WASHINGTON PAINT TESTS 209 



half pint to a gallon of paint; in the application of the second 

 coat there was added to each formula a like amount of an equal 

 mixture of turpentine and the oil formula under test. The 

 third coat was applied without the addition of thinners of any 

 kind. 



"It is well known that the time of drying and the condition of 

 the dried film of any oil or mixture of drying or semi-drying oils 

 will vary widely. It is for the purpose of causing oils to set up 

 to a hard film in a short time that metallic driers in the form of 

 salts of manganese and lead, soluble in oil, are added to a paint. 

 Some oils require a large amount of drier, while others require 

 only a very small amount. Those which require a large amount 

 are apt, upon exposure, to be burned up by the drier, resulting 

 in the formation of a powdered and disintegrated film. To add 

 various types of drier or even differing amounts of a drier to the 

 oils under test, seemed very unfair from every standpoint, and 

 it was therefore decided to eliminate the drier question entirely, 

 so as not to vitiate the results by bringing in a factor of this 

 nature. The plan of omitting driers proved successful in the 

 Atlantic City steel-panel paint tests, erected three years ago by 

 the writer under the supervision of Committee A-5 of this 

 Society. 



" The systematic methods which are necessary when making 

 paint tests were carefully followed. A standard weighed amount 

 of white pigment paste was placed in a clean paint cup and 

 thinned to the proper consistency with a weighed amount of the 

 oil under test. Proper reductions were made, as before stated. 

 Weighings of the paint, cup, and brush were made before and 

 after application to the panel, in order to determine the quantity 

 of paint used and the spreading power. A period of fifteen days 

 was allowed between the application of successive coats, in order 

 to give each formula sufficient time to dry thoroughly. Although 

 several of the formulas remained tacky for over a week, all dried 

 thoroughly in the time allotted. (Oils which when used alone 

 have slow drying properties, have been found to yield good firm 

 films when used with drying pigments such as lead and zinc.) 

 The backs and edges of each panel were painted with two coats 

 of the paint used on the face of the panel, so as to prevent the 

 admission of moisture. After erection, the panels were numbered 

 with aluminum figures pressed into the surface. Frequent 



