[Illustration: AFTER WASHING]
[Illustration: Formula No. 38, Pittsburg
Basic Carbonate--White Lead Panels on Fence
BEFORE WASHING
Checking evident even through the outer covering of foreign matter.]
[Illustration: AFTER WASHING]
[Illustration: Formula No. 36, Pittsburg
Basic Carbonate--White Lead Panels on Fence
BEFORE WASHING
Peculiar network-like checking appearing through outer coat of impurities.]
[Illustration: AFTER WASHING]
[Illustration: Formula No. 40, Pittsburg]
[Illustration: 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 assume 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.
[Illustration: Section of Fence Showing New Panels Recently Placed]
[Illustration: 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 quantity.
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 analysis 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 analysis 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 glass 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' Association 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' Association 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' Association, 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:
[Illustration: North Dakota Test Fences]