Paint Technology and Tests Part 13

17| |Some |Fair | 18|Hard Matt |Moderate |Medium | 19|Hard Matt |Slight |Very Little| 20| |Very Little|Medium | 33| | |Good |Rough surface.

34|Evident |Slight |Egg Sh.e.l.l | 35|Matt | |Egg Sh.e.l.l | 36|Very |Bad |Egg Sh.e.l.l |Same as 177, but |Apparent | | |checking not so bad.

37|Very |Bad |Egg Sh.e.l.l |Same as 177 but wood |Apparent | | |shows more plainly.

38|Bad |Bad |Egg Sh.e.l.l |Cracking and peris.h.i.+ng evident.

39| |Some |Good | 40| |Consider- |Egg Sh.e.l.l | | |able | | 45|Very Evi- | |High | |dent | | | 46|Some | |Good | 47|Apparent | |Good |Indication of scaling.

"An inspection of the white lead paints on the fence indicated in every instance a rough, chalked, and disintegrated surface that seemed to be well worn, in some cases nearly to the wood. The strongly oxidizing air of the seacoast is probably responsible for the early decay of this pigment.

"It was observed that the combination type of paint showed better hiding power than white lead, over the black crosses placed on the priming coat of each panel, as a hiding power test.

[Ill.u.s.tration: Front of Fence showing Present Rearrangement of Panels]

TESTS INAUGURATED IN 1907

CHART OF RESULTS OF SECOND ANNUAL INSPECTION OF ATLANTIC CITY TEST FENCE, MAY, 1910

=========================================================+ FORMULAS | --+------------------------+-----------------------------+ F | | INERT PIGMENTS | o | +-----------------------------+ r |Basic Carbonate |Calcium | m |White Lead |Carbonate | u | |Zinc Oxide | |Calcium | l | | |Basic | |Sulphate | a | | |Sulphate | | |Magnesium | | | |White Lead| | |Silicate | N | | | |Zinc | | | |Barium | u | | | |Lead | | | |Sulphate | m | | | |White| | | | |Silica | b | | | --+ | | | | | |Blanc| e | | | | | | | | | | Fixe| r | | | | | | | | | --+ | --+------+------+------+---+-----+--+----+-----+-----+---+ | % | % | % | %| % | %| % | % | % | %| 1| 30 | 70 | -- | --| -- |--|-- |-- |-- | --| 2| 50 | 50 | -- | --| -- |--|-- |-- |-- | --| 3| 20 | 50 | 20 | --|10 |--|-- |-- |-- | --| 4| 48.5 | 48.5 | -- | --| 3.0 |--|-- |-- |-- | --| 5| 22 | 50 | -- | --| 2 |--|26 |-- |-- | --| 6| -- | 64 | -- | --| -- |--|-- |36 |-- | --| 7| 37 | 63 | -- | --| -- |--|-- |-- |-- | --| 8| 38 | 48 | -- | --| -- |--|-- |-- |14 | --| 9| -- | 73 | -- | --| 2 |--|-- |-- |25 | --| 10| 44 | 46 | -- | --| 5 |--| 5 |-- |-- | --| 11| 50 | 50 | -- | --| -- |--|-- |-- |-- | --| 12| 60 | 34 | -- | --| -- | 6% Inert Pigment | --| 13| -- | 27 | 60 | --| 3 |--|10 |-- |-- | --| 14| 25 | 25 | 20 | --| 5 |25|-- |-- |-- | --| 15| 20 | 40 | -- | 30|10 |--|-- |-- |-- | --| 16| 33 | 33 | -- | --| -- |--|-- |34 |-- | --| 17| 40 | 40 | -- | --| -- |--| 3 |13 |-- | 4| 18| 75 | 25 | -- | --| -- |--|-- |-- |-- | --| 19| -- | 25 | 75 | --| -- |--|-- |-- |-- | --| 20| 67.0 | 19.5 | -- | --|10.0 |--| 3.5|-- |-- | --| 33| 15 | 30 | 25 | --| -- |--|-- |-- |30 | --| 34| 38.95| 33.58| 4.81| --|19.48|--|-- | 1.59| 1.59| --| 35| 37.51| 25.87| 7.84| --|20.36|--|-- | 4.21| 4.21| --| 36|100 | -- | -- | --|-- |--|-- |-- |-- | --| 37|100 | -- | -- | --|-- |--|-- |-- |-- | --| 38|100 | -- | -- | --| -- |--|-- |-- |-- | --| 39| -- | -- | -- |100| -- |--|-- |-- |-- | --| 40| -- | -- |100 | --| -- |--|-- |-- |-- | --| 45| -- | 90 | -- | --|10 |--|-- |-- |-- | --| 46| -- | 61 | -- | --| -- |--|-- |39 |-- | --| 47| -- |100 | -- | --| -- |--|-- |-- |-- | --| ==+======+======+======+===+=====+==+====+=====+=====+===+

==+========================================+=== F | | o | | r | | P m | | a u | | n l | | e a | | l | REPORT OF INSPECTION | N +-----------+------------+------+--------+ N u | | |GENE- | | u m | | |RAL | | m b | | |CON- | | b e | | |DI- | | e r |CHALKING |CHECKING |TION |REMARKS | r --+-----------+------------+------+--------+--- 1|Very slight|Very slight |Good |-- | 1 2|Medium |Slight |Very |-- | 3 | | |good | | 3|Medium |Slight |Good |-- | 5 4|Very slight|Slight |Good |-- | 7 5|Slight |Slight |Good |-- | 9 6|Very slight|Slight |Good |-- | 11 7|Medium |Slight |Good |-- | 13 8|Slight |Very slight |Good |-- | 15 9|Very bad |Deep, with |Poor |-- | 17 | |scaling | | | 10|Heavy |Deep |Medium|-- | 19 11|Medium |Medium |Fair |-- | 21 12|Medium |Deep |Fair |-- | 23 13|Medium |Slight |Very |-- | 25 | | |good | | 14|Medium |Lateral |Fair |-- | 27 15|Slight |Visible with|Poor |-- | 29 | |naked eye | | | 16|Slight |Slight |Good |-- | 31 17|Medium |Slight |Good |-- | 33 18|Medium |Slight |Very |-- |145 | | |good | | 19|Consider- |Deep |Good |-- |147 |able | | | | 20|Medium |Slight |Good |-- |149 33|Medium |Slight |Very |-- |176 | | |good | | 34|Slight |Slight |Good |-- |175 | |lateral | | | 35|Slight |Lateral |Good |-- |180 36|Consider- |Heavy |Fair |Rough |181 |able | | |surface | 37|Consider- |Heavy and |Poor |Rough |182 |able |deep | |surface | 38|More than |Very deep |Poor |-- |177 |Panel no. | | | | |182 | | | | 39|Consider- |Very slight |Good |-- |178 |able | | | | 40|Heavy |Slight |Good |-- |168 45|Slight |Slight |Good |-- |170 46|Slight |Medium |Fair |-- |169 47|None |Very deep |Poor |-- |172 ==+===========+============+======+========+===

"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 r.e.t.a.r.ds 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."

CHAPTER IX

RESULTS OF PITTSBURG TESTS

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[22] having supervision over the work, is, however, given herewith.

[22] J. H. James, Chairman Test Fence Committee, Carnegie Technical Schools.

A. C. Rapp, Chairman Fence Committee, Pittsburg Branch Pennsylvania State a.s.sociation of Master Painters.

R. S. Perry, Director Scientific Section, Paint Manufacturers'

a.s.sociation of the U. S.; H. A. Gardner, a.s.st. Director.

[Ill.u.s.tration: 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 p.r.o.nounced 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 rea.s.semble all the white pine panels and group them together for purposes of comparison, and in place of the panels condemned and removed, to subst.i.tute 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.

[Ill.u.s.tration: 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 was.h.i.+ng with 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 peris.h.i.+ng of the paint coating, with the formation of sulphide of lead which to a certain extent protects the coating beneath it, but the peris.h.i.+ng 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.

[Ill.u.s.tration: Whiteness of Sublimed White Lead

Darkness of Corroded White Lead