Improvement in the Art or Process of Waterproofing Leather.
Year: 1894

page_text: COMPLETE SPECIFICATION.
Improvement in the Art or Process of Waterproofing Leather.
I, EDWARD HENRY LEWIS, a citizen of the United States, of No. 304 North
Eighth Street in the City of St. Louis, State of Missouri, United States of
America, Gentleman, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
This invention relates to a new and useful process of waterproofing leather, being
particularly applicable to that class of leather used in the manufacture of shoes
known as sole-leather, and consists in the process hereinafter described of rendering
leather pliable and waterproof, by subjecting the same to a hot bath composed
of molten wax and a solvent, penetrating, volatile vehicle, after which the leather
is removed and permitted to dry, during which drying process the solvent vehicle
volatilizes or passes off into an aeriform state, leaving a deposit of wax in the pores
of the leather, which completely fills the same and renders the leather flexible and
pliable and perfectly waterproof.
This invention is an improvement over the process described in United States
Letters Patent granted to Frederick Riegert on March 7th, 1893, No. 492,836,
wherein beeswax was placed in a hermetically-sealed vessel and subjected to a heat
of about 180 degrees Fahrenheit. To this was added, for each pound of beeswax,
two pounds of spirits of turpentine, and the temperature permitted to lower to about
one hundred degrees Fahrenheit, at which time the leather was immersed in the
bath and steeped for ten or fifteen minutes, after which it was taken out and
subjected to a pounding or pressing action, such as a hammer, or between rolls,
which compressed the leather and closed the pores thereof.
The process, as above described, which is set forth in the before-mentioned
Patent, has its objections, among which may be mentioned the exudation of the
waterproofing material during the process of pounding or rolling, which material
should completely saturate the leather and fill its pores, in order to give the best
results. Again, in closing and tightening the pores of the leather treated, not only
was the waterproofing material forced out as before stated, but, by the disturbance
of the outer skin of the leather, that portion of the waterproofing material
which had penetrated deeply would be confined, and the solvent vehicle, which
should have had access to the exterior, in order that evaporation might take place,
was cut off.
In this present invention, I dispense entirely with the pounding or pressing
action on the leather, and, instead thereof, leave the pores of the leather in their
normal condition, until complete evaporation of the solvent vehicle and congealment
of the wax takes place, when the leather is ready for use.
In so dispensing with the pounding and pressing step of the old process, I not
only reduce the cost of production, of a perfectly waterproof leather, but save
considerable time and attain a better result.
In following my improved process, I take the leather either in its original
state, as it comes from the tannery, or after it is cut in the proper shape, and
immerse it in a bath of wax and a volatile, solvent vehicle, which bath is heated
to about from 150 to 170 degrees Fahrenheit, where I let it remain for a space of
time sufficient to permit penetration of the pores of the leather by the hot wax and
its solvent vehicle. This generally takes from five to ten minutes.
The leather is then taken out, and, preferably, permitted to dry, in which
drying process the volatile solvent will pass off into an aeriform state, leaving
a deposit of wax in the pores of the leather, which renders the same perfectly
waterproof.

page_text: I have found it advantageous in the immersion of the leather in the hot bath,
particularly where it is cut in shape for soles, to arrange the same in a rack or
tray, which not only facilitates the handling thereof, but enables the hot wax and
solvent vehicle to penetrate both sides readily.
The ingredients composing the hot bath are, preferably, for the sake of cheapness,
beeswax and naptha; but I do not wish to be understood as confining myself
particularly to their use, as there are other waxes and oils which congeal upon
cooling and which could be as advantageously used. For illustration, mineral waxes,
such as paraffine, etc., and spermaceti, etc.; and, as a substitute for naptha, there
are many well-known volatile spirits, such as turpentine, benzine, benzole, etc.,
which could be used as a solvent and vehicle for the wax, to carry the same into
the pores of the leather, and, by volatilization, deposit the wax in the pores.
The hot bath made of this filling material, of wax and a volatile solvent
vehicle, should be mixed in such proportions, preferably of about equal parts, as to
enable efficient penetration by the vehicle and saturation of the leather by the
compound.
The process and compound, as above described, is particularly designed for the
treatment of leather tanned under the old process, where it is subjected to the
action of the acids contained in the tanning bark; but I have found that the leather
tanued under the chemical or hot liquor process is of a different nature and has to
be treated slightly different from that first mentioned. By this, I mean that
chemically-tanned or hot-liquor-tanned leather has a very dry grain, amounting,
almost, to brittleness, and when the channel is formed in the sole, the leather cracks
at the junction of the tongue. In order to make this chemically-tanned leather
pliable, so that it can be operated upon successfully by the channeling machine, I
add turpentine to the waterproofing compound, which addition I have found to be
very effective, and because of making a chemically-tanned shoe sole fit for operation
thereon by a channeling machine, at the same time rendering it absolutely waterproof
and pliable.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed I declare that what I
claim is :
1. The herein-described process of rendering leather pliable and waterproof, which
consists in subjecting the same to a hot bath composed of molten wax and a
penetrating, volatile, solvent vehicle, then removing the same, and permitting the
vehicle to volatilize and leave a deposit of wax in the pores of the leather,
substantially as described.
2. The herein-described process of treating leather to render the same pliable
and waterproof, which consists in immersing the leather in a bath composed of
wax and a volatile solvent, heated to about 150 to 170 degrees Fahrenheit, leaving
the leather in the bath until completely saturated, and finally removing the same,
when the solvent vehicle volatilizes, leaving a deposit of wax in the undisturbed
pores of the leather, which deposit completely fills the same, substantially as
described.
3. The process herein described of waterproofing leather soles for shoes, which
consists in subjecting the same to a hot bath of molten wax and a solvent vehicle,
the soles being subjected to the bath in such manner that both sides and edges are
acted upon, substantially as described.
4. The process herein described of rendering shoe soles pliable and waterproof,
which consists in subjecting the same to a hot bath composed of molten wax, a
solvent, volatile vehicle, and turpentine, substantially as described.
Dated the 20th day of February 1894
PHILIP M. JUSTICE,
Chartered Patent Agent, London,
For the Applicant.