STRUCTURAL PAINT TESTS 237 



be tenacious and adhered to the plate, presenting an excellent 

 surface with absence of rust. Film of good color and quite 

 elastic. 



Panel No. 5 Sublimed Blue Lead. In same condition as 

 Panel No. 4, but color has slightly faded. 



Panel No. 6 Lithopones. Lithopone was early destroyed, 

 as is usual with this pigment when used alone on exterior sur- 

 faces. It became rough and discolored, presenting a very 

 blotchy appearance and disclosed the formation of rust working 

 through the film. 



Panel No. 7 Zinc Lead White. In general good condition 

 with the exception of the color, which is slightly dark. Medium 

 chalking was apparent but only very slight corrosion appeared. 



Panel No. 9 Orange Mineral. In excellent condition, 

 showing a good firm surface with no checking or corrosion appar- 

 ent. Shortly after exposure the film became covered with a 

 white coating of carbonate of lead, which indicates action of the 

 red lead with the carbonic acid of the atmosphere. Removal of 

 this white coating with water discloses the brilliant color of the 

 unaffected portion of the red lead. 



Panel No. 10 Red Lead. In same condition as Panel No. 9. 



Panel No. 12 Bright Red Iron Oxide. In general good con- 

 dition. Film intact and unfading in color. 



Panel No. 14 Venetian Red. Similar to Panel No. 12, but 

 slight corrosion apparent beneath, in localized spots, and film 

 showing slight wart-like formations. 



Panel No. 15 Prince's Metallic Brown. Similar to Panel 

 No. 14. 



Panel No. 16 Natural Graphite. Deeply pitted in spots, 

 showing bulbous eruptions, indicating the stimulative nature of 

 this pigment. 



Panel No. 17 Artificial Graphite. In same condition as 

 Panel No. 16. 



Panel No. 19 Lampblack and Barytes. Although the film 

 seems to be intact, there are apparent abrasions of the surface 

 showing stimulative corrosion effects of a pronounced nature. 



Panel No. 21 Carbon Black and Barytes. In same con- 

 dition as Panel No. 19. 



The longevity of lampblack and carbon black paint films when 

 applied to wood has been attributed to the slow drying nature 



