PAINT OILS AND TIIINNERS 



17 



as the last distillate in the refining of petroleum. These oils 

 when mixed with drying oils and strong driers find application 

 in the manufacture of some freight-car, barn, and other paints 

 which sell at a low price. A small percentage of mineral oil is 

 said to be valuable in structural steel paints, acting as a preventa- 

 tive of hard drying and thus keeping the film soft and elastic. 

 Streaking and sweating is apt to ensue if any great quantity is 

 used. Mineral oils have a characteristic bloom, showing a greenish 

 fluorescence when examined by transmitted light. This bloom 

 is due to the presence of some strongly fluorescent material which 



View of Stills Where Petroleum Paint Thinners 

 are Manufactured (Waverly) 



is shown up with intensity when mineral oils are exposed to ultra- 

 violet rays such as emanate from an enclosed arc light. Outer- 

 bridge 1 first proposed this test for mineral oils, and he has worked 

 out a " fluorescent scale," by which very small percentages of 

 hydrocarbon oils may be detected in other oils. Several types of 

 so-called debloomed oil have been placed upon the market, and 

 although such oils appear under ordinary light conditions to be 

 free from bloom, they fluoresce quite strongly when given the 

 Outerbridge test. 



Alexander E. Outerbridge, Jr.: "A Novel Method of Detecting Mineral 

 Oil and Resin Oil in Other Oils." Proc. 14th Annual Meet., Amer. Soc. for 

 Testing Mater., Atlantic City, N.J., June 28, 1911. 



