An Improved Combined Tanning and Dyeing Process.
Year: 1899

page_text: Date of Application, 16th Sept., 1899
Canaloto Snocification Left 16th June, 1900-Accepted, 25th Aug. 1900
Date of Application, 16th Sept., 1899
Completo Specification Left 16th June, 1900-Accepted, 25th Aug.. 1900
PROVISIONAL SPECIFICATION.
An Improved Combined Tanning and Dyeing Process.
I, FRANZ WALTHER WARTENBERGER, of No. 11 near the Johanniskirche, Altona,
in the Empire of Germany, Tanner, do hereby declare the nature of this inven-
tion to be as follows:
The present invention relates to a process for the simultaneous tanning and
dyeing of skins, by introducing the dye-stuffs, such as aniline-colours, into the
tanning liquor, so that the tanning liquor as well as the dye-stuff may simul-
taneously act upon the properly prepared hides or skins.
A good working composition of tanning and dyeing liquor is obtained from
700 parts by weight of water, 10 parts by weight of picric acid, and 1 part by
weight of the desired aniline dye or colour.
The previously prepared skins are placed in this combined tanning and dye-
ing liquor and after the lapse of a few hours they are not only completely tanned
but also dyed by the dye or colour contained in the said liquor.
Practical experiments have proved that by this process an excellent colouring
of the tanned or dressed hides is effected which is accounted for by the fact that
the tanning liquor acts as a carrier for the dye and thereby enables the latter to
better and more evenly enter the pores of the grain of the skins than is possible
when, as hitherto, the dyeing thereof is done, after the completion of the tanning,
during the dressing of the skins.
The hides tanned and dyed according to the above process are preferably
submitted to a finish or final treatment which however does not form part of
this invention although for practical reasons it ought not to be omitted when
picric acid is used as tanning liquor.
This final treatment consists in drawing the tanned and dyed hides through
a bath composed of about 20 parts by weight of water, 4 parts of hypo-sulphite
of soda and 1 to 3 parts of hydrochloric acid.
The chemical process which takes place between the picric acid and hypo-
sulphite of soda may be explained in considering that picric acid is a substance
capable of being easily reduced and hypo-sulphite of soda a substance of high
oxidability which substances will act upon each other already when at low tem-
peratures and in diluted solutions. The superfluous picric acid present in the
tanning liquor becomes reduced thereby and is thus deprived of its discolouring
and poisonous qualities.
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1011
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Candombon 1900
HASELTINE, LAKE & CO.
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.

page_text: I, FRANZ WALTHER WARTENBERGER, of No. 11 near the Johanniskirche, Altona,
in the Empire of Germany, Tanner, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement:-
The present invention relates to the art of tanning and dyeing skins; and
it has for its object a process whereby the tanning and dyeing of skins may be
combined and effected simultaneously in a most expeditious and yet thorough
manner. With this end in view my improved process consists, first, in subjecting
the skins or hides which have been prepared for tanning by the usual liming
and bating processes, to the action of a weak aqueous solution of picric acid to
which the dye-stuffs, such as aniline colours, have been added, so that the picric
acid as well as the dye-stuffs may act simultaneously upon the skins, and, second,
in subjecting the thus simultaneously tanned and dyed hides or skins to the
action of a solution of hyposulphite of soda (Na, S₁ O₁₂+5H₂O) or other reagent
in order to fix not only the picric acid but also the colour. The tanned skins
being then finished for the market by beating, rubbing, scraping or the like, in
the usual manner. The essential feature of this invention lies therefore, in the
use of a highly diluted solution of picric acid into which is incorporated the dye-
stuff, that is to say, in the simultaneous application of picric acid and aniline,
and in the subsequent treatment with a suitable agent for fixing both the picric
acid and the colour in the simultaneously tanned and dyed hides.
The carrying into practice of my improved combined tanning and dyeing
process is very simple and the steps necessary to make a marketable leather are
as follows.
The hides of skins previously prepared by the usual liming and bating pro-
cesses are steeped in a combined tanning and dyeing solution, which may be
obtained from mixing about 700 parts by weight of water, 10 parts by weight
of pieric acid, and one part by weight of the desired aniline dye or colour, at
ordinary temperatures which in some cases may be raised to about 30° Centigrade
and maintained at this temperature during the tanning and dyeing process.
The duration of the latter depends upon the nature and weight of the hides and
varies accordingly from about 2 to about 4 hours. Practical experiments have
proved that by this operation not only a reliable tanning but also a most excellent
colouring of the hides is effected which is accounted for by the fact that the
picric acid solution acts at the same time as a carrier for the dye and thereby
enables the latter to better and more evenly enter the pores of the grain of the
skins, than is possible when the dyeing thereof is done separately after the com-
pletion of the tanning.
When the hides are thoroughly tanned and well dyed, they are removed from
the combined tanning and dyeing liquor and subjected to a subsequent treatment,
which consists in rinsing the tanned and dyed hides or leather proper in a
solution of about 20 parts of water about 4 parts of hyposulphite of soda
(Na,S,O, +5H,0) and about 1 to 3 parts of hydrochloric acid.
sulphite solution or other equivalent agent has the effect of fixing the picric
The hypo-
acid, of depriving the latter of its discolouring and poisonous properties and of
fixing the colour or dye applied to the leather by the above described combined
tanning and dyeing process. After this treatment the leather is washed and then
curried in the usual manner.

page_text: Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is —
1. The process, which consists in subjecting hides or skins previously prepared
for tanning by the usual processes, to the action of a combined tanning and
dyeing solution of about ten parts of picric acid, of about seven hundred parts
of water, and of about one part of aniline dye or colour, substantially as and for
the purpose set forth.
2. The process, which consists in subjecting hides or skins, previously prepared
for tanning by the usual processes, to the action of a weak solution of picric
acid to which an aniline dye or colour is added, and then to the action of a
solution of hyposulphite of soda and hydrochloric acid, substantially as and for
the purpose set forth.
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3. The improved combined tanning and dyeing process for simultaneously tan-
ning and dyeing hides or skins, substantially as herein before set forth.
Dated this 16th day of June 1900
.
HASELTINE, LAKE & CO.
45, Southampton Buildings, London, W.C., Agents for the Applicant.