrhythmia. New Flax Facts. Flax Council of Canada.
- ^ Diane H. Morris. Omega-3 Fats Are Essential For Infants. New Flax Facts. Flax Council of Canada.
- ^ Nigel Hawkes. "The benefits of fish and linseed oils as elixir of life are another health myth", Times Online, March 24, 2006. Retrieved on 2008-01-24.
- ^ Thompson, Lilian U and Cunnane, Stephen C. eds (2003). Flaxseed in human nutrition. 2nd ed.. AOCS Press, 8-11. ISBN 1-893997-38-3.
- ^ a b c Flax - A Healthy Food. Flax Council of Canada. Retrieved on 2008-01-24.
- ^ Diane H. Morris. Flax - A Smart Choice. New Flax Facts. Flax Council of Canada.
- ^ Flaxseed Oil. University of Maryland Medical Center (April 2002). Retrieved on 2006-11-12.
- ^ Flax Seed Oil Capsules. Flax Seed Oil. Retrieved on 2008-01-24.]
- ^ Flax Seed Oil. Busy Women's Fitness. Retrieved on 2008-01-24.
- ^ Rebecca Wood (August/September 2002). Flax Seed. Sentient Times. Retrieved on 2008-01-24.
- ^ Get the Facts on Flax. Dr. Andrew Weil's Self Healing (September 2006). Retrieved on 2008-01-24.
- ^ Dr. Andrew Weil (May 31, 2005). Are Nuts a Healthy Nibble?. Retrieved on 2008-01-24.
- ^ D. Berab, D. Lahirib and A. Naga (June 2006). "Studies on a natural antioxidant for stabilization of edible oil and comparison with synthetic antioxidants". Journal of Food Engineering 74 (4): 542-545. doi:.
- ^ Linseed. Interactive European Network for Industrial Crops and their Applications (October 14, 2002). Retrieved on 2008-01-24.
[edit] External Links
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