Improvements in and relating to the means used for the Bating of Hides and Skins.
Year: 1898

page_text: Date of Application, 4th June, 1898-Accepted, 23rd July, 1898
COMPLETE SPECIFICATION.
Improvements in and relating to the means used for the Bating of
Hides and Skins.
JOSEPH TURNEY WOOD, of 29, Musters Road, W.B., Nottingham, Leather Dresser,
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 has reference to improvements in and relating to the means,
liquid, or bate used for the bating or pureing of hides and skins previous to the
process of tanning the same.
At the present time skins are usually bated by means of a liquid or bate prepared
from dog or pigeon dung, and although the bating action or actions have not
hitherto being thoroughly understood, it is a well known fact that fermentations
going on in the dung play an essential part. It was also pointed out in 1885 by
H. R. Proctor in his Text Book on Tanning that the action of the bate was in a
great measure due to bacteria. It is also a known fact to practical tanners that
a dung bate, properly applied produces the best quality of leather.
Owing however to the varying composition of the dung used the bate made there-
from possesses varying properties, its bating action is uncertain, its properties are
readily affected by atmospheric influences, and the skins treated are liable to
putrefaction.
As a substitute for dung bate it has been proposed, as set forth in the Specification
of Patent No. 21720 A.D. 1895, to use a bate made from a pure culture of bacteria.
Such bate however does not possess all the essential properties of a dung bate, and
although bacterial action is necessary such action alone is not sufficient as was
pointed out by the present inventor in 1894 in the Journal of the Society of
Chemical Industry.
The present inventor has now discovered that the bating action of a dung
bate is due to the combined action of enzymes or unorganised ferments, and to
certain amine compounds in the dung. These compounds consist of amines
(i.e. ammonia in which one or more atoms of hydrogen has or have been replaced
by alcohol radicles) in combination with lactic acetic, and other organic acids
contained in the dung, the acids named being the principal ones.
The present inventor has also discovered that the bating action of the enzymes
alone, or the action of the chemical compounds alone are inefficient, and that the
enzymes exert their bating action in the presence of the chemical compounds,
while these latter in addition have an independent action.
The object of this invention is the production according to scientific methods of
a bate having similar properties to those of a dung bate, such properties in the
improved bate being defined and definite, but capable of being modified according
to the requirements of the skins to be bated and the leather to be produced.
According to this invention the liquid or bate is made by producing by
fermentation an enzyme or enzymes of the same character as the enzymes con-
tained in dog dung or produced from bacteria obtained from dung, and to the
liquid thus obtained there is added an organic acid and an alkali.

page_text: The inventor has discovered that for an efficient bate a pure culture of bacteria
is insufficient, and that no single organism hitherto isolated will give results equal
to dung. He has also discovered that the production of these enzymes depends
more upon the composition of the nutrient medium in which the bacteria are
cultivated than upon the kind of bacteria, although these latter must be capable
of producing the required enzymes, the production of which appears to be due
to a symbiotic growth of bacteria, at present little understood.
It is desireable that the nutrient medium should be without sugars or starchy
matters, and although the composition of the nutrient medium may be varied good
results can be obtained according to ordinary bacteriological methods by using
a medium composed of.
This medium is maintained at a temperature of about 37° C. (the most favour-
able temperature for the fermentation) until the required bacterial action is com-
pleted, the time necessary being about seven days, and to each litre of the liquid
thus obtained there is added from two to six grammes of lactic acid.
Acetic or
other similar organic acid may be used instead of the lactic acid, but sulphuric or
mineral acids must not be used. The acid liquid is afterwards neutralized by
ammonia which is added when the bate is to be used, and there is then formed
certain chemical compounds similar to those found in a dung bate.
The addition of the acid to the nutrient medium will immediately stop the
growth of bacteria, but the acid is not added for that particular reason, but for
the particular purpose set forth.
Instead of the enzymes obtained from the bacteria of dung, other enzymes of
a similar character may be used, such as the enzymes obtained from the bacteria
found on skins during the sweating process.
For bating skins in a practical manner with the improved bate herein set forth,
the method of using the same is preferably varied according to the skins to be
treated and the kind of leather it is required to produce. Thus for kid skins,
skivers, and other skins for which dog dung has hitherto been used, the skins after
the liming process are first well washed in water in the usual way to remove the
bulk of the lime. The skins are then placed in a wheel or paddle with the bate
prepared as before described with the acid exactly neutralized by the ammonia or
so nearly neutralized that the alkaline action of the skins will complete the
neutralization, all skins being alkaline when introduced into the bate.
33
con-
The bate is diluted according to the amount of liming the skins have undergone
and when in the paddle or wheel the skins and the bate are maintained at a
temperature of about 37° C. and the skins paddled until they have "fallen
siderably. The skins are then removed from the wheel or paddle and scudded
preferably on the "grain" side, after which they are returned to the wheel or
paddle and the paddling continued until the bating action is completed, this being
judged in the usual way by a practical tanner according to the feel of the skins.
The strength of the bate after the scudding process may be varied if found
desireable.
After the bating process is completed the skins are treated in the usual manner.
When the improved bate is to be used for light hides and similar skins which
have hitherto been treated with pigeon dung, the skins after the liming process are
washed in the usual manner, heated to a temperature of about 37° C. and placed in
a wheel or paddle containing by preference the improved bate in an acid condition,
that is before the ammonia has been added, the bate being previously diluted
according to the amounts of liming the skins have undergone. The skins are then
paddled until the tanner by the feel judges that the whole of the lime has been
removed. The acid bate is then neutralized by ammonia, with or without removing

page_text: the skins, and the paddling is continued until the bating process is completed,
this being judged of by the feel of the skins.
The bated skins are then scudded washed, and treated in the usual manner.
The strength of the bate into which the skins are placed for both methods is
varied according to the amount of liming the skins have undergone, that is to
say for "high" limed skins a stronger bate is required than for skins which have
been subjected to a moderate liming.
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. A bate having the essential properties of a natural dung bate but prepared
according to scientific methods from the means and in the manner substantially as
set forth in the accompanying specification.
2. The bate described and set forth in the accompanying specification.