IMPROVEMENTS IN PREPARING AND TREATING GUTTA PERCHA AND INDIA-RUBBER
Year: 1861

page_text: LETTERS PATENT to William Albert Shepard, of Pall Mall,in the County
of Middlesex, for the Invention of "IMPROVEMENTS IN PREPARING AND
TREATING GUTTA PERCHA AND INDIA-RUBBER,"
Sealed the 11th March 1862, and dated the 7th November 1861.
PROVISIONAL SPECIFICATION left by the said William Albert Shepard
at the Office of the Commissioners of Patents, with his Petition, on the
7th November 1861.
Jf
I, WILLIAM ALBERT SHEPARD, of Pall Mall, in the County of Middlesex,
do hereby declare the nature of the Invention for "IMPROVEMENTS IN PRE-
PARING AND TREATING GUTTA PERCHA AND INDIA RUBBER," to be as follows:-
This Invention has for its object improvements in preparing and treating
gutta percha and india-rubber. For these purposes in preparing gutta
percha, it is first thoroughly washed and cleansed by any one of the well
known methods used for that purpose which may be preferred. The gutta"
percha thus partially purified is then thoroughly masticated and placed in
an iron vessel, in which a vacuum is created and the air is thus exhausted'
from the pores of the gum. The gum is then charged with the fumes of
sulphur which are admitted into the vacuum, or a small quantity of sulphur
[Pries 8d:]

page_text: may be ground with the gum before it is placed in the vacuum vessel. The
gutta percha thus treated is next exposed to steam of a high temperature
which may be admitted into the vacuum vessel, the temperature varying
according to the different qualities of gutta percha which require different
degrees of heat to drive off the volatile impurities. The required heat of
the steam may, if desired, be obtained by superheating it, and the degrees
of heat may vary from 300 to 450. The gum is now once more thoroughly
masticated to free it from any lingering impurities and bring it into suitable
condition for mixing, and it is then ready to be combined with other ingre-
dients for the purposes of manufacture. By thus treating gutta percha in
the preliminary process it becomes highly purified, and so changed that
more uniform and more satisfactory results are obtained in the subsequent
processes of manufacture and vulcanization than by other methods. Gutta
percha thus prepared according to my Invention as above described, is next
combined with sulphur or certain compounds of sulphur, such as the hypo-
sulphite of lead, or zinc, or antimony, either by grinding or mixing by the
ordinary methods, and is then ready to be combined with various other
ingredients. With the gutta percha thus purified and combined, I mix
various ingredients to make the different articles of manufacture required,
and these ingredients vary according to the various uses to which the manu-
factured articles are to be applied. I mix with the prepared gutta percha
fibrous materials, prepared chalk, oxide and carbonate of lead, oxide of zinc,
carburet of iron or graphite, magnesia, vegetable oils boiled to a proper
consistency, emery, pitch, different kinds of tar, rosin, gums, coloring and
other materials, according to the kind of goods I wish to manufacture. These
compounds of gutta percha are then spread upon fabrics by means of callenders
or are formed in moulds, or otherwise as the case may require. The articles
thus manufactured are thenvulcanized in vulcanizing chambers, bysubjecting
them to different degrees of heat, varying from 25 to 450 Fahrenheit, accor-
ding to the character of gutta percha and compounds employed, and the
required uses of the goods.
In order to convert these compounds without the use of artificial heat, I
employin certain cases as a bath, a solution of thebisulphide of carbon in combi-
nation with bromine or chlorine, and the proportions of bromine or chlorine
are to be determined in the following manner, videlicit:-luto the bisulphide
of carbon pour bromine until the mixture assumes a color resembling that
of claret wine, or even a darker color. When chlorine is used, pass into
the bisulphide of carbon, chlorine gas until the bath becomes of a fine yellowish

page_text: green color. In either case the proportions of bromine or chlorine may be
determined by trial, by dipping into the bath pieces of the goods to be
subjected to treatment, until the desired effect is produced; when further
mixture or saturation of the bath is arrested.
For certain kinds of goods, it may be desirable to add to' the bath a
small quantity of benzole or naphtha.
Having thus described the different parts of my process, what I claim, is,―
First, the peculiar mode herein described of preparing and purifying.
gutta percha by my preliminary process.
Secondly, the mixture of the various ingredients above named with gutta
percha thus prepared and purified.
Thirdly, the vulcanizing of gutta percha goods, prepared' according to
my Invention.
And, lastly, the use of the bath for converting those goods as above
described.
.JA
SPECIFICATION in pursuance of the conditions of the Letters Patent; filed
by the said William Albert Shepard in the Great Seal Patent Office
on the 22nd April 1862.
TO ALL TO' WHOM THESE PRESENTS SHALL COME, I, WILLIAM
ALBERT SHEPARD, of Pall Mall, in the County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Seventh day of November, in the year of our Lord
One thousand eight hundred and sixty-one, in the twenty-fifth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said William Albert Shepard, Her special licence that I, the said 'William
Albert Shepard, my executors, administrators, and assigns, or such others
as I, the said William Albert Shepard, ny 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 PREPARING AND TREATING GUTTA PERCHA' AND INDIA
RUBBER," upon the condition (amongst others) that I; the said William 'Albert
Shepard, my exécutors or administrators, by an instrument in writing 'under
my, or their, or one of their hands and seals, should particularly describe and

page_text: 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 William Albert Shepard, do hereby
declare 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 thereof, that is to say :-
This Invention has for its object "improvements in preparing and treating
gutta percha and india-rubber. For these purposes in preparing gutta percha
it is first thoroughlywashed and cleansed byauy one of the well known methods
used for that purpose which may be preferred. The gutta percha thus
par-
tially purified is then thoroughly masticated, and placed in an iron vessel in
which a vacuum is created and the air is thus exhausted from the pores of the
gum. The gum is then charged with the fumes of sulphur, which are admitted
intothe vacuum,orasmall quantity of sulphur may be ground withthegum before
itis placed in the vacuum vessel. The quantity of sulphurinthispreliminary pro-
cess will vary in amount from one to one and a half, and sometimes two ounces
of sulphur to every ten pounds of the gum,according as the gum is good or poor,
but care must be taken that not sulphur enough is added to produce vulcaniza-
tion. The gutta percha thus treated is next exposed to a high degree of heat.
which may vary from 300 to 450 Fahrenheit according to the different qualities
of gutta percha, which require different degrees of heat to drive off the volatile
impurities, the best quality of guttapercha requiring the lowest degree of heat.
In the manufacture of articles where it is desirable to prevent any partial oxi-
dation of the gutta percha taking place at this high temperature, I admit into
the vacuum vessel air which has passed through highly heated tubes or through
a bath prepared by means of pumice stone, saturated with the prussiate of
potash or otherwise prepared to answer the purpose, or I apply the heat directly
to the gutta percha in vacuo which is preferable. This is especially important
in the manufacture of articles in which the compounds of the gutta percha,
either applied to fabrics or otherwise, are to be much exposed to the action of
the atmosphere; for a partial oxidation of the gutta percha in the preliminary
process causes a subsequent decay of that material, and the compound spread
upon the fabrics then cracks and, if subjected to wear, comes off. When the
above conditions are not required, steam may be used to impart heat in the
preliminary process. The time of this preliminary heating will vary from two
and a half to four hours. The gum is now once more thoroughly masticated or

page_text: kneaded to free it from any lingering impurities, which is very important, and
bring it into suitable condition for mixing, and is then ready to be combined
with other ingredients for the purposes of subsequent vulcanization and of.
manufacture. By thus treating gutta percha in the preliminary process it
becomes highly purified and so consistent that more uniform and more satis.
factory results are obtained in the subsequent processes of manufacture and
vulcanization than by other methods. In fact this preliminary process and the
masticating or kneading, or pressing between rolls are indispensable. Gutta
percha thus prepared according to my Invention as above described, is next
combined with sulphur or certain compounds of sulphur, such as the hyposul-
phite of lead or any equivalent compound of sulphur, by grinding and mixing
with care to give a proportion of one ounce of sulphur to a pound of gutta
percha. But the use of sulphur is much preferred. With the gutta percha
thus purified and combined, I mix various ingredients to make the different
articles of manufacture required, and these ingredients vary according to
the various use to which the manufactured articles are to be applied. I mix
with the prepared gutta percha fibrous materials, prepared chalk or Paris
white, carbonate of lead, oxide of zinc, carburet of iron, or graphite magnesia,
vegetable oils boiled to a proper consistency, emery, pitch, different kinds
of tar, gums, coloring, and other materials according to the kind of goods.
For fine cloths and clothing generally a good mixture will be in the
following proportions, namely,―
To 16 lbs. of gutta percha add 4 lbs. litharge, 2 lbs. of white lead and the
desired colouring materials, but with best quality gutta percha lb. of mag-
nesia may be added to this compound, and 1 lb. Paris white. The oxide
of zinc may be substituted for the white lead and in the same proportion.
In the manufacture of coarser goods, such as banding, hose, steam pack-
ing, &c. 5 lbs. litharge may be used instead of 4 lbs. in the above mixture,
and 3 lbs. of white lead instead of 2 lbs. and 1 lb. of Paris white; the other
proportions remaining the same.
To this compound 2 to 3 lbs. of scraps of gutta percha goods may be
added. In coarse goods Paris white may be used instead of the litharge.
For hose or pipes to be used underground, or for large pipes for distributing
liquid manure, Paris white may be used instead of the litharge in proportion of
5 lbs. to 16 los. of the gum, and to this may be added 5 lbs. of plumbago mixed
with linseed oil of a thick consistency. This kind of hose may also be made
by the use of tar in mixing the compound. In making floorcloth and similar
articles Paris white is used in proportions as above, with one half the propor-

page_text: tion of plumbago and oil, and a considerable quantity of fibrous material may
be added, the amount depending upon the quality of the gutta percha, but it
can be readily determined by a skilled workman. In making friction surfaces,
lead and Paris white must be used, mixed with emery, and these ingredients
may enter largely into the compound, the whole being in the proportion of 6 lbs.
to 4 of gutta percha, and the proportion of emery depending on the use to which
the friction surface is to be applied. The above proportions are not constant being
for a fair quality of gutta percha, and being susceptible of change to a higher pro-
portion of ingredients for best quality of gutta perchia, and a less proportion for
poorer qualities. Great care must be taken to mix the different ingredients com-
pletely with the gutta percha, so that the whole mass may be of one uniform con-
sistency. It will be found necessary with mixtures where the ingredients to
be added to the gutta percha do not mix easily and consistently by themselves,
to mix the ingredients separately with separate portions of gutta percha, and
then to grind together and mix these partial compounds thoroughly into one.
Where the ingredients are few, and in large proportions to the gutta percha,
they may be mixed one at a time with the gutta percha, adding each ingre-
dient after the preceding one has been thoroughly and uniformly incorporated
with the gum.
When the ingredients mix by 'themselves easily and con-
sistently they may be so mixed, and the compound then mixed with the
gutta percha; but it is necessary that the sulphur should be incorporated
first and separately by itself with the gum in all cases.
It is absolutely'
necessary that the mixing should be conducted, as above, with great care
for imperfect mixing is one of the chief causes of the cracking of the
surface of fabric goods.
The mixing is best accomplished by mixing rolls, and these rolls should be
kept at a temperature from 150° to 170° Fahrenheit. When the paste is
found to be of a thick consistency in the process of mixing by the rolls, it may
be softened by adding to it vegetable oils which have first been boiled; these
compounds of gutta percha are then spread in a plastic condition upon fabrics
of different kinds and qualities according to the kind and quality of articles
required by means of calenders, or are formed in moulds or otherwise, as may
be desired. To give a smoother or more highly finished surface to the goods
than is done by the calenders, I place alternate layers of the fabrics prepared
as above and of sheet zinc, a zinc plate being at the top and bottom of the
pile, and I then subject the pile to a heavy pressure by passing it between
powerful rollers, or by press rolls, being preferred. When stamped or orna-
mented gutta percha cloths are required, I use printing plates in a similar

page_text: manner as I use the smooth plates to give the impression, or I run a web of
stamped cloth with the raised side next to the freshly-spread gutta percha
surface through the calenders which will impart the impression of the figures
on the cloths to the gutta percha. The articles thus manufactured are then
vulcanized in vulcanizing chambers by subjecting them to different degrees of
heat varying from 250 to 450° Fahrenheit according to the character of the
gutta percha and compounds employed, and the required uses of the goods.
If required, the manufactured articles are then plunged into a hot alkaline
bath to cleanse the surface, and give to them a brighter and more uniform
appearance. The goods subjected to this bath should then be washed in water,
and dried in the sun. In very fine goods this bath may be avoided by
attempting only a low degree of vulcanization. When very thin or light
fabrics are required, a solution of gutta percha may be. brushed upon the
surface of such fabrics. This solution may be made by solving the gutta
percha after it is prepared, as heretofore described, for preliminary treating in
any one of the known solvents of the gum which may be preferred for that
purpose. The fabrics thus prepared may be plunged into the converting bath,
as herein-after described, and according to the directions there given.
When it is desired, a double fabric may be made by placing together the
spread or gum-covered surfaces of two pieces of fabric, and putting them
together between rolls. In order to convert these compounds of gutta percha,
without the use of heat in vulcanizing chambers, I use in certain cases as a
bath a solution of the bisulphide of carbon in combination with bromide or
chlorine, and the proportions of bromine or chlorine are to be determined in
the following manner, vizt.:-Into the bisulphide of carbon pour bromine until
the mixture assumes a colour resembling that of claret wine, or even a darker
colour; when chlorine is used, pass into the bisulphide of carbon chlorine gas
until the bath becomes of a fine yellowish green colour. In either case the
proportions of bromine or chlorine may be determined by trial by dipping
into the bath pieces of the goods to be subjected to treatment until the desired
effect is produced, when further mixture or saturation of the bath is arrested.
The time during which the goods are to remain in the bath will vary from
15 to 60 seconds according to the degree of flexibility or rigidity required in the
articles, and to the thickness of the compounds. The length of time must be
arrived at before using the bath, by experimenting on a piece of the articles
to be converted; for certain kinds of goods it may be desirable to add to the
bath a small quantity of benzone or naptha to temper the bath. The use
of this bath may be applied to articles made of india-rubber or india-

page_text: rubber nixed with gutta percha, which has been treated by my preliminary
processes.
Having thus described the different parts of my process, I do not claim
the vulcanization of gutta percha, nor the distilling off impurities; but what
I claim is,―
First, the mode herein described of preparing and purifying gutta percha.
Secondly, the method herein described of mixing the various ingredients
above named with gutta percha thus prepared and purified, substantially
in the manner above described.
Third, the vulcanizing of gutta percha goods prepared and compounded
according to my Invention.
Lastly, the use of the bath, herein explained, for converting goods
prepared, as described.
In witness whereof, I, the said William Albert Shepard, have hereunto
set my hand and seal, this Twenty-second day of April, in the year of
our Lord One thousand eight hundred and sixty-two.
WM. A. SHEPARD. (L.S.)