The Washington times., 1923-09-15
RED LEAD SAVES
STEEL FROM
RUST
Structural Work Should Have
at Least Two Coats, Says
Writer in Building Age.

Structural steel may come to the
Job with or without the printing
coat of paint, says A. Ashmun
Kelley in The Building Age.
The practice at one time was uni
formly to coat it, but this was
found in most cases to be wrong,
as the scale would loosen and re-
move the paint, besides which the
paint was usually applied by care
less, unskilled workmen, and had
to be removed.
BY allowing the implanted metal
to remain uncoated for some time
before erection the weather caused
much OF the scale and dirt to fall
of, and when It was time to coat
It the metal was cleaned with steel
brushes and then it received the
paint properly.
This printing coat is usually APP
piled just before assembling the
parts. The best coating Is red lead
thinned out with hnseed oil. the
paint to be mixed fresh each day,
as it win stiffen or harden IL left
too long after mixing, say over
night. It is possible to mix as
much as thirty-three pounds of dry
red lead with a gallon Of oil, this
making good workable paint, for
the coating should not be mere
film. A proper mix Of red lead
gives q hard and yet elastic coat.
ing, one that IL thick and yet viii
not crack. It fills the pores OF
the metal and adheres well to 1t.
Red lead prevents rusting. and
water cannot penetrate It. This is
why marine underwriters favor IL,
and why the hulls OF vessels are
PINNED with it, as also the locks
on the Panama Canal. In short,
practically all structural work is
protected with red lead paint.
Steel structural work should
paint, and each coat, no matter how
many, should be slightly colored,
In varying degrees, so that the In
spector may readily detect faulty
work. A little lampblack with the
red lead will do for the purpose,
and this black IL itself q useful
addition in securing a uniformity
OF the thickness Of the film.
To secure the best results the
structural steel should be made
perfectly clean Of all matter that
can be removed, such as moisture.
grease, scale, etc. The time given
to this work is time profitably
spent. Then, all small pinholes,
cracks, assures between plates,
poles, ETC., should be filled be-
fore applying the paint. In no
case should two parts of bare
metal meet. as that sets up local
galvanic action. which leads to
corrosion. Paint therefore every
part Of the whole surface. White
lead, carbonate of the metal
lead, ana at one stage Of its man.
ufacture an oxide, should not bc.
used for printing iron or steel. nor
should oxide Of zinc paint, as It.
also Is capable Of eating into the
metal. All the iron ore paints
contain phosphoros and sulphur,
and these substances are Injurious
to iron or steel. Burning, how.
ever, removes these inimical prop
critics Of the ore.
Asphaltum does not make a good
coating, though 1t Is sometimes
employed on bridge steel construc.
ton. 1t 10 usually thinned out
with benzine, which evaporates and
leaves the painted surface rough
and In Q condition to catch the
SCOT and dirt, which rain and
other forms Of moisture act upon
to form acid that acts upon the
metal and brings rusting.
Old painted iron work should be
cleaned by scraping and burning off,
ana then be given a coat of tur-
penttne or benzine. after which it
may be painted.