Improvements in the Preparation of Leather."
Year: 1897

page_text: Date of Application, 28th Oct., 1897-Accepted, 24th Dec., 1897
66
COMPLETE SPECIFICATION.
Improvements in the Preparation of Leather."
I, HERMANN STREICH, of No. 2 Florentinsgraben Bonn on Rhine, in the German
Empire, Sadler, 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:―
By means of my invention leather may be tanned in a minimum time, and in a
very inexpensive manner which leather is particularly suited for harness,
apparatus and the like in which only one side of the leather is visible, and also
in the construction of strong but light articles, such for instance as leather trunks.
In carrying my invention into effect I place the raw, wet hides in an air tight
space, and leave them until the hair is easily removable. The hides are then placed
in pairs with the flesh side inwards and immersed in the tan pit, and left in the
same one or two days, so that the outsides are partially tanned The said hides
are then stretched in a frame and the outer side thereof covered over in some way
sufficiently to prevent the drying, whilst the flesh side is rubbed with a mixture
composed essentially of a solution of about 50 grammes of sugar in 15 grammes
of vinegar and 15 grammes of ammonia both of ordinary commercial strength
with addition of water if requisite for solution. After this mixture has penetrated
the hide as much as possible the same is allowed to become half dry, and the pre-
pared side is then covered with Turpentine varnish or Copal varnish whcich is then
allowed to become thoroughly dry. After this the hide is dyed, pressed and
stretched in a frame and dried.
The inventor is aware that solutions of sugar, ammonia and varnish or the like
have previously been used in the treatment of leather. The previous mode of
application of the said preparations, however, has been hitherto for another
purpose and effecting other results. Thus for instance, everyone acquainted with
the trade is aware that sugar or treacle has been applied in the preparation of
blacking in which case these materials serve principally to increase the glistening
effect. It is also well known that entirely tanned leather may be made heavier
by treatment with a sugar solution. Vinegar and ammonia have hitherto been
applied only for the removing of the lime and the swelling of the skins. Also oils
and fats have been hitherto used for the sole purpose of preserving the leather or
of making same pliant. It has further been known that leather may be made
water proof by means of varnish. The method of application hitherto in use, that
is to say, the application to finished hides, has, however, the drawback that the
varnish must be renewed from time to time, and that leather so treated increases
considerably in weight, both in consequence of the previous complete tanning as
also in consequence of the repeated coats of varnish. My invention, however,
effects neither a making pliable of the leather, nor an increase of the glistening
effect by means of polish, nor yet an increase of the weight. Moreover, there can
be no question of unliming the leather by means of the vinegar and ammonia
because the hides are only lightly tanned in the tan pit and an unliming does not
take place. But my process effects a great improvement in the leather in its
strength and power of resistance to outer influences. It protects the same from

page_text: crumpling up or blistering, and enables its weight to be considerably reduced.
All this is effected by the addition of sugar dissolved in vinegar and ammonia and
by the subsequent single coat of varnish, whereas in the present system the same
result is very imperfectly attained. Thus for instance in the manufacture of
leather trunks it is necessary to line the walls with cardboard causing extra cost,
loss of time, and increased weight. The vinegar and ammonia are chiefly made
use of because the hides after treatment with these substances can be much more
easily, better, and more clearly dyed. The power of resistance against damp is
proved by experiment to be attributable to the treatment with sugar solution,
because the coat of varnish alone does not afford the required power of resistance
to damp. The preservation of the leather is consequently much better than that
obtained by the usual method.
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:
The improved process of preserving leather characterized by the treatment of
hides partially tanned on the outside with a solution of sugar in vinegar and
ammonia applied to the flesh side thereof with a subsequent coat of varnish, sub-
stantially as described.
300
Dated the 28th day of October 1891.
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C. Patent Agents for the Applicant.