Paint Technology and TestsGardner, Henry A. (Henry Alfred)
Science
Paint Technology and Tests
Gardner, Henry A. (Henry Alfred)
Paint
to 27, including panels 151 to 164 in white, panels 131 to 144 in
yellow, and 109 to 122 in gray. These lithopone tests were later on
replaced by new tests in 1909, which will be reported upon later in this
book.
=General Results.= From these tests, the inspectors reached the
unanimous conclusion that a paint made from any mixture of more than one
white opaque pigment, either when used alone or in combination with
small percentages of inert pigments, is far superior to any one single
pigment paint. It was found that the straight white lead paints failed
in every case, and this failure was so marked as to make it a conclusive
demonstration of the unfitness of white lead along the Atlantic coast,
when used without other pigments. Paints made with large percentages of
white lead, however, gave excellent results.
Gypsum was found unsafe to use in any large proportion in a paint,
because of its solubility and liability to percolate through the coating
of linoxyn or dried film, thus destroying the surface of the paint.
Whiting, or calcium carbonate, demonstrated that it could be used in
moderate percentage with some efficiency, but it was evident that any
great excess of this pigment must also be avoided on account of its
tendency towards rapid chalking. Magnesium silicate, aluminum silicate,
and silica are three inert pigments which proved to be of great value in
strengthening and reinforcing paints, especially when they were used in
small percentage. In the same way, black fixe and barytes, or barium
sulphate, also appeared to be useful in strengthening a paint. As these
two last named pigments are chemically the same but physically
different, the use of both in a paint formula is considered
advantageous, because of the differences in size and form of their
particles.
=Color Tests.= It was the unanimous conclusion of all the inspectors
that panels of all formulas which were tinted either gray or yellow were
showing far superior wear and less chalking and checking than those
which were painted in plain white. The reinforcing action of the tinting
materials must be credited for this lengthening of the wear of such
paints. Formulas 5, 6, 9, and 16, for instance, in the gray, were in
most excellent condition, and in these formulas were used ochre, umber,
bone-black, carbon-black, Venetian red and other inert bases. On the
yellow panels, formulas 5, 6, 9, and 16 were also in very superior
condition, and in these formulas chrome yellow and inert pigments were
also used.
Some of the color tests included the priming of boards with white lead,
zinc oxide, sublimed white lead, lithopone, and other single pigment
paints. Over these priming coats was placed a high grade brilliant
paranitraniline red. Fairly good results were obtained in every case,
but especially when lithopone or zinc oxide was used as a priming base.
These pigments seemed to have no effect upon the constitution of the
para red.
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