Paint Technology and TestsGardner, Henry A. (Henry Alfred)
Science
Paint Technology and Tests
Gardner, Henry A. (Henry Alfred)
Paint
=Results on Various Woods.= On the Atlantic City Fence all the tests
made on yellow pine and cypress were found to be in an unsatisfactory
condition for a report, for in every case the sap and small knots
contained in such wood had a very bad effect upon the paint, causing
peeling and scaling. The white pine panels were in very much better
condition, and it was therefore decided to make the inspection entirely
from the white pine panels and in the future to remove the yellow pine
and the cypress panels from the fence and from the test. The Committee
advised that all future tests be made on white pine, as it is obviously
unfair to use anything but the highest grade wood for a paint test in
which the desire is to determine the comparative wearing value of
pigments.
NOTE.--Recent tests have shown that Cypress may be successfully
painted when the priming coat of paint is thinned with Benzol
(Solvent Naphtha).
[Illustration: Panels on Atlantic City Fence Two Lower Sets of Panels
are painted with Lithopone Paints. Rapid Failure shown]
[Illustration: Panels on Atlantic City Fence]
[Illustration: Panels on Atlantic City Fence
Two Lower Sets of Panels are Painted with Combination Pigment Paints.
Excellent Results shown]
=Paints Containing Lithopone.= One of the most striking exhibitions of
paint disintegration in the whole test was the failure of nearly all the
lithopone formulas tested. At the time these formulas were suggested for
the test, various European technical journals had advocated the use of
lithopone in large percentage for paints to be used on exterior
surfaces. Good results had been obtained in the northwestern section of
Europe, with this pigment in certain mixtures, and the object of these
lithopone tests at Atlantic City and Pittsburg was to determine whether
satisfactory paints could be made of this pigment for exposure in this
country. Failure of the tests, however, in nearly every case except
where zinc oxide and whiting were mixed with the lithopone, indicated
that pigments such as zinc and whiting are necessary in order to prevent
the decomposition of lithopone pigment paints. The decay of lithopone
paints after they are applied seems to start with rapid oxidation of the
linseed oil, and this oxidation seems to continue in a progressive and
even accelerated way; after six months' exposure the surface of the
paint being chalked to a great extent and showing rapid decomposition of
the binder or vehicle. Inasmuch as lithopone is really an inert pigment,
this rapid decomposition of its vehicle cannot be explained in the same
way as the decomposition of the vehicle of pure white lead paints, where
the alkaline nature of the lead is probably responsible for the
formation of easily destroyed compounds. As complete failure had taken
place in nearly every case where lithopone had been used, it was decided
to condemn the lithopone panels on the fence, consisting of formulas 21
Public-domain text, read in full here on John Shaqi.
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