Improvements in Processes for Bleaching or Dyeing Spanish Cane (Calamus Rotang), Bamboo, and other Plants which have a Siliceous Coating.
Year: 1898

page_text: Date of Application, 4th Apr., 1898-Accepted, 28th May, 1898
COMPLETE SPECIFICATION.
Improvements in Processes for Bleaching or Dyeing Spanish Cane
(Calamus Rotang), Bamboo, and other Plants which have a
Siliceous Coating.
I, RUDOLPH CARL WILHELM ALEXANDER SIEVERTS, of 26, Schwarzestrasse,
Hamburg, Germany, 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 this invention the cane either whole or split into strands and either free
from its siliceous coating or still covered therewith is first leached in a cold
condition with a dilute alkaline solution, such as a solution of caustic potash,
caustic soda, ammonia or a similarly acting solution. The action of the alkaline
solution may be facilitated by previously submitting the cane to a current of hot
steam and after this has had due effect upon the cane the latter is treated by
laying it in the cold alkaline solution. The cane thus treated is then submitted to
the action of an appropriate bleaching liquid for which it can be prepared if
necessary by a further exposure to a current of hot steam. According to the
nature of the alkaline material and the bleaching liquid selected either both may
be applied at the same time, or as stated above the bleaching may succeed the
leaching.
For example very good results are obtained by the simultaneous action of a
caustic potash solution of about 2 per cent. strength and of a solution of potassium
hypochlorite of about one per cent. strength. By another method leaching may
be first effected with a solution of ammonia of about 3 per cent. strength and the
cane may be then transferred to a bath of potassium hypochlorite. In both cases
the cane should be treated with sulphurous acid as a final step in the process.
The concentration of the liquors and the duration of the treatment are entirely
determined by the original colour and the diameter, that is to say the strength, of
the split or whole cane.
The novelty and chief characteristic of the present process consist in the
application of the alkali in a cold condition. While, as is known, a hot alkaline
solution dissolves the siliceous coating and on this account is used for stripping
this coating from the cane, a cold alkaline solution has practically no effect upon
the siliceous coating but leaves the cane in a condition in which it can be bleached
and dyed.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I declare that what I claim
is:-
(1) In a process for bleaching or dyeing Spanish cane (calamus rotang) bamboo
and other plants which have a siliceous coating, the method of leaching the cane
with a dilute alkaline solution in a cold condition with or without having first
exposed the said cane to a current of hot steam, and afterwards treating
the leached cane with an appropriate bleaching liquid with or without having
first exposed the said leached cane to a current of hot steam, substantially as
described.

page_text: (2) In a process such as is referred to in Claim 1, the method of simultaneously
applying the leaching and bleaching solutions to the cane, in a cold condition
substantially as described.
D
ABEL & IMRAY,
Agents for the Applicant.