An Improved Process for the Preparation of Skins.
Year: 1898

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Date of Application, 31st May, 1898-Accepted, 22nd Oct., 1898
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COMPLETE SPECIFICATION.
An Improved Process for the Preparation of Skins.
1.
I FELIX GROGNET, of 6, Boulevard Nanterre, Department of Seine, 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:-
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As soon as the fresh skins reach the preparers, the procedure is to stretch them
very strongly, the derma or chorion upmost, upon cross-pieces arranged in the
form of a St. Andrew's cross, and then to spread over them, upon the side on
which the derma is, a somewhat thick layer, of from 2 to 3 centimetres or more,
of powders which have been previously prepared in any desired quantities.
This mixture is composed of three products, that is to say:
1. One third of powdered yellow clay also known as collyrite clay which is a
silicate of hydrated alumina and of silica frequently containing foreign matter
and is a clay of very fine grain, absorbing water very readily.
2. One third of talc or Briancon chalk, and
3. One third of protoxide of barium or baryta.
The whole being calculated upon the respective weights of these powders, and
being well mixed.
A ventilator or aspirator of any suitable kind is then employed, being actuated
by an engine of sufficient power for obtaining in all parts the displacement indi-
cated below:-
The first three days the speed of the air should be that of a gentle breeze or
about seven metres per second, and subsequently more or less according as the
surrounding air is more or less saturated with moisture.
If everything has been properly carried out, the skins will have become finally
extra imputrescible within fifteen days, even those intended for tanning; this
operation is also sufficient for those intended for furriery and so forth.
The skins are placed in a dry-air chamber for the purpose of destroying almost
completely by desiccation, and exactly within the period of time indicated above,
all the greasy or fleshy parts, in such a manner that they will disappear upon the
rubbing with the tool termed the fleshing-knife. This dry air chamber is indis-
pensable for the proper treatment of the skins.
It is not however indispensable that a ventilator or aspirator should be employed
in order to obtain a successful preparation of the skins, that is to say, to render
them imputrescible, but in this case the operation will be of greater or less
duration according to the condition of the atmosphere, and the frames should be
visited each day in order to judge when the skins have reached the imputrescible
state, which is the desideratum in all skin preservation, that state being indis-
pensable for all uses for which they may be intended.
The combination of the powders above mentioned may be varied almost
indefinitely by substituting for them their organic or inorganic equivalents which
are capable of preventing the decay of the products treated with them.
As a result of numerous experiments I have been led to the conclusion that
skins prepared by my process previous to tanning are impermeable by moisture