IMPROVEMENTS IN THE MANUFACTURE OF CERTAIN PIGMENTS OR PAINTS.
Year: 1870

page_text: LETTERS PATENT to Bristow Hunt, of No. 1, Serle Street, Lincoln's
-
Inn, in the County of Middlesex, Gentleman, for the Invention of
"IMPROVEMENTS IN THE MANUFACTURE OF CERTAIN PIGMENTS OR PAINTS.".
A communication from abroad by Marc Antoine François Mennons,
Office of the Commissioners of Patents, with his Petition, on the
17th May 1870.
I, BRISTOW HUNT, of No. 1, Serle Street, Lincoln's Inn, in the
3 County of Middlesex, Gentleman, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN THE MANUFACTURE OF CERTAIN PIGMENTS
OR PAINTS," (a communication to me from abroad by Marc Antoine
I, BRISTOW HUNT, of No. 1, Serle Street, Lincoln's Inn, in the
3 County of Middlesex, Gentleman, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN THE MANUFACTURE OF CERTAIN PIGMENTS
OR PAINTS," (a communication to me from abroad by Marc Antoine

page_text: François Mennons, of Paris, in the Empire of France,) to be as
follows:-
The universal use of lead paint proves that up to the present time no
substitute has been found to equal it in covering and durable properties,
but the scrious injury it causes to the health of those engaged in its
manufacture and use has made it very desirable to find some substance
or compound by admixture of which the objectionable qualities of the
lead might be counteracted without deteriorating its value as a pigment.
Various ingredients have already been used for this purpose, and while
cheapening the cost of the product have to a certain extent aided
in neutralising its deleterious effects when applied to, house painting.
The usual admixture is with barytes, which though cheapening the cost
impoverish the paint, and to find a metal which shall combine with the
lead and be of equal density, or nearly so, has hitherto been vainly
attempted. Oxide of zinc has up to the present time been tried without
success, its extreme lightness causing it to separate from the lead when
mixed as paint, the lead sinking to the bottom while the zinc remains
on the surface.
The object of this Invention is so to prepare the constituents of the
compound paint that all shall be of equal density or body, or nearly so,
and become inseparably intermixed when ground in oil.
The recent discovery of a minc in America yielding an ore (called
"Bartlett lead") which contains a large per-centage of zinc and lead
in natural combination has led to experiments with a view to its
adaptation as a pigment, and also to further experiments in mixing
artificially lead and zine in any desired proportions for the production of
a pigment that shall combine with the excellent qualities of lead the
superior qualities of zinc, forming a paint that shall supersede the white
lead alone. The paint thus obtained from either the natural or artificial
combination possesses greater covering properties than lead, it resists
the action of sulphuretted hydrogen and other destructive gases, is
cheaper, more durable, and can be used without injury to the health. It
may also be remarked that the mixture of zinc with the lead besides
giving greater smoothness to the paint greatly improves the colour, and
in every respect this combination offers advantages over the white lead
used alone.
i

page_text: To overcome the difficulty above stated of producing an oxide of zinc
that shall have the same density as carbonate of lead and its usual
adulterations or admixtures I have found it necessary to prepare the
oxide of zinc by submitting it to a process of rolling under heavy edge
runners or metal rolls, the former being preferred as more effectually and
uniformly crushing the particles of the oxide and reducing its bulk,
which in the natural or uncompressed state is from three to four times
that of white lead, weight for weight. This process effectually accom-
plishes the object in view, a fresh surface of oxide being constantly
presented by the usual scraper or follower to the grinding and crushing
action of the revolving stones or rolls. The product of this operation is
turned out as a powder and requires no further manipulation before
mixing with other ingredients as described herein. The densified zinc
thus obtained is amalgamated with the ordinary carbonate of lead or
precipitated lead of commerce in such proportions as may be desired by
passing the two together through a fine sieve or by any other convenient
method with or without the admixture of other ingredients, so that the
whole shall be thoroughly incorporated before passing to the mixing tub
preparatory to grinding with oil in the usual manner. The pigment thus
produced will be found to be of uniform density throughout like white
lead. For oxide of zinc paint I use the oxide of zinc densified in the
same manner where opacity or covering properties are required equal
or approximating to those of lead, and if any admixture of less density
be required for use I grind or roll the whole together or incorporate the
ingredients by sieving after grinding them separately. The paint thus
produced is of greater commercial value than white lead for common
purposes and far superior where great smoothness and durability is
required, and having no lead in its composition it is unaffected by
sulphuretted hydrogen and other injurious gases. For the paint made of
"Bartlett lead" and other analogous natural products I use the material
densified or undensified, and with or without the addition of oxide of
zinc, carbonate of lead, barytes, or other ingredients as may be required,
the mixing, when necessary, being effected by sieving or otherwise, as
above described.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Bristow Hunt in the Great Seal Patent Office on
the 15th September 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, BRISTOW
HUNT, of No. 1, Serle Street, Lincoln's Inn, in the County of Middlesex,
Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Seventeenth day of May, in the year
of our Lord One thousand eight hundred and seventy, in the thirty-
third year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Bristow Hunt, Her special licence
that I, the said Bristow Hunt, my executors, administrators, and
assigns, or such others as I, the said Bristow Hunt, 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 "IMPROVEMENTS
IN THE MANUFACTURE OF CERTAIN PIGMENTS OR PAINTS," (a communication to
me from abroad by Marc Antoine François Mennons, of Paris, in the
Empire of France,) upon the condition (amongst others) that I, the said
Bristow Hunt, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and scals, should
particularly describe and ascertain the nature of the said Invention, and
in what manner 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 Bristow Hunt, do hereby declaro
the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement, that is to say :-
The universal use of lead paint proves that up to the present time no
substitute has been found to equal it in covering and durable properties,
but the serious injury it causes to the health of those engaged in
its manufacture and use has made it very desirable to find some sub-

page_text: stance or compound by admixture of which the objectionable qualities
of the lead might be counteracted without deteriorating its value as a
pigment. Various ingredients have already been used for this purpose
and while cheapening the cost of the product have to a certain extent
aided in neutralising its deleterious effects when applied to house painting.
The usual admixture is with barytes, which though cheapening the
cost impoverishes the paint, and to find a metal which shall combine
with the lead and be of equal density or nearly so has hitherto been
vainly attempted. Oxide of zinc has up to the present time been tried
without success, its extreme lightness causing it to separate from the
lead when mixed as paint, the lead sinking to the bottom while the zinc
remains on the surface.
The object of this Invention is so to prepare the constituents of the
compound paint that all shall be of equal density or body, or nearly so,
and become inseparably intermixed when ground in oil.
The recent discovery of a mine in America yielding an ore (called
"Bartlett lead") which contains a large per centage of zinc and lead
in natural combination has led to experiments with a view to its
adaptation as a pigment, and also to further experiments in mixing
artificially lead and zinc in any desired proportions for the production
of a pigment that shall combine, with, the excellent qualities of lead
the superior qualities of zinc, forming a paint that shall, supersede the
white lead alone. The paint thus obtained from either the natural or
artificial combination possesses greater covering properties than lead,
it resists the action of sulphuretted hydrogen and other destructive
gases, is cheaper, more durable, and can be used without injury to the
health. It may also be remarked that the mixture of zinc with the
lead besides giving greater smoothness to the paint greatly improves the
colour, and in every respect this combination offers advantages over
the white lead used alone.
To overcome the difficulty above stated of producing an oxide of zinc
that shall have the same density as carbonate of lead and its usual
adulterations or admixtures, I have found it necessary to prepare the
oxide of zinc by submitting it to a process of rolling under heavy edge
runners or metal rolls, the former being preferred as more effectually
and uniformly crushing the particles of the oxide and reducing its bulk,
which in the natural or uncompressed state is from three to four times

page_text: that of white lead, weight for weight. This process effectually accom-
plishes the object in view, a fresh surface of oxide being constantly
presented by the usual scraper or follower to the grinding and crushing
action of the revolving stones or rolls. The product of this operation
is turned out as a powder, and requires no further manipulation before
mixing with the other ingredients as described hercin. The densified
zinc thus obtained is amalgamated with the ordinary carbonate of lead
or precipitated lead of commerce in such proportions as may be desired
by passing the two together through a fine sieve or by any other con-
venient method, with or without the admixture of other ingredients, so
that the whole shall be thoroughly incorporated before passing to the
mixing tub preparatory to grinding with oil in the usual manner. The
pigment thus produced will be found to be of uniform density throughout
like white lead. For oxide of zinc paint I use the oxide densified in the
same manner, where opacity and covering properties are required equal
or approximating to those of lead, and if any admixture of less density be
required for use, I grind or roll the whole together, or incorporate the
ingredients by sieving after grinding them separately. The paint thus
produced is of greater commercial value than white lead for common
purposes and far superior where great smoothness and durability are
required, and having no lead in its composition it is unaffected by
sulphuretted hydrogen and other injurious gases. For the paint made of
"Bartlett lead," and other analogous natural products I use the material
densified or undensified and with or without the addition of oxide of
zinc, carbonate of lead, barytes, or other ingredients as may be required,
the mixing when necessary being effected by sieving or otherwise as
above described.
Having now described the nature of the said Invention, and the
manner of carrying it into effect, I declare that what I claim and desire
to protect by Letters Patent, is—
Firstly. An improved pigment composed of the product called
"Bartlett lead" or other similar products containing lead and zinc in
natural combination employed either in the densified or undensified state,
as above set forth.
Secondly. The combination of the said Bartlett lead with oxide;
of zinc, ordinary carbonate of lead, barytes, and other ingredients or
any of them as desired, the said ingredients being brought to a uniform

page_text: degree of density or nearly so, and afterwards intermixed by sieving or
otherwise, as above set forth.
Thirdly. The improved mode of densifying either together or separately
the constituents of pigments by a rolling process, as herein set forth.
In witness whereof, I, the said Bristow Hunt, have hereto set my
hand and seal, this Fourteenth day of September, in the year of
our Lord One thousand eight hundred and seventy.