AN IMPROVED PROCESS FOR BRONZE COLORING
Year: 1864

page_text: PATENT to Hiram Tucker, of Newton, in the County of Mid-
dlesex, in the State of Massachusetts, one of the United States of
America, for the Invention of "AN IMPROVED PROCESS FOR BRONZE COLORING
er, or Newton,
the County of Mid-
dlesex, in the State of Massachusetts, one of the United States of
America, for the Invention of "AN IMPROVED PROCESS FOR BRONZE COLORING
IRON."
Sealed the 3rd March 1865, and dated the 11th October 1864.
PROVISIONAL SPECIFICATION left by the said Hiram Tucker at the
Office of the Commissioners of Patents, with his Petition, on the 11th
October 1864..
I, HIRAM, TUCKER, of Newton; in the County of Middlesex, in the State of
Massachusetts, one of the United States of America, do, hereby declare the
nature of the said Invention for "AN IMPROVED PROCESS FOR BRONZE COLORING
IRON," to be as follows:
My Invention consists in a novel process by which I produce on the surface
of iron a change of color, which I term bronzing, not by the application of
pigments in the forms of solutions, paints, or lacquers, whether dried or hardened
by heat or by simple atmospheric exposure, but by chemical changes of and
upon the surface of the iron.
I produce the bronze effect or color by the combined action of heat and
linseed oil, or its equivalent, upon the surface of the metal. Heat alone
produces that change of color on the brightened surface of iron, which ranges
from light straw color to deep blue, which change I understand to be the
result of oxidation (though it may be the result of some other chemical
superficial change of the iron, the chemistry of which is not understood by me),
and the oil acting upon or with the resultant of heat on the iron changes the

page_text: color produced on the iron by heat alone to a bronze tint, the darkness of
which depends upon the intensity of the heat to which the iron is submitted,
and also upon the number of times the operation is repeated.
The surface of the iron is cleaned from sand, scale, or other foreign matter,
and where fine effects are desired, the surface is best made smooth or polished.
Under given conditions of heating and oiling, the finer the polish the lighter
is the bronze tint produced. In cases where ornamentation is obtained by
relief, the salient parts-should be-the-most-highly-polished- or-most smoothly
surfaced, in order that the color produced upon them shall not be so deep as it
is on those parts which are in the rear, so as to imitate thereby more nearly the
effect of genuine bronze, in which its natural oxidation is apt to be somewhat
worn away from its salient parts, which are therefore lightest in color. When
the iron is thus prepared,. I cover it with a very thin coating of linseed oil,.or
its equivalent, and rub off the superfluous oil with a dry rag or sponge, or
otherwise. Next I submit it to a degree of heat which will change a
brightened surface of clean unoiled iron to a color varying from a light straw
color to a deep blue, the lowest degree of heat producing the lightest colored
changes and the lightest bronze, and the highest degree of lieat producing the
darkest colored changes and the darkest_bronze.; but as the oil is present
the metal does not change its color under the influence of heat, as it would if
free from the oil. As the, iron becomes heated, the color. obtained will be
bronze of a darkness, corresponding to the degree of heat employed; but it
should be observed that the heat may be made so intense, and may be so long
continued as to destroy the effects of the oil, in which case the iron will lose
the bronze tint acquired, and will, assume the dark blue shade. Th
The perfection
of the results obtained under these instructions will of course depend
considerable degree upon the dexterity and watchfulness of the operator.
When the desired shade of bronzing is obtained, the, iron is removed from
the oven or furnace, and if desired may again be treated with oil as
even if not cool, and then again submitted to the action of heat, as described,
and the operation of oiling, and heating may be repeated indefinitely, each
repetition deepening the shade of the bronzing. I recommend that, at each
repetition the degree of heat should be less than the degree immediately before
employed; the process may be carried to such an extent by repetition of oiling
and heating as to produce. .a very dark, color, black even may be thus
produced.
1:
**
11:
a
before,
The particular process above described is the best known to me, but it may
be modified somewhat in practice without departure from my Invention, as
for instance, the iron may first be heated and afterwards oiled, the oiling

page_text: with the heat contained in the iron changing the color obtained by heat alone
into a bronze. The bronzing may be protected by a coat of varnish (that
which is colorless being preferred) and the varnish may be dried over the
bronzing by exposure to the atmosphere, or it may be baked or dried by heat,
and if desired the bronze color may be darkened by submitting the varnish to
a degree of heat sufficient to deepen and change its hue.
SPECIFICATION in pursuance of the conditions of the Letters Patent; filed
by the said Hiram Tucker in the Great Seal Patent Office on the
18th March 1865.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HIRAM
TUCKER, of Newton, in the County of Middlesex, in the State of Massachusetts,
one of the United States of America, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eleventh day of October, in the year of our Lord
One thousand eight hundred and sixty-four, in the twenty-seventh year
of Her 'reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Hiram Tucker, Her special licence that I, the said Hiram
Tucker, my executors, administrators, and assigns, or such others as I,
the said Hiram Tucker, my executors, administrators," and assigns, should at
any time agree with; and 'no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully might
make, use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland; the Channel Islands, and Isle of Man, an Invention for
"AN IMPROVED PROCESS FOR BRONZE COLORING IRON," upon the condition, amongst
others, that I, the said Hiram Tucker, my executors or administrators, by
an instrument in writing under my, or their, or one of their hands and
seals, should particularly describe and ascertain the nature of the said
Invention, and in what manuer the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Hiram Tucker, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, that is to say:-".

page_text: My Invention consists in a novel mode or process by which I produce on
the surface of iron a change of color, which I term bronzing, not by the
application of pigments in the forms of solutions, paints, or lacquers, whether
dried or
hardened by heat or by simple atmospheric exposure, but by chemical
changes of and upon the surface of the iron.
13.
In the practice of my Invention I produce the bronze effect, or color by the
combined action of heat and linseed oil or its equivalent upon the surface of
the metal. Heat alone produces that change of color on the brightened
surface, of iron, which ranges from light straw color to deep blue, which I
understand to be the result of oxidation (though this color may be the result
of some other chemical superficial change of the iron, the chemistry of which
may not be understood by me), and the oil acting upon or with the resultant
of heat, or in conjunction with heat on the iron, changes the color thereby
produced to a bronze tint, the darkness of which depends upon the intensity
of the heat to which the iron is submitted, and also upon t
the number of times
the operation is repeated.
街
2.
3: ..
i
B
In practice I proceed as follows:-The surface of the iron is cleaned from
sand, scale, or other foreign matter, and where, fine effects are desired the
surface is best made smooth or polished. Under given conditions of heating,
and oiling, the finer the polish the lighter is the bronze., tint produced. In
cases
where ornamentation is obtained by relief, the salient parts-should be
the most highly polished or most smoothly, surfaced, in order that the color
produced upon them shall not be so deep as it is on those parts which, are in
the rear,
so as to imitate thereby more nearly the effect of genuine, bronze, in
which it's. natural oxidation is apt to be somewhat worn away from its salient
parts, and is therefore lighter in color at such parts. When the iron is thus
prepared, I cover it with a thin coating of linseed oil or its equivalent, (such
a coating as I. find best attained by rubbing off the oiled,surface with a sponge
or otherwise) and then submit it to a degree of heat which will change
brightened surface of clean unoiled iron to a color varying from a light straw
color to a deep blue, the lowest degree of heat producing the lightest colored
changes and the lightest bronze, and the highest degree of heat producing the
darkest colored changes and the darkest bronze; but as the oil is, present, the
metal does not change its color under the, influence of heat as it would if free
213
25
'a.
the oil. As the iron becomes-heated the color obtained will be bronze of
an intensity corresponding, to, the degree of heat employed; but it should
be observed that the heat may be made so intense and so long continued as to
destroy the effects of the oil, in which case the iron will lose the bronze tint;
acquired, and will assume the dark blue shade. The perfection of the results,

page_text: obtained under these instructions will of course depend in a considerable
degree upon the dexterity and watchfulness of the operator.
In practice I prefer to use boiled linseed oil or raw linseed oil. When the
oil is boiled before application the coating of it which is applied should be
wiped off so as to leave but very little indeed of the oil in order to produce the
best results; but when raw oil is used, a good result follows if the work is
first gone over with a full brush, and the excess of oil afterward taken off with
a dry brush. When the desired shade of bronzing is obtained, the iron is
removed from the oven or furnace, and if desired may again be treated with
oil as before, even if not cool, and then again submitted to the action of heat
as described, and the operation of oiling and heating may be repeated in-
definitely, each repetition deepening the shade of the bronzing. I recommend
that at each repetition the degree of heat should be less than the degree
immediately before employed. The process may be carried to such an extent
by repetition of oiling and heating as to produce a very dark color, black even
may be thus produced.
The particular process above described is the best known to me, but it may
be modified somewhat in practice, without departure from my Invention, as
for instance :-The iron may first be heated and afterwards oiled, the oiling
with the beat contained in the iron changing the color obtained by heat alone
into a bronze. The bronzing may be protected by a coat of varnish (that
which is colorless being preferred) and the varnish may be dried over the
bronzing by exposure to the atmosphere, or it may be baked or dried by heat,
and if desired the bronze color may be darkened by submitting the varnish to
a degree of heat sufficient to deepen and change its hue.
HIRAM TUCKER. (L.S.)