An Improved Process for Retting, Cleansing, and Deoxidising Textile Fibres.
Year: 1893

page_text: Date of Application, 17th Feb., 1893-Accepted, 18th Mar., 1893
COMPLETE SPECIFICATION.
An Improved Process for Retting, Cleansing, and Deoxidising
Textile Fibres.
I, ALFRED GRUSCHWITZ of Neusalz on the Oder, in the German Empire,
Factory Proprietor, 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 :-
Various methods have been devised for superseding the retting of textile fibres
by dew and water but all have proved to be faulty in that, the opening out of the
pectinates (isolation of the fibres) is insufficient, the fibres being or remaining
uncleansed, rendering it necessary to subject the fibres in the form of yarn or cloth
to a series of troublesome and injurious bleaching operations, or in that, during the
isolating process the agents employed therein, acids for instance, are not entirely
removed consequently soon rendering the fibres liable to fracture. To the first
category belong the methods of Lefébure (hot alkaline baths), Schenk (warm
water), Parry (high pressure steam); to the second, those of Poole (lime, dilute
sulphuric acid), Dupré (boiling with a watery solution of muriatic acid) and
others.
The process of this invention for retting, cleansing, and deoxidising or freeing
from acid, textile fibres such as flax, hemp, nettle, china grass, etcetera, as dis-
tinguished from those hitherto employed, consists in opening out the pectinates by
means of a very dilute solution of sulphuric acid in a rarefied space at, at the
highest, a temperature of 90° Celsius which object is in this way thoroughly
accomplished without injury to the fibres which are then subjected to an alkaline
bath also in a rarefied space or vacuum for the purpose of thoroughly removing
the acid.
The process is carried out in the following manner :-)
-The stalks either quite
raw or carefully crushed by mechanical means to open out the same are placed in
lead lined steam boiling pans provided with a steam worm for the purpose. The
previously heated dilute sulphuric acid, in quantity up to 5 per cent. of the weight
of the material under treatment, is passed into the same and a vacuum then pro-
duced therein. The contents of the pan or pans are then heated to a temperature
not exceeding 90° Celsius during about four hours. The vacuum is then terminated
and the acid bath replaced by an alkaline bath also in a vacuum and finally the
material washed at a warm temperature.
In this process three important reactions take place:
1. The removal of the pectinate covering enclosing the fibres by the action of the
acid bath and of the subsequent alkaline washing.
2. The removal or separation of the fibres under a vacuum in which way only is
this practicable by reason of the capillary structure of the fibres.
3. The particular cleansing process for the isolated fibres which it is then only
necessary to subject to very gentle operations, analogous to those for cotton, to
render them quite white.
By the novel employment of a vacuum for bringing about a thorough penetration
of the acid and also and not less so of the alkaline liquid binding the acid, it is
practicable to perform the process not only very quickly but also without injuriously
affecting the durability of the fibres because the temperature at which the process
is performed is always considerably below 100° Celsius.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is
A process for the retting, cleansing and freeing from acid of textile fibres such

page_text: as those referred to, consisting in decomposing the vegetable glue by means of dilute
sulphuric acid and then removing the acid from the fibres each operation being
performed in a vacuum pan at a temperature under 100° Celsius, substantially as
described and shewn.
Dated this 17th day of February 1893.
CAPITAINE & VON HERTLING,
89, Chancery Lane, London, W.C., Agents for the Applicant.