“On Panels 120 and 126, which represent formulas 6 and 9 respectively, the grays are in most excellent condition, and it will be found, by reference to formulas 6 and 9, that there is an absence of white lead in their composition. These formulas, however, contained a small percentage of umber and ochre. Formulas 5 and 16 contained over 20% White Lead and the gray of these formulas maintained their blue tone very well. These formulas were tinted solely with lampblack.
“An inspection of Panel 138, which represents Formula 15, showed good maintenance of color in the gray, and was in much better condition as regards permanence of color than the other grays containing white lead.
“A study of the yellow panels on the fence led to the unanimous conclusion that a liberal amount of Basic Carbonate-White Lead seemed to have a beneficial result in preserving the bright tone of the chrome yellow in tints so strong as those used on the fence. It was noted that Panel 108, which represents Formula 28, and in which zinc yellow was used, showed great permanence of tone and tint. Unfortunately this zinc chromate was added to a formula containing a large percentage of lithopone, and the destruction of the lithopone to a great extent affected the value of this test.
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| Whiteness of Sublimed White Lead | Darkness of Corroded White Lead |
| On Pittsburg Test Fence | |
“Maintenance of Para Reds. A study of the paranitraniline or azo reds painted over the various pigments as priming coats demonstrated that the reds on this fence are in better condition than the reds at Atlantic City. As is well known, para red is manufactured by precipitation in an acid solution and is best maintained under acid conditions. The acidity of the Pittsburg atmosphere, caused by the large amount of acid gases which are being poured into the air, day in and day out, and which are constantly condensing on the surface of structures, may account for the better preservation of these reds.
“It was noted that the para reds which were applied to panels prime coated with white lead seemed to be brightening in color and seemed to be gradually working over toward a lightening which may in the future show a pinkish tint.
“Report on Greens. The bronze green is in most excellent condition and shows an absence of the mildew appearance which was observed at Atlantic City.
“The chrome green is standing up exceedingly well, there being practically no change whatsoever in the color since it was exposed.
“Best Base for Blues. An inspection of the blues showed that those which gave the greatest permanence and the least amount of fading were applied in combination with either Sublimed White Lead (Basic Sulphate-White Lead), or zinc oxide, while those blues which were applied in combination with Basic Carbonate-White Lead showed marked failure and were completely bleached out, due, of course, to the alkaline nature of the corroded white lead; Prussian blues being transformed by alkalies to a white compound.