IMPROVEMENTS IN THE MANUFACTURE OF RED PIGMENTS OR PAINTS
Year: 1884

page_text: I JOHN COWDERY MARTIN of Upper Hill Street Richmond in the County of
Surrey Engineer do hereby declare the nature of my Invention for "IMPROVEMENTS
IN THE MANUFACTURE OF RED PIGMENTS OR PAINTS" to be as follows:-
The improvements consist in treating as hereafter described the oxide of lead
known as red lead or a mixture of red and white lead I heat these with a weak
solution of alkali in water and a small quantity of the red colouring matter
hereafter described maintaining the materials of a pasty consistency.
A quantity of acid as the acetic nitric or other suitable acid or of acetate or
nitrate of lead sufficient to neutralise the alkali used is dissolved in water and
added to the lead compound upon which the whole. mass assumes a brilliant
vermillion tint and which I then dry.
The red colouring matter I employ other than that of the red lead or of red lead
acted upon by heat is that known as aniline scarlet.
I sometimes also combine the herin named red or scarlet colouring matter with
white lead alone or with zinc white and sometimes I combine the various materials
in a cold state.
I grind the pigments resulting from the above combinations into paint with oil
in the ordinary manner.
Dated this 20th day of Manal 1001
I JOHN COWDERY MARTIN of 5 Upper Hill Street Richmond in the County of
Surrey do hereby declare the nature of my invention for "IMPROVEMENTS IN THE
MANUFACTURE OF RED PIGMENTS OR PAINTS" and in what manner the same is
to be performed, to be particularly described and ascertained in and by the following
statement:-
The improvements consist in treating as hereafter described, the oxide of lead
known as red lead, or the variety of red oxide of lead known as orange lead, or a
mixture of these with white lead. I treat these with a weak solution of alkali in
water, and a small quantity of the red colouring matter hereafter named, main-
Price 2d1

page_text: taining the materials of a pasty consistency. A quantity of acid as the acetic,
nitric, or other suitable acid, or of acetate or nitrate of lead, sufficient to neutralise
the alkali used, is dissolved in water, and added to the lead compound, upon which
the whole mass assumes a brilliant vermilion tint, and which I then dry. The red
colouring matter I employ.other than that, of the,red lead, or red lead acted upon
by heat, is that known commercially as" aniline scarlet" although chemically this
may not be the correct definition, and I use the deepest and brightest shade of this
colouring matter procurable.
The proportions of the lead oxide, white lead and scarlet colouring matter
described, vary with the tint or shade of colour required.
The quantity.of.alkali-used. (and which I prefer to be carbonate of either soda.or
potash) is from one to two per cent, by weight, of the whole of the other materials,
and sufficient acetic, or nitric acid, or acetate, or nitrate of lead, is used to neutralise,
or become decomposed by the alkali.
The lead oxide, or lead oxide and white lead, I mix with water to the consistency
of a thin paste, placing these in a pan over the fire, and adding the alkali in
solution.
On the application of a moderate heat, the oxide thickens, and assumes a more
or 'less 'hydrated condition, and a partial vermilion tint. I then add the scarlet
. colouring matter, and the acetate or nitrate of lead, to complete the shade of colour
required, and the mass being then of a thick pasty consistency is removed from the
pan, and dried in a stove, in the usual way. The alkali and acid, or the alkali and
soluble lead salt, may, be combined previous to being added to the lead oxide, and
the several materials may also be combined in a cold state, but the body of the
resulting pigment, when used as an oil paint, does, not then appear to be so good,
and I prefer the method first above described as giving the best results. As stated
in my provisional specification,, I grind the pigments resulting from the above com-
.binations into paint with oil-in,the ordinary way. I am aware that, red pigments
termed vermilionettes, are now made by combining the dye, stuff, known as "Eosin,"
with white, lead, and white,zinc, but, the colour of this material is as is well known
extremely fugitive, and the colour of the pigments made with it partake, of, this
character. The colour produced by, the combination of the several materials herin
:named,.does not fade, and resists as an oil paint, long exposure to the atmospheric
influences equally well with genuine vermilion.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed .I declare that what
I claim is
Treating or combining the several materials herin named substantially as
described for the purpose of making red pigments or paints.
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