Process for the Removal of Lime from Hides and Skins after Treatment in the Lime Bath.
Year: 1895

page_text: Date of Application, 5th Dec., 1895
Complete Specification Left, 31st Aug.. 1896-Accepted, 3rd Oct., 1896
PROVISIONAL SPECIFICATION.
Process for the Removal of Lime from Hides and Skins after
Treatment in the Lime Bath.
I, ADOLPHE BROGARD, of Mörchingen, Lothringen, Germany, Tanner, do
hereby declare the nature of this invention to be as follows:-
The preparation of hides and skins for tanning commences, as is well known, by
placing the same, after washing in water, for a certain time in a lime bath in
which they swell, so that after removal from the bath they can be readily freed
from the hairs and fleshy or mucous constituents by scraping with a knife. When
this has been done, it is necessary to remove from the hides or skins the adhering
lime particles which would otherwise soon render them hard and brittle. This has
heretofore been done by placing the hides or skins in a revolving drum filled with
water, whereby the coarser particles of lime were removed. The hides and skins
were then placed on a block and scraped by means of a stone scraper, whereby the
lime was pressed out. As even by this means all the lime was not removed, the
hides were again scraped with a sharp knife.
During the scraping with the stone and the knife, the hide had to be repeatedly
dipped into water, because it became hard.
After this mechanical treatment the hides and skins were placed in the tan pit
for the tanning process.
The present invention has for its object to effect the removal of the lime from
the hides and skins in a more convenient, reliable and expeditious manner, and it
consists in subjecting them, after they have be taken out of the lime bath, and
the hairs &c. have been removed therefrom, to the action of a dilute acid or potash
solution, in which they are left for a short time, say about two minutes, being
advantageously moved about during this time in order that all parts may come in
contact with the acid or potash solution.
The acid or potash dissolves the lime completely and this consequently is
entirely separated from the hides and remains in the bath.
A solution found to be very advantageous is composed of 3 litres of sulphuric
acid, of 66° Bé. and 300 litres of water. This quantity suffices for at least 20 cow
hides. For the potash solution a strength of 2° Bé. has proved advantageous.
The above mentioned solution, given by way of example, suffices completely
for the purpose of removing the lime from the hides. But acid and potash
solutions may be used together.
The process with potash is particularly suitable for upper leathers, as the potash
keeps the leather softer, whereas for sole leathers the use of acid is advisable, as
the leather is rendered harder thereby.
After completion of the process, the hides can with advantage be placed for
some hours in water, for removing impurities; but this has no influence on the
process under consideration.
The advantages of the new process as compared with the existing methods of
operating are very considerable; in the first place, much time is saved in the
manufacture of the leather, and the process is consequently cheapened.
An example will shew this:
In order to free 25 cowhides from lime according to the old method the operator
required on an average two days. The wages amount on an average to about

page_text: 4 shillings a day, causing an expense of 8 shillings for 25 hides. According to the
improved process on the other hand one operator can free 25 hides entirely from
lime in about one hour, the cost for wages and materials used not exceeding about
2 shillings, so that about 6 shillings are saved on every 25 hides as compared
with the old process.
When dealing with large quantities and with economical
treatment, the saving may be comparatively greater.
But also the quality of the leather is better by the new process. With the stone
and the knife the line cannot be completely removed notwithstanding the most
perfect workmanship, as these instruments do not penetrate into the interior of the
pores.
The lime consequently remains in these, and the leather becomes more or less
hard and brittle.
The solution on the other hand can penetrate and act everywhere, so that no
trace of lime remains in the hides. In addition, the improved process also obviates
the disadvantage, occurring with the treatment with stone and knife, that by these
instruments even with the most careful workmanship the hides become scratched
or otherwise damaged; for example the grain or nerve of the leather is frequently
entirely destroyed which is entirely obviated by the new process.
Dated this 5th day of December 1895.
ABEL & IMRAY,
Agents for the Applicant.
Process for the Removal of Lime from Hides and Skins after
Treatment in the Lime Bath.
I, ADOLPHE BROGARD of Mörchingen, Lothringen, Germany, Tanner, 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 :-
The preparation of hides and skins for tanning commences, as is well known, by
placing the same, after washing in water, for a certain time in a lime bath in
which they swell, so that after removal from the bath they can be readily freed
from the hairs and fleshy or mucous constituents by scraping with a knife. When
this has been done, it is necessary to remove from the bides or skins the adhering
lime particles which would otherwise soon render them hard and brittle. This has
heretofore been done by placing the hides or skins in a revolving drum filled with
water, whereby the coarser particles of lime were removed. The hides and skins
were then placed on a block and scraped by means of a stone scraper, whereby the
lime was pressed out. As even by this means all the lime was not removed, the
hides were again scraped with a sharp knife.
During the scraping with the stone and the knife, the hide had to be repeatedly
dipped into water, because it became hard.
After this mechanical treatment the hides and skins were placed in the tan pit
for the tanning process.
The present invention has for its object to effect the removal of the lime from
the hides and skins in a more convenient, reliable and expeditious manner, and it
consists in subjecting them, after they have been taken out of the lime bath, and
the hairs &c. have been removed therefrom to the action of a dilute acid or potash
solution, in which they are left for a short time, say about two minutes, being
advantageously moved about during this time in order that all parts may come in
contact with the acid or potash solution.
The acid or potash dissolves the lime completely and this consequently is entirely
separated from the hides and remains in the bath.

page_text: A solution found to be very advantageous is composed of 3 litres of sulphuric
acid, of 66° Bé. and 300 litres of water. This quantity suffices for at least 20-
cow hides.
For the potash solution a strength of 2° Bé. has proved advantageous.
The above mentioned solution, given by way of example, suffices completely for
the purpose of removing the lime from the hides. But acid and potash solutions
may be used together.
The process with potash is particularly suitable for upper leathers, as the potash
keeps the leather softer, whereas for sole leathers the use of acid is advisable as
the leather is rendered harder thereby.
After completion of the process, the hides can with advantage be placed for some
hours in water, for removing impurities; but this has no influence on the process
under consideration.
The advantages of the new process as compared with the existing methods of
operating are very considerable; in the first place, much time is saved in the
manufacture of the leather, and the process is consequently cheapened.
An example will shew this:
in order to free 25 cowhides from lime according to the old method the operator
required on an average two days. The wages amount on an average to about
4 shillings a day, causing an expense of 8 shillings for 25 hides. According to the
improved process on the other hand one operator can free 25 hides entirely from
lime in about one hour, the cost for wages and materials used not exceeding about
2 shillings, so that about 6 shillings are saved on every 25 hides as compared with
the old process.
When dealing with large quantities and with economical
treatment, the saving may be comparatively greater.
But also the quality of the leather is better by the new process. With the
stone and the knife the lime cannot be completely removed notwithstanding the
most perfect workmanship, as these instruments do not penetrate into the interior
of the pores.
The lime consequently remains in these, and the leather becomes more or less
hard and brittle.
The solution on the other hand can penetrate and act everywhere, so that no
trace of lime remains in the hides. In addition, the improved process also obviates
the disadvantage, occurring with the treatment with stone and knife, that by these
instruments even with the most careful workmanship the hides become scratched or
otherwise damaged; for example the grain or nerve of the leather is frequently
entirely destroyed which is entirely obviated by the new process.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
Process for the removal of lime from hides and skins, consisting in treating the
same, after having been taken out of the lime, and having the hair and flesh
removed therefrom, with a sulphuric acid solution of about from 1.5 to 2 p.c..
strength during the space of about from 1 to 2 minutes, substantially as described.
Dated this 31st day of August 1896.
ABEL & IMRAY,
Agents for the Applicant.