Paint Technology and Tests Part 16

[Ill.u.s.tration: AFTER WASHING]

[Ill.u.s.tration: Formula No. 38, Pittsburg

Basic Carbonate--White Lead Panels on Fence

BEFORE WASHING

Checking evident even through the outer covering of foreign matter.]

[Ill.u.s.tration: AFTER WASHING]

[Ill.u.s.tration: Formula No. 36, Pittsburg

Basic Carbonate--White Lead Panels on Fence

BEFORE WASHING

Peculiar network-like checking appearing through outer coat of impurities.]

[Ill.u.s.tration: AFTER WASHING]

[Ill.u.s.tration: Formula No. 40, Pittsburg]

[Ill.u.s.tration: Formula No. 45, Pittsburg]

=Results on Combination Pigment Paints.= It will be noticed that the checking on most of the combination pigment paints made of lead, zinc, and inert pigments, was moderate, and in many cases of a fine order. It has been observed that the percentage of zinc oxide in a paint is not always a criterion upon which future checking may be judged. Nor could it be said that the checking is dependent upon the percentage of basic carbonate-white lead added to the paint. However, it appears that scientific blending of the various pigments, with regard to their physical properties in oil, such as their strength and elastic limit, develops the greatest resistance to both cracking and checking.

Elasticity is vital, but strength must be combined therewith in order to prevent disruptions of the paint coating. Paint films made of certain inert pigments, when tested on the filmometer, were relatively high in strength, but relatively low in elasticity. Such pigments, when used in large percentage, form coatings which are hard and apt to crack. The use, however, of these pigments in moderate percentages seems very beneficial in overcoming the effect of using an excessive percentage of white lead, or of zinc oxide.

=Results on White Lead Paints.= The maximum checking was observed on the basic carbonate-white lead panels, the size of the checks in some cases being several times larger than those on the other panels.

On some of the basic carbonate-white leads the checking was of a very peculiar nature, consisting of very broad fissures in the paint coating, disclosing the wood surfaces beneath. The type of checking existing was also distinct in its structure, being hexagonal in shape. One of the most marked features shown by the basic carbonate-white lead films was the extreme roughness of their surfaces. This roughness is most likely due to the excessive chalking which had taken place.

=Results on Silica and Barytes Paints.= The checking of paints very high in silica resolved itself into fine hair-like lines which are generally lateral to each other, and indicate a cracked appearance. The checking of paints containing very high percentages of barytes was also of a distinct nature, being generally forked in appearance and of no definite striation.

=Surface Condition of Fume Pigment Paints.= The panels painted with basic sulphate-white lead (sublimed white lead) showed complete absence of checking. This was also true of the panels painted with zinc lead.

These are both fume products and are extremely fine in their physical size, which may account for this condition. Although zinc oxide is made in a similar manner, it gives a much harder paint coating than either of the afore-mentioned pigments, and presents a surface which develops considerable checking, generally of a medium order. The past theories regarding zinc oxide, in which it has been maintained that zinc oxide gives the maximum checking, are evidently incorrect, as the checking found on the zinc oxide panels was not as marked or deep as the checking on the basic carbonate-white lead panels; in fact, the checking might be more in the line of a cracking, possibly due to the brittle nature of the coating composed of straight zinc. This is especially true of zinc paints containing insufficient oil.

=The Importance of the Physical Nature of Pigments.= It appears that very fine grinding of materials, chosen for their characteristic fineness, with the absence of any unfavorable physical condition or chemical sensitiveness, are important factors in the making of a paint to resist cracking or checking. The purity of the essential materials, as well as the scientific compounding of these materials, with due regard to the law of minimum voids, are great factors which enhance the qualities of paints, greater, perhaps, than the variation of percentages of the various pigments which go to make up a paint.

CHAPTER XI

ADDITIONAL TESTS AT ATLANTIC CITY AND PITTSBURG

A series of new test panels to take the place of those panels which were condemned and subsequently removed from the Atlantic City and Pittsburg fences, were painted and exposed during June, 1909. These new test panels are of white pine, this wood having been selected by the joint inspection committee as offering the best condition for future tests.

The method used in painting these panels was the same as in the previous tests, together with the adoption of certain refinements in the reductions, application, etc. Thirty-six formulas were selected with careful regard to the percentage of components, including several paints containing lithopone combined with whiting and zinc oxide,[25] two pigments which gave promise of supporting the lithopone for outside use.

Some of these lithopone paints contained special vehicles which it was thought would prevent the destructive action which lithopone seems to have upon linseed oil. In order to obtain a criterion of the value of the new formulas applied, as against the wearing of straight white leads, the original white leads used in the previous tests were included, and other brands were added. Each formula was painted out in white, yellow, and gray, upon panels of white pine wood arranged in sequence upon the fence, and properly identified. The customary opacity test, in the form of a small black square, was stencilled over the priming coat of each panel, as in the former tests. The composition of the vehicle in all the new tests was standard, using pure linseed oil with a small percentage of turpentine drier. The tints used in each formula were secured at the time of application by the use of standard colors, lampblack, and medium chrome yellow, using an approximate amount for each formula.

[25] A brief study of the theory of solutions (See Cushman and Gardner on "Corrosion and Preservation of Iron and Steel"), involving the modes of iron formation, will be invaluable to the student who is inquiring into the cause of the peculiar fogging of lithopone, with the idea in view of correcting this evil by physical or chemical treatment. Inasmuch as our observations thus far have led us to believe that the fogging of lithopone takes place in the presence of moisture, with the contributory and necessary action of chemically active rays from the sun or other source, it is fair to a.s.sume that under these conditions the insoluble molecule of zinc sulphide and barium sulphate reverts by intricate molecular disturbance and ionization back to the soluble barium sulphide and zinc sulphate from which the lithopone is formed by metathesis. If this be true, then the acid nature of these soluble salts is no doubt combated and overcome at the moment of formation by the basic nature of zinc oxide and calcium carbonate, which tend to ionize to an alkaline reaction.

The value of zinc oxide and calcium carbonate in lithopone paints as detergents of blackness, has been demonstrated at both Atlantic City and Pittsburg." H. A. G.

[Ill.u.s.tration: Section of Fence Showing New Panels Recently Placed]

[Ill.u.s.tration: Appearance of 1909 Tests]

An inspection of these new tests was made during June, 1910, and the results of the inspection are shown on pages 178 to 181. The results of the inspection prove that it is unsafe to use lithopone in a paint containing white lead of any type, early darkening and failure being shown in every case where such a combination existed. The formulas in the new test, which were properly balanced and which had a low percentage of lithopone combined with zinc oxide and whiting, presented in some cases very good surfaces. A rough, sandy surface, however, was shown where lithopone was used in any great quant.i.ty.

TESTS INAUGURATED IN 1909

RESULTS OF INSPECTION OF ATLANTIC CITY TEST FENCE, MAY, 1910

===============================================+ FORMULAS | --+-----------------------+--------------------+ F | | | o | | | r |Basic Carbonate | | m |White Lead | | u | |Zinc Oxide | | l | | |Basic Sulphate | | a | | |White Lead | INERT PIGMENTS | | | | |Precipi- +--------------------+ N | | | |tated |Calcium Carbonate | u | | | |White Lead | |Silica | m | | | | |Zinc | | |Asbestine | b | | | | |Lead | | | |China Clay| e | | | | | |Li- | | | | |Barytes| r | | | | | |tho-| | | | | |Blanc| | | | | | -pone| | | | | +-Fixe| --+----+--+---+---+---+---+--+---+--+--+--+----+ | % | %| %| %| %| %| %| %| %| %| %| % | 1| -- |--| 45| --| --| 40|15| --|--|--|--| -- | 2| -- |--| 45| --| --| 40|--| 15|--|--|--| -- | 3| -- |45| --| --| --| 45|10| --|--|--|--| -- | 4| -- |--| 45| --| --| 45|10| --|--|--|--| -- | 5| -- |40| --| --| --| 40|20| --|--|--|--| -- | 6| -- |--| 45| --| --| 35|--| --|20|--|--| -- | 7| 50 |--| --| --| 36| --|--| --| 2| 8| 4| -- | 8| -- |--| 50| --| --| 36|--| --| 2| 8| 4| -- | 9| -- |--| 50| --| --| 36|--| --| 2|--|12| -- | 10| -- |36| 50| --| --| --|--| --| 2| 8| 4| -- | 11| 28 |55| --| --| --| --|--| --| 3|--| 7| 7 | 12| -- |55| 28| --| --| --|--| --| 3|--| 7| 7 | 13| -- |60| --| --| --| 30|10| --|--|--|--| -- | 14| -- |30| 30| --| --| 30|10| --|--|--|--| -- | 15| -- |--| 60| --| --| 30|--| --|10|--|--| -- | 16| -- |--| --| --| --|100|--| --|--|--|--| -- | 17| -- |--| --| --| --|100|--| --|--|--|--| -- | 18| 33 |33| --| --| --| --|--| 17|--|17|--| -- | 19| 34 |33| --| --| --| --|--| 33|--|--|--| -- | 20| 34 |33| --| --| --| --|--| --|--|33|--| -- | 21|100 |--| --| --| --| --|--| --|--|--|--| -- | |[26]| | | | | | | | | | | | 22|100 |--| --| --| --| --|--| --|--|--|--| -- | 23|100 |--| --| --| --| --|--| --|--|--|--| -- | 24| -- |--|100| --| --| --|--| --|--|--|--| -- | 25| -- |--| --| --|100| --|--| --|--|--|--| -- | 26| -- |--| --|100| --| --|--| --|--|--|--| -- | 27|100 |--| --| --| --| --|--| --|--|--|--| -- | 28|100 |--| --| --| --| --|--| --|--|--|--| -- | 29| 24 |45| 13| --| --| --|--| --|18|--|--| -- | 30| 45 |--| --| --| --| 40|15| --|--|--|--| -- | 31| 45 |--| --| --| --| 40|--| 15|--|--|--| -- | 32| 45 |--| --| --| --| 35|--| --|20|--|--| -- | 33| 50 |--| --| --| --| 36|--| --| 2|--|12| -- | 34| 75 |--| 25| --| --| --|--| --|--|--|--| -- | 35| 50 |--| 50| --| --| --|--| --|--|--|--| -- | 36| -- |--| --| --| --| --|--|100|--|--|--| -- | ==+====+==+===+===+===+===+==+===+==+==+==+====+

[26] This pigment on a.n.a.lysis proved to be zinc lead.

==+===============================================+== F | | o | | r | | P m | | a u | | n l | | e a | | l | | N | | N u | | u m | REPORT OF INSPECTION | m b |---------+---------+----------------+----------+ b e |CHALKING |CHECKING |GENERAL |REMARKS | e r | | |CONDITION | | r --+---------+---------+----------------+----------+-- 1|None |None |Rough surface, | | 1 | | |but fair for re-| | | | |painting | | 2|None |None |Fair; rough sur-| | 2 | | |face and slight-| | | | |ly dark | | 3|Very |Very |Good; very white| | 3 |slight |slight |surface | | 4|None |None |Rough surface | | 4 | | |and slightly | | | | |dark | | 5|Very |Very |Good; very white| | 5 |slight |slight |surface | | 6|None |None |Rough surface; | | 6 | | |dark | | 7|None |Very |Good | | 7 | |slight | | | | |lateral | | | | |checking | | | 8|Heavy |Slight |Excellent; very | | 8 | | |white | | 9|Heavy |Some |Excellent; very | | 9 | | |white | | 10|None |Slight |Good | |10 11|None |Slight |Good; slightly | |11 | | |dark | | 12|None |Slight |Good | |12 | |lateral | | | 13|Very |Consider-|Fair | |13 |slight |able | | | | |lateral | | | | |running | | | | |along | | | | |grain of | | | | |wood | | | 14|Very |Consider-|Fair | |14 |slight |able | | | | |lateral | | | | |running | | | | |along | | | | |grain of | | | | |wood | | | 15|Heavy |Slight |Fair | |15 | |lateral | | | | |checking | | | 16|Heavy |Consider-|Dark color; | |16 | |able |rough surface | | 17|Consider-|Medium |Better than No. | |17 |able | |16; not as rough| | | | |or dark | | 18|Very |None |Good | |18 |slight | | | | 19|Very |Slight |Good | |19 |slight | | | | 20|Very |None |Good | |20 |slight | | | | 21|Slight |Slight |Fair; rough | |21 | | |surface | | 22|Very |Lateral |Fairly good | |22 |slight |cracking | | | 23|Medium |Lateral |Fair | |23 | |cracking | | | 24|Slight |Slight |Good for | |24 | |cracking |repainting | | 25|Medium |None |Good surface | |25 26|Heavy |Slight |Fair; surface | |26 | |cracking |rough & dark | | 27|Heavy |Lateral |Fair | |27 | |cracking | | | 28|Medium |Consider-|Poor; very | |28 | |able |rough, dark | | | | |surface | | 29|Slight |None |Good | |29 30|Heavy |Heavy |Poor | |30 | |checking | | | | |and alli-| | | | |gatoring | | | 31|None |Alliga- |Rough surface; | |31 | |toring |dark | | 32|Slight |Medium |Dark and rough | |32 | | |surface | | 33|Consider-|Slight |Poor; dark | |33 |able | |surface | | 34|None |None |Fair; dark | |34 | | |surface | | 35|None |Slight |Fair; rough | |35 | | |surface | | 36|Extremely|Medium |Fair |Vehicle |36 |bad | | |disinte- | | | | |grated; | | | | |spotted in| | | | |places | ==+=========+=========+================+==========+==

TESTS INAUGURATED IN 1909

RESULTS OF INSPECTION OF PITTSBURG TEST FENCE, MAY, 1910

===============================================+ FORMULAS | --+-----------------------+--------------------+ F | | | o | | | r |Basic Carbonate | | m |White Lead | | u | |Zinc Oxide | | l | | |Basic Sulphate | | a | | |White Lead | INERT PIGMENT | | | | |Precipi- +--------------------+ N | | | |tated |Calcium Carbonate | u | | | |White Lead | |Silica | m | | | | |Zinc | | |Asbestine | b | | | | |Lead | | | |China Clay| e | | | | | |Li- | | | | |Barytes| r | | | | | |tho-| | | | | |Blanc| | | | | | -pone| | | | | --Fixe| --+----+--+---+---+---+---+--+---+--+--+--+----+ | % | %| %| %| %| %| %| %| %| %| %| % | 1| -- |--| 45| --| --| 40|15| --|--|--|--| -- | 2| -- |--| 45| --| --| 40|--| 15|--|--|--| -- | 3| -- |45| --| --| --| 45|10| --|--|--|--| -- | 4| -- |--| 45| --| --| 45|10| --|--|--|--| -- | 5| -- |40| --| --| --| 40|20| --|--|--|--| -- | 6| -- |--| 45| --| --| 35|--| --|20|--|--| -- | 7| 50 |--| --| --| 36| --|--| --| 2| 8| 4| -- | 8| -- |--| 50| --| --| 36|--| --| 2| 8| 4| -- | 9| -- |--| 50| --| --| 36|--| --| 2|--|12| -- | 10| -- |36| 50| --| --| --|--| --| 2| 8| 4| -- | 11| 28 |55| --| --| --| --|--| --| 3|--| 7| 7 | 12| -- |55| 28| --| --| --|--| --| 3|--| 7| 7 | 13| -- |60| --| --| --| 30|10| --|--|--|--| -- | 14| -- |30| 30| --| --| 30|10| --|--|--|--| -- | 15| -- |--| 60| --| --| 30|--| --|10|--|--| -- | 16| -- |--| --| --| --|100|--| --|--|--|--| -- | 17| -- |--| --| --| --|100|--| --|--|--|--| -- | 18| 33 |33| --| --| --| --|--| 17|--|17|--| -- | 19| 34 |33| --| --| --| --|--| 33|--|--|--| -- | 20| 34 |33| --| --| --| --|--| --|--|33|--| -- | 21|100 |--| --| --| --| --|--| --|--|--|--| -- | 22|100 |--| --| --| --| --|--| --|--|--|--| -- | |[27]| | | | | | | | | | | | 23|100 |--| --| --| --| --|--| --|--|--|--| -- | 24| -- |--|100| --| --| --|--| --|--|--|--| -- | 25| -- |--| --| --|100| --|--| --|--|--|--| -- | 26| -- |--| --|100| --| --|--| --|--|--|--| -- | 27|100 |--| --| --| --| --|--| --|--|--|--| -- | 28|100 |--| --| --| --| --|--| --|--|--|--| -- | 29| 24 |45| 13| --| --| --|--| --|18|--|--| -- | 30| 45 |--| --| --| --| 40|15| --|--|--|--| -- | 31| 45 |--| --| --| --| 40|--| 15|--|--|--| -- | 32| 45 |--| --| --| --| 35|--| --|20|--|--| -- | 33| 50 |--| --| --| --| 36|--| --| 2|--|12| -- | 34| 75 |--| 25| --| --| --|--| --|--|--|--| -- | 35| 50 |--| 50| --| --| --|--| --|--|--|--| -- | 36| -- |--| --| --| --| --|--|100|--|--|--| -- | ==+====+==+===+===+===+===+==+===+==+==+==+====+

[27] This pigment on a.n.a.lysis proved to be zinc lead.

==+===============================================+== F | | o | | r | | P m | | a u | | n l | | e a | | l | | N | | n u | | u m | REPORT OF INSPECTION | m b +---------+---------+----------------+----------+ b e |CHALKING |CHECKING |GENERAL |REMARKS | e r | | |CONDITION | | r --+---------+---------+----------------+----------+-- | | | | | 1|Consider-|Slight |Fair |Dark in | 1 |able | | |places. | | | | |Diffused | 2|Slight |Bad |Fair |Dark in | 2 | | | |places | 3|Medium |None |Good |Darkening | 3 | | | |shown in | | | | |places | 4|Consider-|None |Good |Medium | 4 |able | | |dark | 5|Slight |None |Good |No exces- | 5 | | | |sive dark-| | | | |ness | 6|Medium |Slight |Good |Surface | 6 | | | |fairly | | | | |white | 7|Medium |None |Excellent |Whitest | 7 | | | |surface of| | | | |new tests | 8|Extremely|Slight |Fair |Surface | 8 |bad | | |darkening | 9|Extremely|Slight |Fair |Not as bad| 9 |bad | | |as No. 8 | 10|Slight |None |Good |Excellent |10 | | | |surface; | | | | |very white| 11|Slight |None |Excellent |Surface |11 | | | |fairly | | | | |white; | | | | |thin soot | 12|Medium |None |Good |Surface |12 | | | |white | 13|Medium |Very bad |Fair |Slight |13 | |in spots | |darkening | 14|Heavy |Consider-|Fair |Slight |14 | |able | |darkening | 15|Extremely|Slight |Fair |Fairly |15 |bad | | |white | 16|Extremely|Advanced |Bad |Surface |16 |bad |and deep | |rough with| | | | |consider- | | | | |able dis- | | | | |integra- | | | | |tion and | | | | |much dark-| | | | |ness | 17|Not as |Less ad- |Fair |Not as |17 |bad as |vanced | |dark as | |No. 16 |than No. | |No. 16; | | |16 | |slightly | | | | |mottled in| | | | |places; | | | | |buff color| 18|Very |Practi- |Fair |Surface |18 |slight |cally | |white | | |none | | | 19|Very |None |Good |Surface |19 |slight | | |fairly | | | | |white | 20|None |None |Good |Surface |20 | | | |fairly | | | | |white | 21|Slight |Slight |Fair |Surface |21 | | | |very rough| | | | |and dark | 22|Medium |Slight |Fair |Surface |22 | | | |fairly | | | | |white | 23|Slight |Bad |Fair |Surface |23 | | | |rough and | | | | |darkest on| | | | |fence | 24|Bad |None |Good |Surface |24 | | | |white | 25|Slight |None |Good |Fairly |25 | | | |white | | | | |surface | 26|Medium |Slight |Fair |Rough and |26 | | | |very dark;| | | | |chalking | | | | |is dis- | | | | |rupting | | | | |black | | | | |coating | 27|Medium |Slight |Good |Surface |27 | | | |fairly | | | | |white | 28|Medium |Deep; |Poor |Surface |28 | |evident | |rough and | | |without | |very dark | | |gla.s.s | | | 29|Slight |Slight |Good |Very white|29 | | | |surface | 30|None |Slight |Fair |Color dark|30 31|Very |Advanced |Fair |Color very|31 |slight | | |dark | 32|Extremely|Consider-|Fair |Color very|32 |slight |able | |dark; | | | | |rough | | | | |surface | 33|Extremely|Slight |Fair |Surface |33 |slight | | |dark and | | | | |rough | 34|Slight |Deep |Fair |Surface |34 | | | |medium | | | | |dark | 35|Consider-|Slight |Fair |Surface |35 |able | | |medium | | | | |dark | 36|Extremely|None |Fair |Vehicle |36 |bad | | |disinte- | | | | |grated, | | | | |leaving | | | | |very | | | | |white, | | | | |chalked | | | | |surface of| | | | |pigment | ==+=========+=========+================+==========+==

CHAPTER XII

NORTH DAKOTA PAINT TESTS

An inspection of the original test fence, erected and painted by the North Dakota Agricultural College, on the grounds of the agricultural Experiment Station at Fargo, was made by the inspection committee[28]

representing the Paint Manufacturers' a.s.sociation of the United States, on the 19th and 20th of November, 1909. The fence was erected in 1906 and painted with commercial paints, procured in the open market. The east side of the fence was built of soft pine and cedar weather-boarding, such as is almost universally used on houses in that locality, presenting a very good surface for test purposes, while the west side was built largely of flat trimmed boards of hard pitch pine which, unfortunately, contained knots, pitch pockets, and uneven surfaces, causing to a greater or lesser extent cracking, scaling, and bad general results on all paints applied thereto.

[28] Henry A. Gardner, Director Scientific Section, Educational Bureau, Paint Manufacturers' a.s.sociation of U. S.; George Butler, Master Painter; Charles Macnichol, Master Painter.

The fences built in 1907 and 1908 at the suggestion of the Paint Manufacturers' a.s.sociation, were inspected on the 20th, 21st, and 22nd of November, 1909, and the detailed results of the inspection of all these fences follow in this report. The same general conclusions as to the woods represented in the 1906 fence also apply to the 1907 and 1908 fences, and because of the general bad quality of wood used on the western exposure of all fences, the detailed reports were made only from an examination of the eastern side of the fences, both on cedar and soft pine.

The following general summary of the inspection and its results applies to all the test fences on the grounds of the college and is the unanimous conclusion drawn by the inspectors from this work:

[Ill.u.s.tration: North Dakota Test Fences]