PAINT TECHNOLOGY 



CHAPTER I 

 PAINT OILS AND THINNERS 



Constants and Characteristics of Oils and Their Effect upon 

 Drying. An attempt has been made to give in this chapter a brief 

 summary of the most important characteristics of those oils 

 finding application in the paint and varnish industry. For 

 methods of oil analysis, the reader is referred to standard works 

 on this subject; the analytical constants herein being given only 

 for comparative purposes. 



It is well known that one of the most desirable features of a 

 paint oil is the ability to set up in a short period to a hard 

 surface that will not take dust. This drying property is depend- 

 ent upon the chemical nature of the oil. If it is an unsaturated 

 compound, like linseed oil, rapid absorption of oxygen will cause 

 the film to dry rapidly and become hard. If the oil be of a 

 fully satisfied nature, like mineral oil, oxygen cannot be taken 

 up to any great extent and drying will not take place. The 

 various animal and vegetable oils differ in their power of oxygen 

 absorption to a lesser or greater extent. This difference is referred 

 to by the chemist in terms of the iodine value. The iodine value 

 of linseed oil is approximately 190, meaning that one gram of 

 the oil will take up 190 centigrams of iodine. Oils with high 

 iodine values have good drying powers, while those with low 

 iodine values are, as a rule, very slow drying in nature. 



For a description of the working and drying properties of various 

 oils used in paints, see Chapter XIV. The oxygen absorption of 

 various oils and mixtures is shown in Chapter II. 



Linseed Oil. The seed of the flax plant which is extensively 

 grown in North Dakota, Argentine Republic and Russia, con- 

 tains approximately 36% of oil which may be obtained by grind- 

 ing, heating, and expression. Ripe native seed generally produces 



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