208 



PAINT TECHNOLOGY AND TESTS 



a resting place upon which they were finally secured with sher- 

 ardized screws. 



" Before erecting the panels, they were carefully painted in a 

 paint laboratory especially fitted out for the tests. The work 

 was done during the months of April and May, the temperature 

 averaging from 60 degrees to 90 degrees Fahrenheit. This 

 precaution was taken in order that the paint in each case might 

 become thoroughly dry and hard before exposure, so that there 

 would be no accumulation of dust or effect from exposure during 

 the drying period. The actual painting of each panel was done 

 personally by Mr. Charles Macnichol, master painter, of Wash- 

 ington, D. C., who has had a wide experience in the practical 

 application and testing of paints. 



View of Panels on Washington Test Fence 



" The viscous nature of several of the oils tested precluded 

 the possibility of grinding each oil formula with the white pigment 

 base selected; great heating of the paint mills and a paste of 

 insufficient fineness was the result of an early attempt at this 

 method. It was decided, therefore, to grind the standard pig- 

 ment formula to a thick paste in the minimum amount of raw 

 linseed oil. Subsequently a weighed amount of the white pig- 

 ment base was thinned with the oil formula to be tested, to a 

 standard viscosity, judged by the experienced master painter 

 in charge of the practical application of the formulas as sufficiently 

 heavy for third-coat work. When making the reductions with 

 oil mixtures, an allowance was made for the amount of linseed 

 oil already contained in the ground white pigment base. 



" During the application of the first coat an equal amount of 

 turpentine was added to each formula, in the proportion of one- 



