Flax seed oil (called linseed oil when used as a drying oil). High in omega 3 and lignans, which can be used medicinally. Easily turns rancid.[48]
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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.
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).
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.
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.