CHAPTER X 

 A LABORATORY STUDY OF TEST PANELS 



Panel Sections for Laboratory Test. In order to make a 

 laboratory study of the painted panels on the Atlantic City 

 and Pittsburg fences, it was thought advisable to remove small 

 sections from representative areas and transfer them to the 

 laboratory for such work. The fences were visited by the offi- 

 cial inspection committees soon after the first annual inspection, 

 and the panels were carefully looked over. Upon each was 

 marked out a representative portion, care being exercised to 

 select areas where previous inspections had not disturbed the 

 surface of the film in any manner. The inspectors then placed 

 the number of the panel upon the areas which had been marked 

 off, as well as their initials. The marked sections were sawed 

 out, wrapped in tissue paper, and then transferred to the labora- 

 tory where they were placed upon models of the respective fences 

 from which they had been removed. The illustration shows 

 the model test fences set up together. It is very apparent that 

 the Pittsburg panels are much the darker in color, due to the 

 soot, and in some cases lead sulphide formed upon their surfaces. 

 This difference was undoubtedly due to the atmospheric con- 

 ditions prevailing where the tests were made. One would be 

 led to suppose that a paint film exposed to an atmosphere such 

 as is found in Pittsburg would show deterioration more rapidly 

 than one exposed in Atlantic City. In all the tests and experi- 

 ments, however, the Atlantic City panels appeared broken down 

 to a much greater extent; though it is true that the Pittsburg 

 panels had darkened considerably and presented a rather mot- 

 tled appearance. The deposit of soot on the Pittsburg panel 

 seemed to act as a preservative coating for the film beneath, 

 and prevented marked disintegration. 



Chalking Test. Small strips of black felt, about one inch 

 square, were firmly attached to a block of wood, and by a clamp 

 having the same pressure in each case, the wood with its surface 



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