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Linseed oil, also known as flax seed oil, is a 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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If it is very fresh, refrigerated and unprocessed, linseed oil is suitable for human consumption, and is used as a nutritional supplement. It is rich in omega-3 fatty acids, especially alpha-linolenic acid, which appears to be beneficial for preventing heart disease, inflammatory bowel disease, arthritis and a variety of other health conditions. Regular flaxseed oil contains between 52 and 63 % alpha linolenic acid (C18:3 n-3). Plant breeders have developed flaxseed with high alpha linolenic acid content (70 %) and very low alpha linoleic acid content (< 3%). Flaxseed also contains a group of chemicals called lignans that may play a role in the prevention of cancer.
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).
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 not only 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, however a very fine finish may require months to obtain.
- Animal feeds
- Caulking compounds
- Brake linings
- Earthen floors
- Bicycle maintenance as a thread fixative, rust inhibitor and lubricant
- Foundry products
- Leather treatment
- Polishes, varnishes and oil paints
- Composition ornament for moulded decoration
- Animal care products
- Wood preservation
- Synthetic resins
- Industrial Lubricant
- Treatment for the raw willow wood used to make cricket bats. Linseed oil has a special cultural place in cricket-playing countries.
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.
Rags dampened with boiled linseed oil are a fire hazard, because they provide a large surface area for oxidation of the oil. The oxidation is an exothermic reaction which accelerates as the rags get hotter. Such rags should be washed, soaked with water or incinerated to avoid unexpected spontaneous combustion.
Per 1 Tbsp (14 g)
- "HiOmega Flaxseed Oil Data Sheet" (PDF). Polar Foods. Retrieved 2007-09-25. Data sheet for Polar Foods' flax seed oil product containing 70% omega-3.
- Thompson, Lilian U and Cunnane, Stephen C. eds (2003). Flaxseed in human nutrition. 2nd ed. AOCS Press. pp. 8–11. ISBN 1-893997-38-3.
- "Flaxseed Oil". University of Maryland Medical Center. April 2002. Retrieved 2006-11-12. Check date values in: