22 PAINT TECHNOLOGY AND TESTS 



This oil was distributed into a number of 8-oz. oil sample 

 bottles, and to a series of these bottles was added varying quan- 

 tities of a very concentrated drier made by boiling oil to 400 

 degrees Fahrenheit in an open kettle, with the subsequent addi- 

 tion of lead oxide. The amount of drier added to each bottle 

 varied according to the percentage desired; being calculated 

 on the lead content of the drier, which was very accurately 

 determined by analysis. 



There was secured in this manner a series of oils containing 

 varying amounts of lead oxide, and from this lot was selected 

 a certain number of samples which would be representative 

 and typical of paint vehicles now found in the market. 



Another series of tests were made by combining with a large 

 number of samples of pure linseed oil as used above, various 

 percentages of a manganese drier made by boiling oil at 400 F. 

 and incorporating therewith manganese dioxide. 



Still another series of tests were made upon a number of 

 oils into which were incorporated various small quantities of 

 lead oxide and manganese oxide together, using the standard 

 driers made in the above manner, all of which were carefully 

 analyzed to determine their contents. 



In view of the errors in manipulation that could occur where 

 so many tests were made, it was not deemed advisable, in carry- 

 ing out the tests, to use glass plates on which only a minute 

 quantity of oil could be maintained. A much better solution 

 of the difficulty presented itself in using a series of small, round, 

 crimped-edge tin plates, about three inches in diameter, such 

 as are used for lids of friction-top cans. 



With paints it is impossible to secure films as thin as those 

 presented by layers of oil on glass, nor would it be desirable 

 to secure films of this same relative thickness. For this reason 

 an endeavor was made to conduct the following tests with films 

 of the same relative thickness as that possessed by the average 

 coating of paint. The drying of the films did not take place 

 in the same short period, nor in the same ratio, as with the thin 

 layer that is secured by flowing oil upon glass. The results, 

 however, are more practical, and of greater value to the manu- 

 facturer. 



The cans were carefully numbered in consecutive order, 

 corresponding to the numbers on the various samples of oil. 



