A PROCESS FOR BLEACHING VEGETABLE TEXTILE FABRICS to be as follows:
Year: 1885

page_text: I, WILLIAM MATHER of Salford Iron Works, Manchester in the county of
Lancaster, Engineer, do hereby declare the nature of my invention for "A PROCESS
FOR BLEACHING VEGETABLE TEXTILE FABRICS to be as follows:-
"
In the operations of bleaching vegetable textile fabrics hitherto employed, the
fabric is first boiled in vessels, commonly called kiers, with a solution of lime for
a considerable number of hours. It is then removed from the vessels and very
thoroughly washed and further treated with acid in order to remove all traces of
lime after which a second very thorough washing is required to remove all traces
of the acid. The liming is apt to produce stains which though not visible when
formed, frequently appear in the subsequent operations of dyeing, printing and
finishing, forming a continual source of anxiety and loss. The quantity of water
required for this first stage in bleaching is very considerable and many unsuccessful
efforts have been made to dispense with the liming operation and the laborious and
costly cleansing which is necessary after it, and before the next operation can be
cominenced. In continuing the bleaching, the cloth is boiled for many hours in a
solution of soda ash or soda ash with resin in a kier from which the fabric is
again removed and washed in cold water. Lighter qualities of cloth are then
treated with solutions of chloride of lime and acids with intermediate and sub-
sequent washings to produce the required whiteness; or more frequently in order
to secure a thorough "bottoming" of the fibre, a third boiling in a solution of an
alkali is employed with further washing in cold water, and finally the treatment
with chloride of lime and acid is applied. Several days are required for these
operations, the greater part of the time being occupied in the alkali treatment.
The successive operations of boiling in hot solution and immediately cooling down
the cloth in the many washings necessary between the boilings cause the fibres to
become closed after having been opened by the action of high temperature and
increase the difficulty of cleansing.
The quantity of water required is also very great, especially after the lime
boiling and this fact has prevented bleaching being carried on hitherto commer-
cially in any locality not possessing a constant and enormous supply of pure
water..
Further, the vegetable fibre suffers both in strength and weight in the ordinary
alkali process,—firstly from the action of the lime and secondly from the tension

page_text: to which it is subjected in its frequent transference to and from the boiling vessels
and in its passage through the washing machines.
Although it has long been known that caustic soda possesses valuable properties
as a bleaching agent, the danger of rendering the fibre tender by its use has
hitherto prevented this agent from being practically and safely employed.
My invention relates to a process in which I make exclusive use of this agent in
the alkali treatment in bleaching instead of the lime, soda-ash and resin as above
stated; and in which I dispense with all washing of the fabric from its grey state
up to that stage when the acid treatment begins namely the whiting operations
with chloride of lime and acid. My process also renders unnecessary the acid
treatment between two successive alkali treatments as for instance between
boiling in lime and boiling in soda-ash, and it enables me to maintain the high
temperature of the cloth from the grey state to the stage when the acid treatment
begins.
For this purpose I saturate the grey fabric with hot solution of caustic soda at
about 6° Twaddell and deposit it either in the state of a rope or in its full width
into waggons which are run into a chamber through a suitable door that can be
closed steam tight. In these waggons the fabric is laid in such a manner that all
parts of it can be thoroughly saturated with liquid and permeated by steam.
Instead of first saturating the fabric with caustic soda, it may in the first place be
laid in the waggons as described and when these are run into the chamber, the
saturation of the fabric may be effected therein by filling the chamber with hot
solution of caustic soda and circulating it therein. After saturation is effected, the
solution is run out of the chamber and steam of low pressure is then admitted to
act on the saturated fabric in the waggons. After about an hour the liquor that
drains from the fabric is discharged from the bottom of the chamber and a fresh
supply of solution of caustic soda is sprinkled from the roof of the chamber all over
the fabric so that the requisite degree of saturation is maintained in the presence
of the steam. The amount of liquor sprinkled on the fabric must not be so great
as to submerge any portion of it as this would impede the action of the steam but
it should be sufficient to prevent the steam from parching or drying the fabric.
After a short interval the drainage from the sprinkled fabric is discharged from
the chamber and the fabric is again sprinkled with hot solution of caustic soda.
The quantity of liquor sprinkled each time varies with the weight and texture of
the fabric, but I find about 20 gallons per ton of cloth sufficient.
These operations of sprinkling and discharging the drainage of caustic soda are
repeated at intervals of about an hour while the fabric remains exposed to the
action of the steam.
Instead of thus sprinkling at intervals a continuous sprinkling may be main-
tained by a pump arranged to withdraw the drainage of liquor from the lower
part of the vessel and to eject it through sprinkling nozzles at the upper part.
Or there may be a continuous or intermittent supply of the sprinkling liquor
from an elevated cistern.
When the drainage liquor is discharged it may be collected in a tank to settle,
and it may, filtered, if necessary, be used again for first saturation of fabric.
Usually five hours of this treatment suffice to thoroughly "bottom" and remove
from the fabric all substances that can be removed by alkali treatment such as the
natural mordants that might afterwards interfere with dyeing. For heavy cotton
cloths and linen the operation should be continued, as may be determined by
experience for a few hours more. After the caustic soda treatment the chamber
is filled or partially filled with boiling water which is made to circulate rapidly
through the fabric. The waggons are so arranged that the circulating water.is
made to percolate in all directions through the mass of fabric. The hot water may
be entirely discharged and renewed from time to time or a continuous stream of
fresh hot water may be supplied while a like quantity of water is discharged..
The temperature of the water is maintained in the chamber by means of a
steam pipe.
L..

page_text: The duration of this washing is readily determined by observing the condition
of the effluent. The quantity of water required for this washing operation is
much less than that required in an ordinary washing-machine for one washing
with cold water.
For example, in the ordinary treatment, from 20,000 to 30,000 gallons of water
are required for each ton of fabric, whereas in the process which I have described
about 3,000 or at most 5,000 gallons suffice for the whole treatment. This economy
of water is probably in great measure owing to the fact that as it washes out the
caustic soda from the fabric it acts itself as a solution of caustic soda which while
it becomes gradually more and more diluted is nevertheless a powerful cleansing
agent.
The application of the hot water as described prevents any of the caustic soda
from remaining in the fabric when it is again exposed to the atmosphere.
When the waggons are drawn out of the chamber, the fabric after a single
rinsing in cold water may be introduced at once into the solution of chloride
of lime.
In treating fabrics by the process above described there is no danger of rendering
the fibres weak or tender, as thorough "bottoming" is effected by one agent in.
a single continuous operation carried on without handling or disturbing the
material without any intermediate washings or violent changes of temperature.
I am aware that in the bleaching of yarns, they have been boiled in a solution
of soda-ash and washed in the same vessel; but this is injurious to the fibre and
is not applicable to woven fabrics.

page_text: A Process for Bleaching Vegetable Textile Fabrics.
I, WILLIAM MATHER of Salford Iron Works, Manchester in the County of
Lancaster, Engineer do hereby declare the nature of my said invention and in
what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :-
In the operations of bleaching vegetable textile fabrics hitherto employed, the
fabric is first boiled in vessels, commonly called kiers, with a solution of lime, for
a considerable number of hours. It is then removed from the vessels and very
thoroughly washed and further treated with acid in order to remove all traces of
lime, after which a second very thorough washing is required to remove all traces
of the acid. The liming is apt to produce stains which, though not visible when
formed, frequently appear in the subsequent operations of dyeing, printing and
finishing, forming a continual source of anxiety and loss. The quantity of water
required for this this first stage in bleaching is very considerable, and many
unsuccessful efforts have been made to dispense with the liming operation and the
laborious and costly cleansing which is necessary after it, and before the next
operation can be commenced. In continuing the bleaching, the cloth is boiled for
many hours in a solution of soda ash or soda ash with resin in a kier, from which
the fabric is again removed and washed in cold water. Lighter qualities of cloth
are then treated with solutions of chloride of lime and acids, with intermediate
and subsequent washings, to produce the required whiteness; or, more frequently,
in order to secure a through "bottoming" of the fibre, a third boiling in an
alkaline solution is employed with further washing in cold water; and finally the
treatment with chloride of lime and acid is applied. Several days are required
for these operations, the greater part of the time being occupied in the alkali
treatment. The successive operations of boiling in hot solution and immediately
cooling down the cloth, and the many washings necessary between the boilings
cause the fibres to become closed after having been opened by the action of high
temperature and increase the difficulty of cleansing. The quantity of water
required is also very great, especially after the lime boiling, and this fact has
prevented bleaching from being carried on hitherto commercially in any locality
not possessing a constant and enormous supply of pure water. Further, the
vegetable fibre suffers both in strength and weight in the ordinary alkali process,-
first from the action of the lime, and secondly from the tension to which it is
subjected in its frequent transference to and from the boiling vessels, and in its
passage through the washing machines.
Although it has long been known that caustic soda possesses valuable pro-
perties as a bleaching agent, the danger of rendering the fibre tender by its use has
hitherto prevented this agent from being practically and safely employed.
My Invention relates to a process in which I use this agent in the alkali
treatment in bleaching instead of the lime, soda-ash and resin as above stated;
and in which I dispense with all washing of the fabric from its grey state up to
that stage when the acid treatment begins, namely the whiting operations with

page_text: chloride of lime and acid. My process also renders unnecessary the acid treatment
between two successive alkali treatments, as for instance between boiling in lime
and boiling in soda-ash, and it enables me to maintain the high temperature of the
cloth from the grey stage to the stage when the said treatment begins.
For this purpose, I saturate the grey fabric, after preliminary cleansing, with hot
solution of caustic soda, which may be at about from 1° to 4° Twaddell, and
I deposit it, either in the state of n rope, or in its full width, into waggons which
are run into a chamber through a suitable door that can be closed steam tight.
In these waggons the fabric is laid in such a manner that all parts of it can be
thoroughly saturated with liquid and permeated by steam. Instead of first
saturating the fabric with caustic soda, it may in the first place be laid in the
waggons as described and, when these are run into the chamber, the saturation of
the fabric may be effected therein by filling the chamber with hot solution of
caustic soda and circulating it therein. After saturation is effected, the solution is
run out of the chamber, and steam, which need not have a pressure exceeding 15¹b,
is then admitted to act on the saturated fabric in the waggons.
After about an
hour the liquor that drains from the fabric is discharged from the bottom of the
chamber, and a fresh supply of solution of caustic soda is sprinkled from the roof
of the chamber all over the fabric, so that the requisite degree of saturation is
maintained in the presence of the steam. The amount of liquor sprinkled on the
fabric should not be so great as to submerge any portion of it, as this would impede
the action of the stean, but it should be sufficient to prevent the steam from
parching or drying the fabric. After a short interval the drainage from the
sprinkled fabric is discharged from the chamber, and the fabric is again sprinkled
with hot solution of caustic soda. The quantity of liquor sprinkled each time
varies with the weight and texture of the fabric, but I find about 20 gallons
per ton of cloth sufficient. These operations of sprinkling and discharging the
drainage of caustic soda are repeated at intervals of about an hour, while the
fabric remains exposed to the action of the steam. Instead of thus sprinkling
at intervals, a continuous sprinkling may be maintained by a pump arranged to
withdraw the drainage of the liquor from the lower part of the chamber and to
eject it through sprinkling nozzles at the upper part. Or there may be a con-
tinuous or intermittent supply of the sprinkling liquor from an elevated cistern.
When the drainage liquor is discharged, it may be collected in a tank to settle,
and it may be filtered and concentrated if necessary to be used again for the
preliminary cleansing or the first saturation of fabric. Usually five hours of this
treatment suffice to thoroughly "bottom" and remove from the fabric all sub-
stances that can be removed by alkali treatment, such as the natural mordants
that might afterwards interfere with dyeing. For heavy cotton cloths and linen,
the operation should be continued for a few hours more or repeated as may
afterwards be determined by experience.
After the caustic soda treatment the chamber is filled, or partially filled with
boiling water or a weak alkaline solution which is made to circulate rapidly
through the fabric. The waggons are so arranged that the circulating water is
made to percolate in all directions through the mass of fabric. The hot water or
solution may be entirely discharged and renewed from time to time, or a continuous
stream of fresh hot liquor may be supplied while a like quantity is discharged.
The temperature of the liquor is maintained in the chamber by means of a
steam pipe.
The duration of this washing, which should be finished with pure water, is
readily determined by observing the condition of the effluent. The quantity of
water required for this washing operation is much less than that required in an
ordinary washing-machine for one washing with cold water.
For example, in the ordinary treatment, from 20,000 to 30,000 gallons of water
are required for each ton of fabric, whereas, in the process which I have described,
about 3000 or at most 5000 gallons suffice for the whole treatment. This economy
of water is probably in great measure owing to the fact that, as it washes out

page_text: the caustic soda from the fabric, it acts itself as a solution of caustic soda which,
while it becomes gradually more and more diluted, is nevertheless a powerful
cleansing agent. The application of the hot water as described prevents any of
the caustic soda from remaining in the fabric when it is again exposed to the
atmosphere.
When the waggons are drawn out of the chamber, the fabric, after a single
rinsing in cold water, may be introduced at once into the solution of chloride of
lime.
In treating fabrics by the process above described, there is no danger of ren-
dering the fibres weak or tender, as thorough "bottoming" is effected substantially
by one agent in a single continuous operation, carried on without handling or
disturbing the material, without any intermediate washings or violent changes of
temperature.
I am aware that, in the bleaching of yarns, they have been boiled in a solution
of soda-ash and washed in the same vessel; but this is more or less injurious to the
fibre and is not conveniently applicable to woven fabrics, I therefore make no claim
to such treatment, but,
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 herein described process for effecting the alkali treatment in the bleaching
of vegetable textile fabrics, that is to say, loading them in lattice trucks which
are run into a closed chamber, and while they remain therein, without removal or
manipulation, and without intermediate washings, subjecting them, while they are
kept saturated with hot solution of caustic soda, to the action of steam; and
finally washing them by circulation of hot water through them, thus preparing
them for the ordinary chlorine and acid treatment.