CHAPTER IV 

 PHYSICAL LABORATORY PAINT TESTS 



FOR the paint chemist who desires to familiarize himself with 

 the more recent analytical methods worked out in American 

 laboratories, reference may be had to treatises on the analysis 

 of paints, by Gardner and Schaeffer, 1 and Holley and Ladd. 2 

 Analytical methods are not included in this chapter, the writer's 

 desire being to treat the subject from the standpoint of the physi- 

 cal properties of painting materials. The work outlined herein 

 is of a nature that affords a wide field of research, and a brief 

 study will doubtless suggest similar work to the student of paint. 



Preparation of Paint Films. The study of paint films is one 

 that has become of vital importance, and is receiving at the 

 present time great attention. Among the many methods which 

 have been suggested and attempted for securing paint films, a 

 few already well known may be mentioned. 



By painting upon zinc and eating away the zinc with acid: 

 The objection to this method is very evident, namely, the action 

 of the acid upon the paint coating, which is likely to be very 

 severe. Another method has been to spread paraffin on a glass 

 plate, and painting upon this surface. When the paint is dried, 

 the paraffin is melted off and thus the film is obtained. This 

 method is open to objections, in that the paraffin surface is not 

 a comparable one upon which to paint, and also that the complete 

 removal of the paraffin is not assured. 



Another method consists in covering a piece of glass with tin 

 foil, painting out the film upon the foil, and after drying properly, 

 to remove the sheet of foil with its coating of paint and immerse 

 in a bath of mercury which, by amalgamation of the tin, leaves 

 the paint film. 



1 The Analysis of Paints and Painting Materials. McGraw-Hill Book 

 Co., New York, 1910. 



2 Mixed Paints, Color Pigments and Varnishes. John Wiley & Sons, 

 New York, 1908. 



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