Linseed oil
Linseed oil, or simply linseed oil, is oil from the seeds of oil flax. Oil flax belongs to the same species as fiber flax, but differs from fiber flax in that the plants of oil flax are short and highly branched and those of fiber flax are long and poorly branched. The seeds of oil flax contain approximately 40% oil.
Linseed oil is made by pressing the seeds of oil flax. The remainder of the flax seeds are used as flax cakes for animal feed. A high seed yield is therefore important when growing flax for oil production.
Linseed oil must be stored in dark bottles, because the oil deteriorates in quality under the influence of (sun)light.
History
Until about 1930, linseed oil was extracted from flax seed in oil mills and with oil wringers and hand mills. There are several mills where oil is still minted. In the North and East of the Netherlands these are De Passiebloem in Zwolle, the Woldzigt in Roderwolde, De Wachter in Zuidlaren, the Oostendorper watermill in Haaksbergen, Pelmolen Ter Horst in Rijssen, Noordmolen in Ambt Delden and the Korenmolen in Eerbeek. De Bonte Hen, Het Pink and Dezoeker still produce oil in the Zaan region. In the south of the Netherlands, the Kilsdonkse Mill in Dinther, the Holten’s Mill in Deurne, the Collse Watermolen in Eindhoven and the Leumolen in Nunhem do this. In Belgium, linseed oil is also minted in the Laermolen, an undershot water mill, in Hoogstraten.
Human consumption
Linseed oil is not suitable for frying, as alpha-linolenic acid is highly unsaturated and therefore very sensitive to oxidation. Cold-pressed linseed oil (unheated) is used as a source of omega 3, 6 and 9 fatty acids, due to the high alpha-linolenic acid content. The content of omega 3, 6 and 9 fatty acids in linseed oil is the highest of all vegetable oils. Flax seed has been developed in which the alpha-linolenic acid content has been reduced through genetic technology.
Linseed oil from a natural oil flax variety has the following composition:
Linolenic acid >50%
Linoleic acid 10-20%
Oleic acid 10-20%
Stearic acid <10%
Palmitic acid about 5%
Eicosenoic acid <1%
Erucic acid <1%
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Industrial use
The product is marketed as raw linseed oil, cooked linseed oil (stand oil) or as flax oil (flax oil). Linseed oil is the most important component of linoleum. It is also used for making soap and synthetic resin. It is also used in bread.
Linseed oil is used to provide cast iron and steel pans with a protective layer, so that they are suitable for use in the kitchen. This is called burning a pan or baking tin.
Linseed oil is one of the earliest oils used for further processing in Europe. It is a component of various types of paint, including traditionally oil paint. It can also be used as a base for varnish lacquer. In addition, linseed oil is used for the preservation of unpainted wood and fishing nets. These uses are based on hardening (polymerizing) the oil. There are two types of flaxseed oil: raw and cooked. Raw linseed oil hardens less quickly than the cooked variety. “Cooked” linseed oil is usually not elevated in temperature but has metal salts (particularly cobalt) that catalyze polymerization.
Cloths contaminated with linseed oil can be a fire hazard due to polymerization. If rags or paper towels containing linseed oil are placed on a pile, an exothermic chemical reaction may occur, resulting in heat development. This is called ‘heating’ and can lead to fire. It is therefore recommended to hang rags and cloths containing linseed oil flat to allow the rags to dry.
Linseed oil is also found in cleaning products, including in liquid floor soap (mousse de lin).