SITE INDEX

NEW TECHNICAL SPECIFICATIONS

02/04:

LINSEED OIL

The quality of linseed oil for technical purposes (or for use as a drying oil) depends largely on its degree of unsaturation, as indicated by its iodine number. … With other factors equal, the colder the climate in which flaxseed is grown, the higher the iodine number of the oil. The tendency of flax (and other plants also) to produce oil of relatively low unsaturation has been attributed to the absence of sharp variations in the temperatures between the days and nights¹, but evidence has been accumulated² which points to the mean temperature during the period of seed growth as the determining factor. … It has been pointed out³ that a moisture deficiency during the growing season contributes to low iodine numbers in the oil.

¹ S.L. Ivanov, Allgem. Oel. Fett-Ztg., 29, 149-150 (1932)

² A.C. Dillman and T.H. Hopper, U.S. Dept. Agric. Tech. Bull. No 884, 1943

³ H.R. Sallans, Can. J. Res., F22, 146-156 (1944)

(source: Bailey’s Industrial Oil and Fat Products, Volume 1, 4^th edition, 1979)

HEAT AFFECTS FLAX QUALITY

The hot, dry conditions in some parts of the Canadian prairies during this past summer generally worked in favour of a good quality flax production. … However in some areas of Saskatchewan, where near drought conditions were present, other quality factors, in particular oil quality declined. In those areas, high daytime temperatures did not drop at night the way they usually do. (In Western Canada, cool summer nights normally work in favour of a high quality oil in flaxseed.) Instead, this year, some growing areas experienced constant day and night heat. Thus, oil quality, which is measured in iodine values (IV’s) dropped to about 183 units in Saskatchewan from the ten-year mean of 194 units. … Iodine value in flaxseed is one indicator of oil quality. For this reason, IV is one of the oil quality parameters to which industrial users of flax pay attention. … Because of their usefulness to manufacturers of industrial goods, IV’s are measured by the Canadian Grain Commission in all flax which is exported and, annually, in samples received from producers after harvest. …

(source: Flax Focus, 2003 – volume 16, number 2)

HOW DOES THIS EFFECT LINSEED STANDOIL

Linseed standoils are produced by the controlled polymerisation of a refined linseedoil at high temperatures. At these high temperatures, the non-conjugated double bonds, widely present in linseedoil, start to isomerise into their conjugated form. Once conjugated, they can react with a nearby double bond (Diells-Alder) to form a dimere. These dimeres can further react to trimeres and sometimes even higher.

The time needed to achieve a certain viscosity is closely related to the reaction temperature and the amount of double bonds (iodine value, IV) present in the oil. Since linseedoil from the last crop 2003 is significantly lower in IV, reaction times needed to achieve a certain viscosity have increased likewise.

The acid value (AV) of a linseed standoil is closely related to the reaction temperature and the reaction time. Since reaction times to achieve a certain viscosity have increased substantially since working with linseedoil from the last crop 2003, the AV has increased compared to that of a standoil of a corresponding viscosity from older crops.

Increasing the reaction temperature would shorten the reaction time, but may still increase the AV since more FFA would be generated. Moreover, increasing the reaction temperature is not an option, for obvious safety consideration.

Because of this, we have been forced to issue new technical datasheets for our range of standoils, with consequently higher AV’s.