Improvements in the Manufacture of Pigments or Paints.
Year: 1891

page_text: Date of Application, 23rd July, 1891
Complete Specification Left, 22nd Apr., 1892-Accepted, 23rd July, 1892
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Pigments or Paints.
I JOHN COWDERY MARTIN of the Lead and Zinc White Works Chatham
Street Grosvenor Street Camberwell London Manufacturer do hereby declare the
nature of this invention to be as follows:-
My invention consists in treating or operating upon pigments of which zine
oxide or zinc sulphide form a part also upon the white lead produced by any of the
precipitation or wet processes of manufacture and as these pigments are generally
of inferior specific gravity and body and require an excess of oil for conversion
into paint, causing them to condense and assume the paste like condition of ground
white lead with a moderate quantity of oil. I take the pigment in the form of a
dry powder and place it in a horizontal pug mill or other suitable mixing apparatus
and add as much water as when intimately mixed will produce a slightly damp
powder or the degree of dampness may be produced in any other convenient manner.
I submit the damp powder to the action of edge runners or other suitable crushing
machinery until the bulk is considerably reduced and the specific gravity increased.
It is then dried and treated in the same manner in a similar apparatus oil being
substituted for the water previously used and in such quantity as will cause it to
remain in a perfectly powder like condition in the mixer above described but will
cause it to slightly adhere together when the crushing is completed under the edge
runners.
It is then transferred to the ordinary pug mills and as much oil added as will
bring it to a paste like condition after which it is ground in the usual manner.
Dated this 22nd day of July 1891.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Pigments or Paints.
I, JOHN COWDERY MARTIN, of the Lead and Zinc White Works, Chatham
Street, Grosvenor Street, Camberwell, in the County of Surrey, Manufacturer, do
hereby declare the nature of my said invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement :-
Pigments, of which zinc oxide or zinc sulphide forms a part, and white lead
produced by any of the precipitation or wet processes of manufacture, are generally
of inferior body and specific gravity and require an excess of oil for conversion
into paint. My invention relates to methods of treating or operating upon such
materials by what I term my improved preparing process in such a manner as to
cause them to be condensed and assume the paste-like condition of what is known
in the trade as ground white lead (that is white lead ground in oil) when mixed
with a moderate quantity of oil.
I take the material of the pigment in the form of a dry powder, and place it in a
horizontal pug-mill or other suitable mixing apparatus, and add as much water as,
when intimately mixed, will produce a slightly damp powder, or when the pigment
is produced by a wet process the material may be taken before it is quite dry, or
the degree of dampness of the powder may be produced in any other convenient
manner. I submit the powder in the required damp condition to the action of
edge runners or other suitable crushing machinery until the bulk is considerably
reduced and the specific gravity increased. The partially prepared material is then

page_text: dried and treated in a similar apparatus by mixing it with such a quantity of oil as
will cause it to remain in a powder-like condition in the mixer above described but
will cause it to slightly adhere together when the crushing is completed under edge
runners. It is then transferred to the ordinary pug mills, and as much oil added
as will bring it to a paste-like condition, after which it is ground into paint in the
usual manner.
The quantity of oil required to reduce the pigments treated in accordance with
my improved preparing process, to the stiff paste-like condition corresponding to
that in which ground white lead is usually sold, varies according to circumstances,
but as a rule precipitated white lead, which often requires an excessive quantity of
oil and is too bulky to be contained in kegs of the regulation sizes, can, by sub-
jecting it to the process above described, be made into a paste of the required
consistency with about the same quantity of oil as white lead made by what is
known as the stack process, and a given weight can be contained in packages of no
larger size than are required for stack lead, although I find that the best results
are obtained by crushing the damp materials first with water and subsequently with
oil. I would have it noted that in some cases the crushing with water may be
omitted and that the important feature in my invention is the process of grinding
with oil as herein before directed.
When zinc oxide alone is treated with oil in the usual way, it becomes so
tenacious as to require great power to grind it, and it is more easily treated when
combined with baryta or some other substance; but I have found that when
pigments composed largely of zinc oxide are treated, under favourable circumstances,
in the manner above described, they grind well with as little as 8 lbs. of oil
per 112 lbs. of pigment, but under less favourable circumstances somewhat more
oil is required. Generally when treating zinc compounds by my preparing process
I do not find it necessary to crush with water but I add, in the preparatory crushing
with oil as above described, about two thirds of the whole quantity of oil required
and after so treating it in a damped state I add the required additional quantity of
oil in the pug mills just before the final grinding operation. The same proportions
may be used with refractory white lead, but as I have found the result is sometimes
influenced by slight differences in the quality of the oil, and sometimes even by the
condition of the atmosphere, the exact quantity or proportion of oil to be mixed at
each stage of the operation is best determined by experience, as will be well
understood but care must always be taken to keep the pigment as a damp powder
in the preparatory grinding or crushing process and to allow the edge runners to
operate sufficiently upon it while in that damp powdery state.
As above stated the best effect is produced by my preparing process when the
pigment is first damped with water and crushed in that state and when after being
dried or deprived of superfluous water the material is further treated by damping
or mixing it with a small dose of oil and again crushing the material, but I have
found that good results can be obtained by omitting the damping with water and
crushing in that state and by using the damping and crushing with oil only as a
preparing process.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I would have it understood
that I do not separately claim operating upon dry powders under edge runners or
other suitable crushing machinery, or upon pigments containing sufficient oil or
moisture to at once form a paste, but that what I do claim is :-
First In the manufacture of pigments or paints the use of the preparing process
by crushing the dry powdered material under treatment with a sufficient quantity
of water and subsequently crushing with oil in the manner hereinbefore described
and for the purpose specified.
Second-In the manufacture of pigments or paints the use of my preparing
process for effecting the condensation of the material so as to increase its specific
gravity and enable it to be ground into paint with a comparatively small quantity

page_text: of oil, by first crushing the said material by means of edge runners, or other suitable
crushing machinery, while such material is in the form of a powder slightly damped
with oil and then treating the prepared material in the pug mill as hereinbefore
described.
Third-The improved pigments or paints manufactured by my improved
preparing process as above described.
Dated this 14th day of April 1892.
J. C. MARTIN,
Per W. H. Beck,
115, Cannon Street, London, E.C., Agent.