IMPROVEMENTS IN THE PREPARATION AND HARDENING OF LEATHER FOR BOOTE SOLES,STRAPS AND BANDS, AND OTHER PURPOSES
Year: 1864

page_text: LETTERS PATENT to Henry Kemp and Francis John Kemp, of Holloway
Road, in the County of Middlesex, Gentlemen, for the Invention of
st IMPROVEMENTS IN THE PREPARATION AND HARDENING OF LEATHER FOR BOOT
Sealed the 13th January 1865, and dated the '7th October 1864.
PROVISIONAL SPECIFICATION left by the said Henry Kemp and Francis
John Kemp at the Office of the Commissioners of Patents, with 'their.
Petition, on the 7th October 1864.
We, HENRY KEMP and FRANCIS JOHN KEMP, of Holloway Road, in the
County of Middlesex, Gentlemen, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN THE PREPARATION AND HARDENING OF LEATHER
FOR BOOT AND SHOE SOLES, STRAPS, AND BANDS, AND OTHER PURPOSES," to be as.
follows:-
My Invention of improvements in the preparation and hardening of leather
for boot and shoe soles, straps, and bands, and other purposes, has for its
object to harden and strengthen leather and render it waterproof and more
durable than heretofore, so that leather, even of inferior quality, may be.
employed for various purposes in the arts for which it has hitherto been
in applicable. This objectis effected by causing the leather to be impregnated.
with a preparation or compound composed of wood, tar, caoutchouc dissolved
in naphtha, gutta percha, or other analogous gum dissolved in a suitable
Die d

page_text: solvent, to which is added a proper proportion of shell-lac for the purpose of
hardening the compound when dryand. facilitating the drying. The particular
kind of tar which I prefer to use is tar obtained by the destructive distillation
of hard woods, such as are used in the preparation of pyroligneous acid and
for other similar purposes, and for this reason I denominate the tar pyro-
ligneous tar. Of this tar I take, say, from 10 to 12 pounds, and I add
thereto from 2 to 4 ounces of caoutchouc, gutta percha, or other analogous
gum dissolved in any of the usual solvents. To these ingredients are added
from 6 to 8 ounces of shell-lac, more or less, according to the degree of
hardness required. The whole of the ingredients are attenuated to the p
proper
degree of liquidity by the addition of methylated spirit, the proportion of
which must depend upon the consistence of the pyroligneous tar employed
and on the quality or porosity of the leather to be operated upon. For some
purposes, such as for coating metallic surfaces with the prepared skins or
leather, I add to the above compound about 10lbs. of asphaltum and oil of
tar, the proportions of the other ingredients remaining about the same.
In carrying out my Invention I place the skins or pieces of leather to be
operated upon in a close vessel or cylinder with the ingredients or liquid
compound above mentioned, which, as before mentioned, must be attenuated
to a proper. state of liquidity by the addition of a suitable proportion of the
methylated spirit. I then exhaust the air from the cylinder by means of a
syringe, air
pump or other suitable exhausting apparatus, so as to allow the
chemical compound or solutionto permeate through or impregnate the leather.
This process is much facilitated by subsequently forcing air under pressure
into the cylinder above the liquid compound, which will thereby be forced
through the pores of the leather. To effect the proper impregnation of the
leather I sometimes adopt the plan in common use for injecting fluids into
the pores of wood for its preservation. This plan consists in first exhausting
the air in the cylinder in which the leather is placed,and while the exhaustion
continues admitting the compound by means of tubes and stop-cocks from a
tank, and when the cylinder is thus filled the pressure before alluded to is
put on, when the operation of injection will be completed. The process is
facilitated by heating the solution to from 80 to 90 degrees Fahr. After the
leather has been thus subjected to the action of the solution for about a
quarter of an hour it may be removed from the cylinder, and the several pieces
should be placed under pressure for the purpose of expelling the superabun-
dant liquid and consolidating the substance of the leather.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed.
by the said Henry Kemp and Francis John Kemp in the Great Seal
Patent Office on the 7th April 1865.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, HENRY
KEMP and FRANCIS JOHN KEMP, of Holloway Road, in the County of Mid-
dlesex, Gentlemen, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters,
Patent, bearing date the Seventh day of October, in the year of our Lord
One thousand eight hundred and sixty-four, in the twenty-eighth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto us, the
said Henry Kemp and Francis John Kemp, Her special licence that we, the
said Henry Kemp and Francis John Kemp, our executors, administrators,
and assigns, and such others as we, the said Heary Kemp and Francis John
Kemp, our 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 PREPARATION
AND HARDENING OF LEATHER FOR BOOT AND SHOE SOLES, STRAPS, AND BANDS, AND
OTHER PURPOSES," upon the condition (amongst others) that we, the said Henry
Kemp and Francis John Kemp, by an instrument in writing.under our hands
and seals, or under the hand and seal of one of us, 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 we, the said Henry Kemp and Francis John
Kemp, do hereby declare the nature of our said. Invention, and in what
manner the same is to be performed, to be particularly.described and ascer-
tained in and by the following statement (that is to say):
Our Invention of improvements in the preparation and hardening of leather
for boot and shoe soles, straps, bands, and other purposes, has for its object to
harden and strengthen leather and render it waterproof and more durable
than before, so that leather of inferior quality may be employed for various
purposes in the arts and manufactures for which it has hitherto been in-
applicable. This object is effected by impregnating the leather with a pre-
paration of tar dissolved in spirit, caoutchouc orgutta percha or other suitable
gum dissolved in naphtha or other suitable solvent, to which is added a proper

page_text: proportion ofdissolved shell-lac for the purpose of hardening the other mate-
rials when dry and facilitating the drying of the articles impregnated. The
tar should be that obtained by the destructive distillation of woods, or that
which is known in commerce as carbolic acid or impure kreasote, obtained by
distillation or otherwise from coal tar or any kind of tar. We prefer to use
wood tar, it may be termed pyroligneous tar, because produced in the process
of manufacturing pyroligneous acid. It is also obtained from charcoal during
carbonization for gunpowder or other purposes. The solvent for the tar is
methylated spirit of about 60° above proof, or pure spirits of wine. To one
gallon of tar we use about one quart of spirit (more or less, according to the
viscidity of the tar and the degree of liquidity most convenient for injecting
into the leather). The shell-lac should be first dissolved in the spirit, a day
or two being required for this purpose, in the proportion of two to eight
ounces to the quart of spirit, or an aqueous solution of shell-lac may be
obtained by mixing it with common borax or the biborate of soda and boiling
water. We do not confine ourselves to any particular mode or process for
injecting the leather or arranging the materials, but the plans herein-after
described may be convenient ways of effecting the object of our Invention.
1. According to one plan we place the leather in a close vessel or cylinder
and then cover it with the compound (in which dissolved india-rubber,-shell-
lac, and tar, in aforesaid and herein-after proportions, are all held together in
solution). We exhaust the air from the cylinder by means of a syringe, air
pump, or other convenient exhausting apparatus, so as to allow the chemical
compound or solution to permeate through or impregnate the leather when it
is admitted into the chamber. This process of impregnation may be facilitated
by forcing air under pressure into the cylinder above the liquid compound,
which will thereby be more easily forced through the pores of the leather.
2. A second plan for effecting the impregnation of the leather is as follows:
-Having exhausted the air from the cylinder in which the leather is placed,
then, whilst in vacuo, we admit the compound as above by means of tubes
(provided with stop-cocks) from a tub or other reservoir, and when the
cylinder is thus filled the pressure above alluded to is put on, so as to force
the liquid compound-through the leather.
3. A third plan is to put the leather into a receiver and exhaust the air
Tanks holding the solution are placed some fifteen feet (more or less, as is
found most convenient) above the receiver. These tanks are provided with
suitable stop-cocks or ordinary taps and tubes to allow the fluid to run from
the elevated tank into the receiver, and by this means fully inject the leather
while in vacuo by hydraulic pressure.

page_text: The above three plans apply to saturation only. In any case the leather
must be submitted to mechanical pressure in order to expel the superfluous
fluid, and then set aside to dry. When dry the leather should be either rubbed
with a solution of caoutchouc in the proportion of three to four ounces to a
gallon of mineral naphtha or other suitable solvent, or the leather may be
again placed in a cylinder and impregnated with the latter solution by either
of the above processes and then again pressed and dried..
4. A fourth plan is as follows:-After exhausting the air from the leather
in the cylinder admit the solution of india-rubber in naphtha, then take out
the leather and expose it to dry, when dry submit it again to exhaustion in
the receiver, and then admit the solution of wood, tar, and shell-lac combined,
then subject the leather to severe pressure for twenty-four hours. When
nearly dry rub in a solution of shell-lac, eight ounces to a gallon. of
methylated spirit, by means of a. piece of sponge, tow, or cotton waste, or
other suitable material, which gives the whole a polish..
5. A fifth plan is as follows:-After exhausting the air out of the leather
as above described, we admit it solution compound of equal parts of tar and
the dissolved india-rubber in the proportion of four to eight ounces of india-
rubber to a gallon of the solvent.
After saturation in vacuo, place the leather under moderate pressure, when
dry replace the leather in the exhauster or receiver, and then admit a solution
compound of four to eight ounces of shell-lac to a gallon of methylated spirit.
After this, subject the leather to severe pressure and again dry, when nearly
dry, rub in by a sponge, tow, or cotton waste, the solution of shell-lac to give
the whole a polish. In any case of exhausting the air it may be done with or
without a vacuum gauge. Whatever plan is adopted it may sometimes be
found that some pieces of leather may not be perfectly saturated. It is well
to examine all the pieces, and some that appear softest should be cut through
to test the completeness of saturation); if found not complete the process of
saturation should be repeated. Whatever plan of impregnation be adopted,
the process may probably be facilitated by heating the solution to from eighty
to ninety degrees of Fahrenheit. In any case the drying may be effected by
exposing the leather to the atmosphere, or in any rooms, or in rooms heated
to the temperature of eighty degrees by hot-water pipes, or a desiccating
apparatus, or by any other arrangement that may be preferred or found
most convenient.
The Invention is applicable to any and all sorts of leather. We prefer to
operate on that kind of leather known in the leather market as shoulder
leather, as it is more porous and less valuable than some other parts of the hide.

page_text: Skins may be subjected to the process whole or in pieces of any size, but for
boot and shoe soles, straps, harness, and other special purposes we prefer the
leather to be first cut or stamped to the required size. Boot and shoe soles
are more easily sewn within two or three weeks after the preparation of the
leather has been effected, but they can be easily pegged or rivetted after the
lapse of a much longer time. They should be under all circumstances well
dried before being used. Hides improved by this process may be used for
any sort of clothing or coverings. And as a medium for firm adhesion of
the prepared leather we employ asphaltum or mineral tar with shell-lac
dissolved in methylated spirit in combination with caoutchouc dissolved in
naphtha, the compound should be heated to seventy or eighty degrees.
Having now described our Invention of improvements in the preparation
and hardening of leather, and having explained several modes of carrying the
same into effect, we claim as the Invention secured to us by Letters Patent
as aforesaid, preparing and hardening leather by the application of the
liquid compounds above described, and subsequent pressure.
In witness whereof, we the said Henry Kemp and Francis John Kemp,
have hereunto set our hands and seals, this Fourth day of March, in
the year of our Lord One thousand eight hundred and sixty-five.
Sigued, sealed, and delivered by the
said Henry Kemp and Francis
John Kemp in the presence of
C. H. BINSTUD,
Sol. & Notary Public,
Portsmouth.
H. KEMP.
(L.S.)
FRANCIS J. KEMP. (L.s.)