IMPROVEMENTS IN THE MANUFACTURE OF ARTICLES OF HARD VULCANIZED INDIA-RUBBER AND GUTTA PERCHA AND SIMILAR GUMS
Year: 1858

page_text: LETTERS PATENT to Charles Cowper, of No. 20, Southampton Buildings,
Chancery Lane, in the County of Middlesex, Patent Agent, for the
Invention of "IMPROVEMENTS IN THE MANUFACTURE OF ARTICLES OF HARD
VULCANIZED INDIA-RUBBER AND GUTTA PERCHA AND SIMILAR GUMS."-A
communication from Gustavus Cuppers, residing at College Point, in
Long Island, in the State of New York, in the United States of
America.
Sealed the 12th April 1859, and dated the 14th October 1858.
PROVISIONAL SPECIFICATION left by the said Charles Cowper at the
Office of the Commissioners of Patents, with his Petition, on the
14th October 1858.
I, CHARLES COWPER, of No. 20, Southampton Buildings, Chancery Lane,
in the County of Middlesex, Patent Agent, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN THE MANUFACTURE OF ARTICLES OF
HARD VULCANIZED INDIA-RUBBER AND GUTTA PERCHA AND SIMILAR GUMS," to be as
follows:-
The Invention is applicable to india-rubber and gutta percha, and similar
gums, or varieties of those gums which are capable of being vulcanized by

page_text: combination with sulphur or materials containing sulphur, and the application
of heat. In the ordinary mode of manufacturing hard india-rubber articles,
especially when of considerable thickness, great inconvenience arises from the
contraction of the articles during the hardening process. The prepared soft
compound of india-rubber or gutta percha with sulphur and other ingredients
is placed between tin or tinfoil and squeezed in moulds preparatory to
subjecting it to the action of heat. The articles shrink and crack, and
frequently require a great deal of extra labour by filing and cutting to finish
them.
a
The present Invention obviates these defects in the following manner:-
The compound of india-rubber or gutta percha with sulphur or other materials
is prepared in the usual manner, and it is then placed in the mould made of
cast tin, or cast brass, or pressed tin, or any other suitable material of which
moulds are made. It is then subjected to the action of steam or hot air, or
heat of any kind, during period of from one half an hour to three hours, or
more or less, according to the proportion of sulphur and the degree of heat
employed, which may be from about two hundred and ninety to three hundred
degrees of Fahrenheit's thermometer, or more or less; the larger the pro-
portion of sulphur and the higher the temperature, the shorter will be the
time required, and vice versa. The article is then withdrawn from the heat
and removed from the mould, and it is then in a partially hardened state.
Any blisters, holes, or other imperfections on the surface are now moistened
by a solvent or liquid compound of india-rubber or gutta percha, and are
filled up and smoothed with the original compound before mentioned, and
pressed again in the mould, care being taken to have the joints of the mould
water-tight during the heating process by means of small strips of india-rubber
inserted between the joints, or otherwise. The parts are then pressed firmly
together by screws, or otherwise, and again exposed to heat for about half an
hour to three hours, or more or less, when the material will still be in a
partially hardened state. The article is then removed from the heat and from
the mould, and if still imperfect is again repaired and perfected as before,
although this second repairing is not generally requisite. The article is then
placed loosely in a box without the mould; the box is then closed hermetically
and exposed to heat for about six or eight hours, or until the article is com-
pletely hardened, after which the box is removed and opened, and the process
is completed.
The form of the article will be found to be very perfect, although somewhat
smaller than the mass originally contained in the mould. In some cases, as

page_text: for combs and articles of small thickness, the articles are partially hardened
and repaired as herein-before described, and are then replaced in the mould,
and the heating or vulcanizing or hardening process is completed while they
are in the moulds. When the article is to be very finely and elaborately
ornamented, the process is varied by employing two moulds, one of which
gives the general form or main body of the article, and the other the fine.
impressions of the ornament. The first or coarse mould is employed in forming
the article and repairing imperfections, as herein-before described, and about
one-half or three-quarters of the ultimate degree of hardening is produced in
this mould, still leaving the material in such a state as to receive impressions
on its surface by moderate pressure. It is then removed from the heat and
placed in the second or fine mould, which is firmly pressed together by screws
or otherwise, so as to convey the impression to the material. The joints of
the mould are made watertight, as before, by strips of india-rubber, soft
compound, or otherwise. The article with the mould is then subjected to
heat until the hardening process is completed, when the impressions will be
found clear and distinct.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Charles Cowper in the Great Seal Patent Office on the
13th April 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
COWPER, of No. 20, Southampton Buildings, Chancery Lane, in the County of
Middlesex, Patent Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fourteenth day of October, in the year of our Lord
One thousand eight hundred and fifty-eight, in the twenty-second year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Charles Cowper, Her special licence that I, the said Charles Cowper,
my executors, administrators, and assigns, or such others as 1, the said
Charles Cowper, my executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times there-
after 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 "IMPROVE-
MENTS IN THE MANUFACTURE OF ARTICLES OF HARD VULCANIZED INDIA-RUBBER AND

page_text: GUTTA PERCHA AND SIMILAR GUMS," communicated to me from Gustavus Cuppers,
residing at College Point, in Long Island, in the State of New York, in the
United States of America; upon the condition (amongst others) that I, the
said Charles Cowper, 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 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 Charles Cowper, do hereby declare
the nature of the 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 thereof, that is to say :-
I deem it proper to state that in using the words "india-rubber" and gutta
percha in this Specification, I mean to include all the vulcanizable gums
either alone or mixed together, or in combination with other substances; and
in using the term "compound," I mean to designate the combination of
sulphur or materials containing sulphur with india-rubber or gutta percha, or
the gums or mixtures or combinations aforesaid.
Hardened or vulcanized india-rubber and gutta percha have of late been
used for the purpose of manufacturing articles of commerce, but the more
general manufacture and introduction of hardened india-rubber and gutta
percha goods have been limited and restricted by the difficulty of making
these articles into every desired shape and form. The object of the present
Invention is to overcome this difficulty.
One of the methods of manufacturing hardened india-rubber and gutta
percha goods heretofore in use, is as follows:-The prepared soft compound,
consisting of india-rubber or gutta percha combined with sulphur and other
ingredients, is put between leaves of tinfoil and pressed in brass or other
moulds or forms, preparatory to subjecting it to the action of heat. With
articles that do not exceed in thickness three-sixteenths of an inch, this
method answers the purpose sufficiently well; but articles having convex,
concave, or uneven surfaces which exceed that thickness, shrink, and thereby
become misshapen, so as to be useless without the application of a great
amount of extra labour, as herein-after mentioned. To obviate this result,
sheet tin has been substituted for tinfoil, but it is found that although this
method diminishes the shrinkage, there are cracks and a rough unseemly
surface. To make articles thus produced fit for use, it was necessary to

page_text: bestow upon them a great deal of extra labour by filing, rasping, sawing,
cutting, and smoothing the same.
In consequence of the unsatisfactory character of these results, the manu-
facture of hardened india-rubber and gutta percha has hitherto been chiefly
restricted to articles requiring no considerable thickness, or to hollow articles,
or to goods in which a perfect surface was not essential, or to high-priced
articles. But the great mass of articles for which hard india-rubber and
gutta percha are so eminently fitted, such as handles for knives, forks, canes,
whips, sabres, daggers, tools, umbrellas, knobs for doors, windows, shutters
and furniture, butt ends for muskets, rifles, and other fire-arms, balls, clubs,
pipes, and so forth, have not been manufactured in large quantities, on account
of the defects and costliness of the process herein-before referred to. By
proceeding in the following manner the aforesaid defects are avoided or
corrected: In the first place the india-rubber or gutta percha is prepared
for hardening in the usual manner, and is placed in the mould made of cast
tin, or cast brass, or pressed tin, or other suitable material. It is then
subjected to the action of steam or hot air, or heat of any kind during a
period of from one half an hour to three hours, the length of time depending
on the proportion of sulphur mixed with the india-rubber and other circum-
stances. Thus, when half a pound of sulphur is mixed with one pound of
india-rubber, and the heat is about from two hundred and ninety to three
hundred degrees of Fahrenheit's thermometer, the time for leaving it in the
mould will be about one hour. If less sulphur be mixed with the rubber or
less heat used, the time must be increased proportionally. If the heat is
greater than about three hundred degrees, less than an hour will be required.
It is then removed from the heat, and the mould is removed from the india-
rubber or gutta percha, which by this time is in a partially hardened state.
Any blisters, holes, or other imperfections on the surface are now moistened
by a liquid compound or solution of india-rubber or gutta percha, and are
filled up and smoothed with the original compound before mentioned and
pressed again in the mould, care being taken to have the joints of the mould
water-tight during the heating process by means of small strips of india-rubber
inserted between the joints, or otherwise. The parts of the mould are then
pressed firmly together by screws or otherwise, and the whole is again replaced
in the heat, leaving it there from about one half an hour to three hours, when
the compound will still be partially hardened. It is then again withdrawn
from the heat and removed from the mould, and if the shape be still imperfect
it is again perfected in the manner herein-before described; but if the form be

page_text: perfect, the article is placed loosely in a box without the mould. The said
box containing the shaped articles is then closed hermetically, and exposed to
the heat until the articles are completely hardened, which may require six or
eight hours' exposure to heat, after which the box is removed and opened, and
the process is completed. The form of the articles will then be found to be
perfect, although somewhat smaller than the mass originally contained in the
mould. It will generally be sufficient to remove the articles only once from
the mould for the purpose of repairing or patching. Much will depend upon
the particular mould used and the form and thickness of the article, and a
little practice will enable the workman to decide whether one removal from
the mould is sufficient or not. Articles of no great thickness, such as combs,
are partially hardened and the imperfections repaired in the manner berein-
before described, and they are then replaced in the mould, and the vulcanizing
process is completed while they are in the mould.
In articles of considerable thickness the great contraction takes place
during the last part of the heating process, and the article not being in
contact with the mould at that time, the contraction proceeds in an uniform
manner.
The methods herein-before described are more particularly applicable for
the purpose of obtaining plain surfaces or formis with comparatively large
ornaments. When, however, the article is to be finely and elaborately
ornamental, the above-described method is varied by employing two moulds,
one for the main body of the rubber, and the other for the impressions of the
ornaments. The mould for the main body of the rubber is used for the
purpose of repairing imperfections in the manner herein-before described, and
therein is obtained about one-half or three-quarters of the ultimate degree of
hardness. The degree of hardness thus obtained must be such as to enable
the india-rubber or gutta percha to still receive impressions on its surface by
moderate pressure. The article is then removed from the heat and from the
inould, and is deposited in another mould containing the finely marked orna-
ments. The parts of this mould are to be firmly pressed together by the
application of screws or otherwise, so as to convey the impression to the india-
rubber or gutta percha. In joining the two or more parts together, proper
care is to be taken to make the joints water-tight by means of small strips of
india-rubber, soft compound, or otherwise. The india-rubber or gutta percha
with this mould is then again subjected to the action of heat until the
hardening process is completed, when the impressions will be found clear and
distinct.

page_text: Having now described the nature of the said Invention, and in what
manner the same is to be performed, I wish it to be understood that I do not
claim the vulcanizing or hardening process generally, but what I claim is the
improvements in the manufacture of articles of hard vulcanized india-rubber
and gutta percha and similar gums, by partially hardening and repairing or
perfecting the same one or more times, and then completing the hardening
or vulcanizing process, as herein-before described.
In witness whereof, I, the said Charles Cowper, have hereunto set my
hand and seal, this Twelfth day of April, One thousand eight hundred
and fifty-ninc.
CHARLES COWPER. (L.s.)