IMPROVEMENTS IN PROCESSES FOR PRESERVING, STRENGTHENING, AND OTHERWISE IMPROVING PLASTER CASTS, MOULDS, NATURAL AND ARTIFICIAL STONES, PART OF SUCH IMPROVEMENTS BEING APPLICABLE FOR FORMING CEMENT OR PLASTER SURFACES ESPECIALLY ADAPTED FOR WALL PAINTING
Year: 1879

page_text: LETTERS PATENT to Martin Westmacott and Charles John Perceval, both of
No. 34, Parliament Street Westminster, for the Invention of "IMPROVEMENTS
IN PROCESSES FOR PRESERVING, STRENGTHENING, AND OTHERWISE IMPROVING
PLASTER CASTS, MOULDS, NATURAL AND ARTIFICIAL STONES, PART OF SUCH
IMPROVEMENTS BEING APPLICABLE FOR FORMING CEMENT OR PLASTER SURFACES
ESPECIALLY ADAPTED FOR WALL PAINTING"
PROVISIONAL SPECIFICATION left by the said Martin Westmacott and
Charles John Perceval, at the Office of the Commissioners of Patents on the
17th September 1879.
«
MARTIN WESTMACOTT and CHARLES JOHN PERCEVAL, both of No. 34, Parliament)
Street, Westminster. IMPROVEMENTS IN PROCESSES FOR PRESERVING, STRENGTH-
ENING, AND OTHERWISE IMPROVING PLASTER CASTS, MOULDS, NATURAL AND
ARTIFICIAL STONES, PART OF SUCH IMPROVEMENTS BEING APPLICABLE FOR
FORMING CEMENT OR PLASTER SURFACES, ESPECIALLY ADAPTED FOR WALL
PAINTING."
:
I
The object of our Invention is clearly set forth in the title as, improvements in
the means or processes to be used for the purpose of preserving, strengthening, and
otherwise materially improving plaster casts; moulds, and natural and artificial.
stones, and in forming cement or plaster surfaces, which shall be especially adapted:
for mural or wall painting; the cement or plaster to be treated also by the strength-
ening or preservative process or processes..
Our Invention consists as follows:-
"
I. Firstly, we use a setting or surface hardening process," which may be thus
described. (We apply this to casts, moulds, or wall cements, which are composed
solely or principally of sulphate of lime or plaster of Paris.) Such articles when
quite dry, are subjected, when their size and form will admit of such treatment, to
immersion, for a space of time varying according to their porosity, of from a few
seconds to one minute, in a solution of the following substances, in or about the
following proportions:-Of sulphate of baryta half a pound, and of bi-borate of soda
CD79

page_text: half a pound, to which is added a gallon of boiling water. In adding more water
the bi-borate of soda need only be used therewith, as the baryta being but slightly
soluable seldom requires to be added. The above solution can be used cold, but
where we require a greater degree of hardness we use twelve ounces of the bi-borate
of soda to the gallon of water which must be used as a warm solution. In some
cases we may prefer to use a solution of bi-borate of soda only, we then desiccate
the articles treated with the solution by artificial heat. In the case of wall
cements the solution must be applied with a brush.
IL The artieles treated as above are next subjected to the second process, which
is termed the "sealing process," when it is repuired that their pores be filled up.
In this, either by immersion or by a brush, a solution of bleached shellac dissolved
in methylated spirits, known in trade as "methylated polish" is applied. Instead
of using this in its thick condition as a polish, we let it settle and apply only the
clear solution, and in such quantity only as will sink into the work, leaving nothing
on the surface. No further drying is required, and the object or material thus
treated is finished if required only for internal purposes. For work intended to be
subjected to atmospheric influence in the open air, in the second or "sealing"
process we use, instead of a solution of clear lac polish, one composed of the finest
pale copal varnish with which has been intimately mixed in a water bath three or
four times its bulk of the finest spirits of turpentine. The object we immerse in
this solution one to two, three or four hours, according to its size or thickness. We
then place the same in a drying room until the spirit is evaporated, by which it is
fitted for the third process.
It
III. The third process we term the "permeating" process. For this purpose we
melt in a water bath the purest mineral wax, for instance pure paraffin, and subject
the object to the same by immersion until it thoroughly permeats the mass.
must be particularly observed that on no account is stearine to be used, as it will
give to the work treated therewith a bad colour. When cold the object or material
is fit or suitable for open air decoration.
IV. The above processes fulfill the requirements of fine art, namely, that no
body must be upon the surface of the object, but in many cases such as large figures
and stone work, where a thin body is not objectionable, we stipple on with a brush
(either before or after the first or second process, or in some cases in lieu of the first
process) one or two coats of the following solution, namely: we take a solution of
silicate of potash and mix intimately with it a small portion of oil, by preference
such an oil as oil of resin, the quantity varying with the amount of free potash in
the solution, also a small quantity of finely powdered white glass where a closer
appearance of statuary marble is required. This solution when dry is free from the
brittleness of ordinary silicate of potash.
V. Our Invention consists further in an improved cement for resisting the
chemical influences of an impure atmosphere, for which purpose we use in or about
the following proportions: sulphate of lime (plaster of Paris) one part by bulk, and
sulphate of baryta from one to one and a half parts. The cement thus composed is
especially adapted for walls for painting in fresco or otherwise, and this cement we
treat according to the process or processes hereinabove described. For cements,
natural and artificial stones, marbles otherwise than sulphate of lime, we omit the
first process.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Martin Westmacott and Charles John Perceval in the Great Seal
Patent Office on the 17th March 1880.
MARTIN WESTMACOTT and CHARLES JOHN PERCEVAL, both of No. 34, Parliament
Street, Westminster. "IMPROVEMENTS IN PROCESSES FOR PRESERVING, STRENGTH-
ENING, AND OTHERWISE IMPROVING PLASTER CASTS, MOULDS, NATURAL AND
ARTIFICIAL STONES, PART OF SUCH IMPROVEMENTS BEING APPLICABLE FOR
FORMING CEMENT OR PLASTER SURFACES, ESPECIALLY ADAPTED FOR WALL
PAINTING."
The object of our Invention is clearly set forth in the title, improvements in
means or processes to be used for the purpose of preserving, strengthening, and
otherwise improving materially plaster casts, moulds, natural and artificial stones,
and in forming cement or plaster surfaces which shall be especially adapted for
mural or wall paintings, the cement or plaster also to be treated by the strength-
ening or preservative process or processes.
Our Invention consists as follows:-
I. Firstly, we use a "setting or surface hardening process," which may be thus
described, and we apply this to casts, moulds, or wall cements, which are composed
solely or principally of sulphate of lime or plaster of Paris. Such articles we subject
when their size and form will admit of such treatment, the material being quite
dry, to immersion for a space of time, varying according to their porosity, of from a
few seconds to one minute, in a solution of the following substances in or about the
following proportions:-of sulphate of baryta half a pound, and of biborate of soda
half a pound, to which is added a gallon of boiling water. In adding more water
the biborate of soda only need be used therewith, as the baryta being but slightly
soluble seldom requires to be added. The above solution can be used cold, but
when we require a greater degree of hardness, we use twelve ounces of the biborate
of soda to the gallon or water, which must be used as a warm solution.
In some
cases we may prefer to use a solution of biborate of soda only. We then desiccate
the articles treated with the solution by artificial heat, the temperature may range
from seventy degrees to one hundred and forty degrees Fahrenheit. When the
solution is used cold, the time of immersion may be lengthened with advantage up
to three minutes. The solution may be applied with a brush.
II. The articles treated are next subjected to the second process, which we term
the "sealing process," which is used when it is required that the pores be filled up.
In the process either by immersion or a brush, a solution of bleached shell-lac,
dissolved in methylated spirits, known in the trade as methylated polish, is applied.
Instead of using this in thick condition as a polish, we let it settle and apply only
the clear solution, and in such a quantity only as will sink into the work, leaving
nothing on the surface. No further drying is required, and the object or material
thus treated is finished if required only for internal purposes.
For work intended
to be subjected to atmospheric influence in the open air, in the second or sealing
process we in some cases use, instead of a solution of clear lac polish, one composed
of the finest pale copal varnish, with which has been intimately mixed in a water
bath about three or four times its bulk of the finest spirits of turpentine. The
object we immerse in this solution, one, to two or three hours, according to its
porosity or thickness. We then place the same in a drying room until the spirit is
evaporated, by which it is fitted for the third process.
III. The third process we term the "permeating process." For this purpose we
melt in a water bath the purest mineral wax, for instance pure paraffin, and subject
the object to the same by immersion until it thoroughly permeates through the
mass. It must be particularly observed that on no account is stearine to be used,
as it will give the work treated therewith a bad colour. When cold, the object or
material is fit or suitable for the purpose of open air decoration,

page_text: The above processes fulfil the requirements of fine art, namely, that no "body"
must be on the surface of the object, but in many cases, such as large figures, stone-
work, etcetera, where a thin body is not objectionable, we stipple on with a brush,
either before or after the first or second processes, in some cases in lieu of the first
process, one or two coats of the following solution, namely:-We take a solution of
silicate of potash and mix intimately with it a small portion of oil, by preference
such an oil as oil of resin or a small quantity of oil varnish, the quantity varying
with the amount of free potash in the solution, also a small quantity of finely
powdered white glass, where a closer appearance of statuary marble is required.
This solution when dry is free from the brittleness of ordinary silicate of potash.
IV. Our Invention consists further in an improved cement for resisting the
chemical influences of an impure atmosphere, for which purpose we use, in or about
the following proportions:-Sulphate of lime (plaster of Paris) one part by bulk, and
sulphate of baryta from one to one and a half parts. The cement thus composed is
especially adapted for walls for painting in fresco or otherwise, and the cement
we treat according to the process or processes hereinabove described. For cements,
stones, (natural and artificial) and marbles, otherwise than sulphate of lime, we
omit the first process.
Having now particularly described and ascertained the nature of our said
Invention, and the manner in which the same is to be performed, we wish it to be
distinctly understood that what we claim and desire to secure by the hereinbefore
in part recited Letters Patent is, the means or processes for preserving, strengthening,
and otherwise improving plaster casts, moulds, natural and artificial stones,
and the formation treatment and utilisation of cement, all as described in. the
Specification.
In witness whereof, we, the said Martin Westmacott and Charles John
Perceval, have hereunto set our hands and seals, this Tenth day of
February, in the year of our Lord One thousand eight hundred and
eighty.
Witness to the signatures of the
'
said Martin Westmacott &
Charles John Perceval.
(L.S.)
MARTIN WESTMACOTT.
CHARLES JOHN PERCEVAL. (L.S.)
.
MATTHEW A. SOUL.