Rearranged Panels on FenceFront of Fence showing Present Rearrangement of Panels
Front of Fence showing Present Rearrangement of Panels
“There are no pigments possessing greater hiding properties when first used than white leads, but the lack of hiding power on the white lead panels after two years’ exposure was caused by the chalking away of the lead. The superior hiding power of the composite paints was due to the action of the other pigments in these combination paints in preventing the lead from chalking away.
“The Committee finds that the addition of a reasonable percentage of zinc oxide to white lead increases its durability and retards its chalking, renders it whiter, and forms a surface that presents a much better repainting condition. The combinations of white lead and zinc oxide on the Atlantic City Test Fence were in general good condition throughout.
“Corroded white lead, sublimed white lead, zinc oxide, and zinc lead are the standard white opaque pigments. They were all tested on the Atlantic City Fence and it was found that to use any one alone results in inferior protection to the wood. Barium sulphate, silica, asbestine, china clay, and calcium carbonate are the standard crystalline pigments. In the past, the overloading of paints with these crystalline or inert pigments has been the cause of the prejudice that painters have had against their use. It has been established beyond controversy, however, that the use of these pigments, in moderate percentage, combined with any of the standard opaque white pigments, such as white leads, zinc oxide, etc., undoubtedly results in better service from every standpoint and forms the most satisfactory white paint for general outside use. Some of the most perfect painted surfaces on the fence were those made on the above basis as reference to the charted report will show.”
The First Annual Inspection of the Pittsburg Test Fence took place during May, 1909, a little over one year after the painted panels had been placed in position. The inspectors found that in Pittsburg a heavy deposit of soot had formed on the panels, and they considered it therefore inadvisable to make a detailed report of the inspection until the second year of the exposure. The general results of the Pittsburg inspection as reported by the three committees[19]having supervision over the work, is, however, given herewith.
[19]J. H. James, Chairman Test Fence Committee, Carnegie Technical Schools.A. C. Rapp, Chairman Fence Committee, Pittsburg Branch Pennsylvania State Association of Master Painters.R. S. Perry, Director Scientific Section, Paint Manufacturers’ Association of the U. S.; H. A. Gardner, Asst. Director.
[19]J. H. James, Chairman Test Fence Committee, Carnegie Technical Schools.A. C. Rapp, Chairman Fence Committee, Pittsburg Branch Pennsylvania State Association of Master Painters.R. S. Perry, Director Scientific Section, Paint Manufacturers’ Association of the U. S.; H. A. Gardner, Asst. Director.
Pittsburg Test FencePittsburg Test Fence
Pittsburg Test Fence
During the inspection of the Pittsburg tests it was decided to condemn the lithopone panels on the fence, which consisted of formulas 21 to 27, including panels 151 to 164 in white, 131 to 144 in yellow, 109 to 122 in gray. Almost complete failure had taken place in every case where lithopone had been used. These lithopone tests were later on replaced by new tests which are described later in this book.
“Wood Most Valuable for Test.As on the Atlantic City Fence, the white pine panels afforded the best results and gives the best indication of the comparative wearing of the paints and affords no unfair condition, such as other woods might offer, to interfere with the test.
“Condition of Cypress.Cypress showed inferior conditions, except that it was more pronounced and more discoloration of the panels was noticed on this grade of wood, which seems to be extremely greasy in nature and difficult to properly prime, even when the paint used upon this wood contains a large percentage of volatile diluent.
“Removal of Lithopone Panels.The Joint Committees confirmed the previous recommendation to remove all the lithopone formulas, and they decided to remove the cypress and the yellow pine panels in every formula except in the white paints.
“It was decided to reassemble all the white pine panels and group them together for purposes of comparison, and in place of the panels condemned and removed, to substitute a series of new formulas, to further widen the scope of the tests.
“Ultimate Value of Mixed Paints.The results of the inspection conclusively show that a mixture of more than one prime white pigment, whether this mixture be alone or in combination with a small percentage of inert pigment, produces a paint far superior to a paint manufactured from one pigment alone.
“As a general statement of the comparative wearing of the paints, it might be said that the composite formulas are less advanced toward destruction than the paints made from single pigments such as lithopones, white leads and zinc oxides. It is not to be understood from this statement that it is the opinion of the committee that all of the composite formulas are of equal value or that all of them are to be recommended, but it is meant that the higher types, as evidenced by the appearance of the panels, are in the above relation to the single pigment paints.
Pittsburg Test Fence PanelsPanels on Pittsburg Test Fence
Panels on Pittsburg Test Fence
“Lithopone Destroyed Rapidly at Pittsburg.It was evident some time ago that the formulas containing large percentages of lithopone were rapidly failing, and their appearance was very much the same as those formulas of a similar type at Atlantic City. There seems, however, to be some difference in the way these formulas broke down; those on the Pittsburg Fence having shown the quicker destruction, possibly due to the action of the acid gases in the air upon the paint coating. This further confirms the statement that paint compositions containing such heavy percentages of lithopone and intended for outside use must be designed with relation to the particular uses of the product and to the climate in which they are to be used. It will also be necessary to consider more carefully the vehicle of the paints which are to be made of this pigment.
“Possible Value of Excluding Vehicle for Lithopone.It was the belief of the committee that much better paints containing lithopone could be designed by varying the percentages of the materials contained in the formulas, and it was suggested that a less penetrable vehicle, made more on the line of a varnish, and not as easily affected as straight linoxyn, should be experimented with in connection with these lithopone formulas.
“The success of certain European countries in using lithopone as a pigment, even in a very high percentage, may be due to the use of a special vehicle, and, if it is found in future tests that this material, which has been reported as well suited in Northern European climates, may be benefited and made of service by the addition of special oils and special vehicles, then this test would be of great value to the whole paint trade at large.
“Preliminary inspections were made on October 6th and later on December 12th, 1908, and a marked difference was observed at the two inspections in the wearing of the various formulas.
“The lapse of the two months between these inspections gave opportunity during which cold weather caused contraction of the paint film which had been previously subjected to the hot summer sun, and caused marked chalking of the white lead formulas. On October 6th this chalking was just commencing, while in the December inspection it was well advanced, and at the annual inspection, had proceeded to such an extent that the pigment had been washed from the panels representing those paints which had started early chalking.
“Panel 177, representing Zinc Lead, was found to be extremely dark in color throughout the coating and was more on the order of a grayish tint. It resisted all attempts to wash it down to a white surface. The panel, however, in other respects, was in fairly good condition.
“Condition of Corroded White Lead Panels.Panel 174, representing Type B Pure Basic Carbonate-White Lead, was very badly perished and discolored, and an examination of the surface showed very bad checking. Long continued washingwith a sponge removed a discolored surface and showed but a rather thin coating. Panel 175, representing Type C Pure Basic Carbonate-White Lead, showed most marked checking and was in very much the same condition as 174 and 176. Panel 176, representing Type A Pure Basic Carbonate-White Lead, was in the same condition as the Type B and C Basic Carbonate-White Leads.
“Condition of Sublimed White Lead.Panel 178, representing Sublimed White Lead (Basic Sulphate-White Lead,) was chalking, and the paint coat was somewhat disintegrated. The chalking present on this formula, however, showed that the disintegration of the paint coat had not taken place for several months after the Basic Carbonate-White Leads. This panel maintained good color, not being acted upon by sulphur gases.
“Blackening of Corroded White Lead.The black and gray formation on all the Basic Carbonate-White Lead panels was probably due to the action of sulphur gases which are present in the district immediate to Pittsburg, and which may cause the formation of black sulphide of lead.
“Possibly a general conclusion from all these panels might be described as a perishing of the paint coating, with the formation of sulphide of lead which to a certain extent protects the coating beneath it, but the perishing has proceeded to such an extent that the unaltered paint coating left is but a slight protection to the wood, being extremely thin.
“The committee resolved that the detailed observations of the panels could not be made and that they would not be justified in making detailed comparisons between the various formulas, giving the gloss, hardness, general condition, checking, etc. Precision in this work at such a time was impossible, and it was decided that a further period would have to elapse before such a detailed comparison could be made between the various blended or composite formulas on the fence.
“Report on Colors.It was resolved that at the next inspection of the Pittsburg Fence, portions of the original samples of the original paints used for the yellows and grays should be on hand, previously painted out on small panels for comparison for the deterioration of the colors on these same panels on the fence.
“An examination of the combination formula grays by the committee led to the general conclusion that those grays which did not contain a very large percentage of white lead were superior in their maintenance of tone and tint and general condition to any of the other grays upon the fence. However, the presence of umber, ochre, and red oxide in some of the grays which showed to the best advantage may account for their permanence of tone. Some of these grays were the so-called warm grays and were much darker in tone and tint than the ordinary drab which is generally applied.
“The straight pure Basic Carbonate-White Lead paints were not painted out in grays or yellow, the test upon this material being only in white.
“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.
“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.
“Superior Value of Composite Formulas.Some of the mixed leads, or so-called graded leads, which are combinations of white leads with other high-grade pigments and containing some inert pigments, were not deteriorated so far as the white lead formulas, and the general conclusion was that they were upward of six months behind the deterioration of the straight white leads, and this was confirmed by the presence of moderate chalking, showing an excellent repainting surface and a better thickness and condition of the paint coating.
“The same conclusions which were reached at Atlantic City, as to the best method of shellacking, obtained also on the Pittsburg Fence, namely, that application of the shellac to the wood previous to the first coat is the better method.
“Analysis of Paints.At the time of the painting of the fence a sample of each paint was placed in small friction top cans, carefully labeled, and sent to the Carnegie Technical Schools’laboratory for analysis. The analyses of these paints were made by members of the Test Fence Committee, representing the schools, and appear in this bulletin. The results obtained conform very closely to the formulas which were applied to the fence, a variance of only one or two per cent. being shown in the amount of the different pigments.”
Second Annual Inspection of Pittsburg Test Fence.The second annual inspection of the Pittsburg Test Fence was made on Thursday, May 7th, 1910. The panels in Pittsburg after having weathered for over two years presented an appearance which allowed the making of a detailed inspection, this having been found impossible during the first annual inspection. The inspection party[20]included those master painters who represented the Pittsburg Master Painters’ Association, who were in charge of the application of the paints in 1907, 1908, and 1909, together with the test fence committee from the faculty of the Carnegie Technical Schools, and representatives of the Scientific Section. A summary of the report issued by this committee follows:
[20]A. C. Rapp, Chairman, Test Fence Committee, Pittsburg Branch, Master Painters’ Association; John Dewar, member Fence Committee, Pittsburg Branch, Pennsylvania State Association of Master Painters; J. H. James, Chairman, Carnegie Technical Schools’ Test Fence Committee; John A. Schaeffer, member Test Fence Committee, Carnegie Technical Schools; Henry A. Gardner, Director Scientific Section, Paint Manufacturers’ Association of the U. S.
[20]A. C. Rapp, Chairman, Test Fence Committee, Pittsburg Branch, Master Painters’ Association; John Dewar, member Fence Committee, Pittsburg Branch, Pennsylvania State Association of Master Painters; J. H. James, Chairman, Carnegie Technical Schools’ Test Fence Committee; John A. Schaeffer, member Test Fence Committee, Carnegie Technical Schools; Henry A. Gardner, Director Scientific Section, Paint Manufacturers’ Association of the U. S.
“Two of the members of the inspection party have been impressed with the lumber lottery existing in some field tests, which have been conducted, and feel that when the object of a test is to determine the relative value of paints, such tests should be conducted on a standard grade of wood, such as white pine. The use of cypress, pitch pine, and other faulty woods, is often the cause of the failure of a paint, which on good wood would show up well. For this reason, only the white pine panels painted with white paints were considered in the inspection, the yellow pine panels and cypress panels having been thrown out of the test at last year’s inspection.
“Checking, cracking, and alligatoring on the painted surfaces were determined by using a magnifying glass. The degree of chalking existing was decided upon by using small pieces of blackfelt cloth, rubbing them against the surface of the panel; the degree of whiteness removed upon the cloth being indicative of the amount of chalking taking place. General condition was decided upon after carefully weighing the opinion of each member of the inspection party, as regards the general characteristics shown by each paint, such as checking, chalking, scaling, condition for repainting, hiding power, etc. The results have been charted and presented in this manner:[21]
[21]An endeavor was made to use uniform terms in reporting on each formula. In some cases it was necessary to bring out more forcibly the condition by the insertion of qualifying remarks.
[21]An endeavor was made to use uniform terms in reporting on each formula. In some cases it was necessary to bring out more forcibly the condition by the insertion of qualifying remarks.
Single vs Combination Pigment PaintPanel on Left Painted with Single Pigment Paint; Panel on Right Painted with Combination Pigment Paint. Photograph taken after Two Years’ Exposure on Pittsburg Test Fence
Panel on Left Painted with Single Pigment Paint; Panel on Right Painted with Combination Pigment Paint. Photograph taken after Two Years’ Exposure on Pittsburg Test Fence
“Conclusions Reached from the Test.The primary object of the test made at Pittsburg was to determine whether a combination paint, made of two or more pigments, would be equal or superior to single pigment paints. After one year’s exposure, the combination type of paint proved more durable than the single pigment paints.
“It was early apparent that the combination type of paints, that is, those paints made of more than one pigment, indicated in most cases very excellent wear, with a minimum of blackness and a general good condition of surface.
“Recommendation.On account of the peculiar conditions which obtain in and around Pittsburg, as exemplified by these tests, the committee finds, as a result thereof, that the best white paint for general exterior use is made of white lead combined with zinc oxide and a moderate percentage of inert pigments, such as silica, asbestine, or barytes.
“Some Peculiar Conditions Affecting the Tests.The inspectors were most impressed during the inspection by the blackness exhibited to such a high degree by certain panels, and the fair degree of whiteness by others. It is well known that in Pittsburg nearly all paints become darkened by the deposition on their surface of carbon particles emanating from the combustion of soft coal. Certain of the paints, however, presented fairly white surfaces, and it would thus appear that the extreme darkness shown by other paints was due to their composition. Corroded white lead when used alone was uniformly covered by black particles, and the higher the percentage of corroded white lead in a paint the darker was the surface. It was at first thought that this darkness was due to the softness of the white lead pigment or to its roughened surface, in causing adherence of soot particles. Sublimed white lead, however, which is also a soft pigment, chalked even more progressively than corroded white lead, but its surface was not rough, and presented a very white appearance. Scrapings from the different panels are being taken, and after a careful analysis the findings from the investigations will be reported by a member of the Inspection Committee.”
May 31, 1910