CHAPTER VIII 

 RESULTS OF ATLANTIC CITY TESTS 



Results on Various Woods. On the Atlantic City Fence all 

 the tests made on yellow pine and cypress were found to be in 

 an unsatisfactory condition for a report, for in every case the 

 sap and small knots contained in such wood had a very bad effect 

 upon the paint, causing peeling and scaling. The white pine 

 panels were in very much better condition, and it was therefore 

 decided to make the inspection entirely from the white pine 

 panels and in the future to remove the yellow pine and the 

 cypress panels from the fence and from the test. The Com- 

 mittee advised that all future tests be made on white pine, as 

 it is obviously unfair to use anything but the highest grade wood 

 for a paint test in which the desire is to determine the com- 

 parative wearing value of pigments. 



Paints Containing Lithopone. One of the most striking ex- 

 hibitions of paint disintegration in the whole test was the failure 

 of nearly all the lithopone formulas tested. At the time these 

 formulas were suggested for the test, various European technical 

 journals had advocated the use of lithopone in large percentage 

 for paints to be used on exterior surfaces. Good results had 

 been obtained in the northwestern section of Europe, with this 

 pigment in certain mixtures, and the object of these lithopone 

 tests at Atlantic City and Pittsburg was to determine whether 

 satisfactory paints could be made of this pigment for exposure 

 in this country. Failure of the tests, however, in nearly every 

 case except where zinc oxide and whiting were mixed with the 

 lithopone, indicated that pigments such as zinc and whiting are 

 necessary in order to prevent the decomposition of lithopone 

 pigment paints. The decay of lithopone paints after they are 

 applied seems to start with rapid oxidation of the linseed oil, 

 and this oxidation seems to continue in a progressive and even 

 accelerated way; after six months' exposure the surface of the 



NOTE. Recent tests have shown that Cypress may be successfully painted when the 

 priming coat of paint is thinned with Benzol (Solvent Naphtha) . 



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