Improvements in or relating to Tanning.
Year: 1896

page_text: Date of Application, 13th May, 1896
Complete Specification Left, 24th Dec., 1896-Accepted, 13th Feb., 1897
Improvements in or relating to Tanning.
I, ALEXANDRE LEVINSTEIN, of 29 Avenue Wagram, Paris, in the Republic
of France, Engineer, do hereby declare the nature of this invention to be as
follows:-
The ultra-rapid tanning processes with fulling vats, especially with very strong
extracts, have not hitherto given satisfactory results, because nobody had a clear
idea of the very important part played by the temperature in such tanning
processes.
The temperature must not be too high because the leather obtained would be
brittle, of bad quality and of bad colour.
It has been attempted, it is true, to avoid excesses of the temperature by stopping
the fulling vat in order to let the temperature fall to a suitable degree. But by
avoiding the drawback caused by excess of temperature, another worse drawback
has been created, since the operation becomes irregular, and the production of
leather is diminished, the time during which the vat is stopped being time lost for
tanuing.
The temperature must not be too low, either, because then the tanning goes on
very slowly, which is the opposite of the end to be attained, and the leather has in
consequence to remain in the vat much longer.
It is therefore most important to be able to vary the temperature in the interior
of the fulling vat as desired and to be able to bring it at any time to a degree
suitable for obtaining leather of good quality and colour.
For this purpose I have devised the following means.
1) If the temperature in the vat at the beginning of tanning operation is too
low or if it fall too low during the operation, steam is sent into the vat by means of
a suitably arranged apparatus and so the temperature is immediately brought to
any desired degree.
It is very important to be able to raise the temperature in the vat immediately
at the beginning of tanning to a desired degree, as the swelling and tanning of
hides takes place better and especially quicker at a temperature between about
20 and 40° C. (according to the nature of leather to be tanned), than at a lower
temperature. To arrive at such desired temperature simply by the rotation of the
vat, especially when the outside temperature is low, requires a long time, which is
of course undesirable, when the main purpose is to obtain quick tanning, whereas
by the introduction of steam in the vat the suitable temperature is immediately
obtained.
Another advantage of using steam is the following: There is no necessity to
rotate the vat quickly, if it is desired to raise the temperature; the vat can have a
slow movement, which is extremely advantageous for avoiding wearing off of the
grainside of the leather being tanned.
2) If the temperature becomes too high air is blown into the vat by means of a
suitable ventilator, whereby the inner temperature of the vat is lowered.
3) I arrange on the driving shaft of the fulling vat any device enabling the
speed of the vat to be varied as desired.

page_text: As an example, I will assume that the fulling vat is driven by belting: it is
sufficient in that case to have a series of conical pulleys so as to cause the belt to
pass from one cone on to the other by operating a disengaging mechanism.
If on the contrary the vat is driven by electricity, it is sufficient to insert a
variable resistance in order to regulate the speed of the dynamo.
By such means it is possible to quickly regulate the inner temperature of the
vat and to bring it immediately to the desired degree at the beginning of the
operation and to maintain it in desired limits during the operation so as to obtain
the best results without stopping the vat.
Dated this 13th day of Mov 1806
BOULT & WADE,
Agents for the Applicant.
Improvements in or relating to Tanning.
1, ALEXANDRE LEVINSTEIN, of 29 Avenue Wagram, Paris in the Republic of
France, Engineer, 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 very rapid tanning processes with fulling vats, especially with very strong
extracts, have not hitherto given satisfactory results, because the very important
part played by the temperature in such tanning processes has not been recognised.
The temperature must not be too high or the leather obtained would be brittle,
of bad quality and of bad colour.
It has been attempted, it is true, to avoid excesses of the temperature by stopping
the fulling vat in order to let the temperature fall to a suitable degree. But by
thus avoiding the drawback caused by excess of temperature, another and worse
drawback has been created since the operation becomes irregular, and the produc-
tion of leather is diminished the time during which the vat is stopped being time
lost for tanning.
The temperature must not be too low, either, because then the tanning proceeds
very slowly, which is the opposite of the end to be attained, and the leather has in
consequence to remain in the vat much longer.
It is therefore most important to be able to vary the temperature in the interior
of the fulling vat as desired and to be able to bring it at any time to a degree
suitable for obtaining leather of good quality and colour.
For this purpose I have devised the following method of procedure.
1. If the temperature in the vat at the beginning of the tanning operation is too
low, or if it fall too low during the operation, steam is introduced into the vat by
means of any suitably arranged apparatus and so the temperature is brought to any
desired degree.
It is very important to be able to raise the temperature in the vat immediately
at the commencement of tanning, to a desired degree, as the swelling and tanning
of bides takes place better and quicker at a temperature between about 20 and
40° C. (according to the nature of the leather to be tanned), than at a lower
temperature. To arrive at such desired temperature simply by the rotation of the
vat, especially when the outside temperature is low, takes a long time, which is of
course undesirable, when the main purpose is to obtain quick tanning, whereas
by the introduction of steam into the vat the desired temperature is immediately
obtained.
Another advantage of using steam is that there is no necessity to rotate the vat
quickly, if it is desired to raise the temperature; the vat can have a slow movement,

page_text: which is extremely advantageous for avoiding the wearing or rubbing away of the
grainside of the leather being tanned.
2. If the temperature becomes too high air is blown into the vat by means
of a suitable ventilator or injector, whereby the inner temperature of the vat is
lowered.
3. Further the shaft of the fulling vat may be so driven that the speed of
rotation of the vat may be varied as desired.
As an example I will assume that the fulling vat is driven by belting; it is
sufficient in that case to have a series of conical pulleys so as to cause the belt to
pass from one cone on to the other by operating a disengaging or belt shifting
mechanism.
If on the contrary the vat is driven by electricity, it is sufficient to insert in the
circuit a variable resistance in order to regulate the speed of the dynamo.
By such means it is possible to quickly regulate the inner temperature of the
vat and to bring it immediately to the desired degree at the beginning of the
operation and to maintain it within desired limits during the operation so as to
obtain the best results without stopping the vat.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is ;-
1. In tanning skins and the like varying or regulating the temperature in the
fulling vat by the introduction of air or steam or by varying the speed of revolution
of the vat substantially as described.
amber 1906
BOULT & WADE,
Agents for the Applicant.