The writer has recently made a careful inspection of the panels painted with single pigment paints, and has made the following brief summary of the characteristic appearance of each.
Panel No. 1—Dutch Process White Lead. The excessive chalking which took place began to disappear at the end of a year, being washed away by the rains and carried away by the winds, so that there was left upon the surface but a thin coating of pigment, insufficient to give good protection. Slight corrosion was apparent beneath the film.
Panel No. 2—Quick Process White Lead. In the same condition as Panel No. 1.
Panel No. 3—Zinc Oxide. Panel covered with thin lateral streaks of rust, due to the admittance of moisture in cracks caused by brittleness of film. Result doubtless due to insufficient amount of oil used with pigment. Removal of film shows steel very bright except where cracks have formed.
Panel No. 4—Sublimed White Lead. Although sublimed white lead chalked very heavily, the chalked pigment seemed to 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 surfaces. 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 apparent. 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.