Paint Technology and TestsGardner, Henry A. (Henry Alfred)
Science
Paint Technology and Tests
Gardner, Henry A. (Henry Alfred)
Paint
[Illustration: CRACKING.--Type of Decay Exhibited by Improperly Made
Paint (magnified view)]
[Illustration: GENERAL DISINTEGRATION.--Type of Decay Exhibited by
Improperly Made Paint (magnified view)]
[Illustration: SCALING.--Type of Decay Exhibited by Improperly Made
Paint (magnified view)]
=Gloss.= The gloss of the various panels was a condition which was also
reported upon, the middle board of each panel being washed with a wet
sponge one day before the inspection so that any surface dirt might be
removed. By looking at a panel from the side, a day after the washing,
the inspector was enabled to get a fair idea of the degree of gloss
exhibited by each formula.
=Hiding Power.= The hiding power of each paint was determined, as before
described, by observing the degree to which the stencilled lampblack
cross on the priming coat was visible through the second and third
coats. Single pigment paints such as white lead possessed very great
hiding power and obscured the black cross almost completely, while the
cross was quite visible through paints containing high percentages of
crystalline pigments.
=Checking.= The checking of each panel was determined by examining with
a small high-power hand glass magnifying fifteen diameters. It is well
known that examinations with such a hand glass will not determine
whether so-called fine matt checking is taking place, but it will
determine whether checking has appeared to any marked extent. Fine matt
checking is the first sign of the decomposition of a paint, and is
preliminary to the visible checking seen by the naked eye, which is
often followed by alligatoring. Examination of some formulas disclosed
this so-called alligatoring and even the exposed wood between the
fissured surface which had developed from what were at first fine hair
checks. It is, in the opinion of the writer, possible to predict with a
fair degree of accuracy by examination of a painted surface, one year
after exposure, how the paint will wear in the future and what its
appearance will be at the end of another year.
=Hardness.= The hardness of each panel could not be determined with any
degree of accuracy, but the inspectors were able to roughly determine
this condition by very close inspection. From practical experience of
the wearing of white lead and zinc oxide, and the comparative hardness
of these two pigments, zinc oxide was selected as the maximum for
hardness and termed number 10, while white lead was selected as the
minimum and termed number 1. The varying degrees of hardness exhibited
by the formulas were recorded in terms from one to ten. This comparison
of course was only an approximate one.
=General Condition.= The so-called general conditions of the panels was,
as a rule, the consensus of the judgment held by the various inspectors,
with due regard to such properties as chalking, checking, gloss, hiding
power, color maintenance, condition of surface, etc.
CHAPTER VIII
RESULTS OF ATLANTIC CITY TESTS
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