Paint Technology and Tests Part 18

[Ill.u.s.tration: 7. Formula No. 13, Panel 19, on 1907 Fence]

[Ill.u.s.tration: 8. Formula No. 19, Panel 28. Broad, Deep Checking on Corroded White Lead on 1907 Fence]

[Ill.u.s.tration: 9. Formula No. 24, Panel 36, on 1907 Fence. Good Condition. Surface Checking Only]

[Ill.u.s.tration: 10. Formula No. 25, Section 37, on 1907 Fence. Good Condition. Surface Checking Only]

[Ill.u.s.tration: 11. Formula No. 8, Panel 12, on 1907 Fence]

[Ill.u.s.tration: 12. Formula No. 10, Panel 15, on 1907 Fence]

[Ill.u.s.tration: 13. Panel No. 34, Formula 23, on 1907 Fence. Deep Checking on Corroded White Lead]

[Ill.u.s.tration: 14. Test No. 13 on 1906 Fence. White Spots Show Paint Left on Wood. Balance of Paint Split and Disintegrated from Surface]

[Ill.u.s.tration: 15. Test No. 6 on 1906 Fence. Surface Checking Only]

[Ill.u.s.tration: 16. Test No. 2, 1906 Fence. Sublimed White Lead]

[Ill.u.s.tration: 17. Cracks in Test No. 15 on 1906 Fence]

[Ill.u.s.tration: 18. Effect of Cracking on Hard Pine, Causing Splitting of Painting Coating]

[Ill.u.s.tration: 19. Formula No. 22, Section 23, 1907 Fence. Cracks in Paint Coating, Caused by Cracks in Wood; Coating Otherwise in Good Condition]

[Ill.u.s.tration: 20. Test No. 8, on 1906 Fence. Surface Checking Only]

[Ill.u.s.tration: 21. Combination Cracking and Checking on Section 69, on 1908 Fence]

[Ill.u.s.tration: 22. Cracks in Paint Coating, Caused by Cracking of Hard Pine Wood]

[Ill.u.s.tration: 23. Section 65 on 1908 Fence. Showing Early Breakdown of Corroded White Lead]

CHAPTER XIII

TENNESSEE PAINT TESTS

=Location and Object of Tests.= On September 15, 1910, the erection of a wooden test fence was completed on the State Fair Grounds at Nashville, Tenn. Upon this fence were exposed forty-two samples of white paint, the object of the test being to determine whether the combination type of formula is superior to the single pigment type in the southern plateau, of which Nashville is the centre.

=Construction of Tests.= The construction and outline of these tests differ somewhat from those conducted at Atlantic City and elsewhere by the Scientific Section. The fence frame is 150 feet long, being made of 6-inch bevelled girders supported three feet from the ground by 4-inch posts set six feet apart. Upon this girder were placed a series of forty-two test panels supported at top and bottom with weather strips and braces. The test panels used were 40 inches high, 30 inches wide, and one inch thick, being made of the highest grade white pine, tongued and grooved together, and protected on the edges by weather strips projecting from the surface of the panels. Each panel was painted on both sides with the same paint, thus giving an eastern and western exposure, the fence running north and south. The formulas used in the test vary in their percentage composition, being made up in some cases of single pigments, and again with combinations of the opaque white pigments, with and without certain percentages of the crystalline or inert pigments. The paints were applied under the supervision of prominent master painters and a committee representing the Scientific Section and other technical organizations.

Other field tests have shown that the sap and knots in hard-grained woods, such as yellow pine, cypress, etc., have been the cause of the failure of even the best paints, and that all tests should be conducted upon soft woods, such as white pine and poplar, if definite results are to be obtained. Paints tinted with ochre, chrome yellow, lampblack, iron oxide, etc., have shown on the other field tests which have been conducted at Atlantic City, Pittsburg, and Fargo the value of these pigments in giving to the paints increased wearing properties. On the Southern Test Fence, therefore, all the formulas were ground in white only and placed upon white pine so as to make the test primarily one to determine the value of the various white pigments upon good wood.

[Ill.u.s.tration: Tennessee Test Fences]

=Oil and Thinner Tests.= Upon one series of panels on the fence was placed one of the formulas which had given universal satisfaction on the various test fences in the past, and this formula was made up with various oils other than linseed oil, in order to determine the value of these oils as painting materials. For instance, the vehicle part of the one formula referred to is made up of 50% linseed oil and 50% soya bean oil, and again 50% linseed oil and 50% rosin oil, etc., an effort being made to test out a few of the available semi-drying oils.

The same formula referred to was ground in pure linseed oil and subjected to a series of tests where it has been thinned for application as priming and second coats with a series of wood turpentines obtained from the United States Forest Products Laboratory at Madison, Wis. These turpentines were made from southern pine stumps and sawdust, and they vary greatly in their properties. Some were objectionable in odor, while others were of excellent quality, having an odor almost equal to that of pure gum spirits.

[Ill.u.s.tration: Views of Fence]

One product under test on the Southern Test Fence is pine oil, a high boiling point product obtained from the manufacture of wood turpentine from sawdust. This oil has a boiling point of over 210 degrees Centigrade as against the 150 degrees of ordinary gum spirits. It is almost water white and has the same penetrating qualities as the pure gum spirits; when mixed with 50% linseed oil forming a paint oil of extremely light color, that produces a semi-flat paint of great whiteness.

=Reductions and Application.= Formulas No. 1 to No. 37 were all ground in pure refined linseed oil. They were made in the form of semi-paste and then thinned down with sufficient refined linseed oil so that each would have a relative viscosity. To each formula was then added a sufficient amount of pure lead and manganese linoleate drier to give proper drying qualities. On thinning for the priming coat, one pint of turpentine was added to each gallon of paint. For the second coat, one-half pint turpentine and one-half pint refined linseed oil were added to each gallon. For the third coat work, reduction was made with one pint of refined linseed oil.

In the case of formulas 31 to 37, reductions were the same, except that a series of specially prepared wood turpentines were used in place of the pure gum spirits used in formulas 1 to 31.

Formulas 38 to 41, as will be shown, were ground in equal parts of the oils tested. These formulas, however, were all thinned for application with pure gum spirits of turpentine, and the respective vehicle in which they were ground.

No inspection of the Tennessee Test Fence has yet been made. The formulas tested are as follows:

FORMULAS FOR SOUTHERN TEST FENCE

VEHICLE: _Bleached Linseed Oil with Lead and Manganese Linoleate Drier_.

Formula No.

1 [30]Corroded white lead 100% 2 [30]Sublimed white lead 100% 3 Zinc oxide XX 100% 4 Zinc lead white 100% 5 Leaded zinc 65%, corroded white lead 35% 6 [30]Corroded white lead 100% 7 [30]Corroded white lead 100%

[30] Corroded White Lead is the Basic Carbonate of Lead. Sublimed White Lead is the Basic Sulphate of Lead.

No. 8

Corroded white lead 85% Zinc oxide 15% ---- 100%

No. 9

Corroded white lead 65% Zinc oxide 35% ---- 100%

No. 10

Corroded white lead 50% Zinc oxide 50% ---- 100%

No. 11

Corroded white lead 40% Zinc oxide 60% ---- 100%

No. 12

Corroded white lead 30% Zinc oxide 70% ---- 100%

No. 13

Corroded white lead 45% Zinc oxide 45% Silica 10% ---- 100%