228 PAINT TECHNOLOGY AND TESTS 



tural steel paints afford information of some import, there seems 

 to be a general opinion that the best method to follow, if informa- 

 tion of a reliable character is to be obtained, is to make actual 

 field exposure tests upon large surfaces. The results of the above 

 described water-pigment tests suggested the erection of a series 

 of steel panels on which to test out the same pigments under 

 practical service conditions. The Paint Manufacturers' Asso- 

 ciation of the United States erected and painted the panels, the 

 work being under the constant supervision of the writer, and 

 the inspection of the work under Committee U of the American 

 Society for Testing Materials. A brief resume of the work 1 is 

 herewith presented. 



Pickling and Preparation of Plates. The three types of 

 metal 2 selected for the test were rolled to billets, the middle of 

 which were selected, and worked up into plates 24 inches wide, 

 36 inches high, and f inch in diameter approximately 11 

 gauge. A number of plates of each of the metals selected, in all 

 450, were pickled in 10% sulphuric acid, kept at 180 to 200 de- 

 grees Fahrenheit, in order to remove the mill-scale. The plates 

 were then washed in water, and later in 10% solution of caustic 

 soda. Finally the plates were again washed in water and wiped 

 dry. They were then packed in boxes containing dry lime, in 

 order to prevent superficial corrosion. By this method the plates 

 were secured in perfect condition, the surfaces being smooth and 

 free from scale. Upon these pickled plates paints were applied 

 with a definite spreading rate of 900 square feet per gallon. The 

 unpickled plates, coated with mill-scale, were painted with the 

 same paints, but without adopting any special spreading rate, 

 thus following more closely the ordinary method of painting 

 structural steel. A few extra plates of special Bessemer steel 

 and Swedish charcoal iron were also included in the test, some 

 of which were painted, while others were exposed without any 

 protective coating. Plates of the three types of metal already 

 mentioned were also exposed unpainted, both in the black and 

 pickled condition. 



Fence Erection and Preparation for Work. The fences which 

 were erected for the holding of the plates were constructed of 



1 Page 181, "Corrosion and Preservation of Iron and Steel" Cushman 

 and Gardner McGraw-Hill Book Co., New York City. 



2 Bessemer Steel, Open Hearth Steel, and Pure Iron. 



