An Improved Process for Dyeing Wool, and Apparatus for use in the same.
Year: 1890

page_text: Date of Application, 8th May, 1890
Complete Specification Left, 5th Feb., 1891-Accepted, 28th Mar., 1891
PROVISIONAL SPECIFICATION.
An Improved Process for Dyeing Wool, and Apparatus for use in
the same.
I, PAUL CAVAILLES, of 23, Boulevard de Strasbourg, Paris, in the Republic
of France, Cloth Manufacturer, do hereby declare the nature of this invention to
be as follows :-
This invention relates to a process of dyeing wool indigo, and apparatus for use
in the same.
Heretofore vats of indigo and sodium hydrosulphite have not been used for wool,
because they have been more expensive than fermenting vats. I have succeeded in
reudering their use practical and economical by the process which constitutes the
subject of the aforesaid invention.
I first prepare a concentrated vat which serves to keep the dye vats at the desired
strength according to the shades or tints to be obtained."
For preparing the said concentrated vat, I use for example 10 kilogrammes of
indigo reduced to a fine powder, with which I mix 10 litres of hot water at about
60 degrees, in order to properly moisten the indigo and then add 20 litres of thick
lime-milk containing from 6 to 7 kilogrammes of dry lime.
Into a zinc bucket I put 25 kilogrammes of sodium bisulphite at 30 degrees,
mix therewith from 2 to 3 kilogrammes of zinc powder according to the state of
oxidation of the powder, and agitate moderately for a few seconds. The liquid soon
becomes hot, and loses the orlour of sulphurous acid. Then I pour the hydrosulphite
obtained in this manner into the mixture of lime and indigo.
The whole preparation rapidly coagulates, in a few minutes the coagulation ceases,
the liquid is golden yellow, and is covered with a thick flower. The indigo is
reduced and dissolved.
It is expedient to use an abundant quantity of zinc powder in the preparation of
the hydrosulphite as above specified, in order that the reaction shall be effected in a
minute at most. The hydrosulphite becomes debased in contact with the air and
cannot be preserved.
I put in the dye vat a sufficient quantity of the reduced indigo from the concen-
trated vat for obtaining the desired tint in a single steeping operation.
For each fresh charge of wool indigo is introduced, and when the bath oxidizes
hydrosulphite prepared as above described is added.
In the case of deep tints when the bath contains much indigo, it is expedient to
squeeze the wool and expose it to the air on leaving the vat, whilst the liquid
squeezed out is caused to return to the vat, being brought as little as possible in
contact with the air. As the means ordinarily employed are quite inadequate for
fulfilling these various conditions I employ apparatus of special construction in
connection with the vat.
This apparatus, which is placed by the side of the vat comprises a frame carrying
two rollers the upper of which is pressed upon the lower by weighted levers acting
upon vertical rols that transmit the pressure to the bearings for the said upper
roller. In front of the two rollers is arranged an endless apron upon which the
wool taken from the dye bath is thrown. From this apron the wool passes between
the rollers and is freed by the pressure from the excess of dye which flows down
upon an inclined plane and returns to the vat. At the rear of the rollers is arranged
a fan for airing the wool in its passage from the rollers. This apparatus can if
desired be replaced by a hydroextractor of any construction adapted for drying and
airing the wool as soon as it leaves the vat.

page_text: The passage of the wool to the squeezing device presents the advantage of
ensuring the uniformity of the dye upon the wool.
To realize a still greater eronomy in the ease of baths which contain a great
quantity of indigo it is advisable to rinse the dyed wool in a small quantity of water
which takes up the indigo that is not fixed upon the wool. A second squeezing
device must in this ease be added to the rinsing bath. When this bath is sufficiently
concentrated it is caused to pass into the vat or is utilized in the precipitation of
the indigo.
The above-mentioned proportions used in the preparation of the several mixtures
depend to a great extent upon the nature of the indigo, bisulphite, zine, and other
substances and can be varicil.
It is necessary to avoid the employment of hydraulic lime.
Dated this 8th dow
Max 1800
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.
COMPLETE SPECIFICATION,
An Improved Process for Dyeing Wool, and Apparatus for use in
the same.
I, PAUL, CAN MILLÈS, of 23, Boulevard de Strasbourg, Paris, in the Republic of
France, Cloth Manufacturer, do hereby declare the nature of this invention, and in
what manner the same is to be performeil, to be particularly described and ascertained
in and by the following statement:-
This invention relates to a process of dyeing wool indigo and apparatus for use in
the same.
Heretofore vats of indigo and sodium hydrosulphite have not been used for wool,
because they have been more expensive than fermenting vats. I have succeeded in
rendering their use practical and economical by the process which constitutes the
subject of the aforesaid invention.
first prepare a concentrated vat which serves to keep the dye vat at the desired
strength according to the shades or tints to be obtained."
For preparing the said concentrated vat, I use for example 10 kilogrammes of
indigo reduced in a fine powder, with which I mix 10 litres of hot water at about
60 degrees in order to properly moisten the indigo and then add 20 litres of thick
lime-milk containing from 6 to 7 kilogrammes of dry lime.
Into a zine bucket I put 25 kilogrammes of sodium bisulphite at 30 degrees
Baum, and mix therewith from 2 to 3 kilogrammes of zine powder according to
the state of oxidation of the powder, and agitate moderately for a few seconds. The
liquid soon becomes hot, and loses the odour of sulphurous acid. I then pour the
hydrosulphite obtained in this manner into the mixture of lime and indigo.
The whole preparation rapidly coagulates, in a few minutes the coagulation ceases,
the liquid is golden yellow and is covered with a thick flower. The indigo is
redneed and dissolved.
It is expedient to use an abundant quantity of zinc powdor in the preparation of
the hydrosulphite as above specified, in order that the reaction shall be effected in a
minute at most. The hydrosulphite becomes debased in contact with the air and
cannot be preserved.
I put in the dye vat a sufficient quantity of the reduced indigo from the
concentrated vat for obtaining the desired tint in a single steeping operation.
For each fresh charge of wool indigo is introduced and when the bath oxidizes
hydrosulphite prepared as above described is added.
For obtaining a vat without a deposit and a brighter dye the hydrosulphite may
be purified in the following manner, the hydrosulphite having been prepared as above
stated an equal quantity of somewhat clear lime milk is added. After waiting

page_text: about a minute it is poured into the vat, through a filtering medium consisting of a
somewhat thick packing cloth.
In the case of deep tints when the bath contains a considerable quantity of indigo,
it is expedient to squeeze the wool and expose it to the air on leaving the vat, whilst
the liquid squeezeil ont is caused to return to the vat, being brought as little as
possible in contact with the air. As the means ordinarily employed are quite
inadequate for fulfilling these various conditions I employ apparatus of special
construction in connection with the vat which apparatus is represented in side
elevation in the accompanying drawing.
This apparatus is arranged by the side of the vat X and comprises a frame B
carrying two rollers A. A the upper roller being pressed upon the lower one by
levers provided with counterweights which levers act upon vertical rods D resting
upon the bearings for the said upper roller. In front of the said rollers is arranged
an endless apron O upon which the wool taken from the dye bath is thrown. From
this apron the wool passes between the rollers and is thereby freed from the excess
of dye which flows down upon an inclined plane E and returns to the vats.
At the rear of the rollers is arranged a fan V for airing the wool in its passage
from the rollers. This apparatus can if desired be replaced by a hydroextractor of
any construction adapted for drying and airing the wool as soon as it leaves the vat.
The passage of the wool to the squeezing device presents the advantage of ensuring
the uniformity of the dye upon the wool.
For the purpose of effecting a still greater economy in the case of baths which
contain a great quantity of indigo it is advisable to rinse the dyed wool in a small
quantity of water which takes up the indigo that is not fixed upon the wool. A
second squeezing device must in this case be added to the rinsing bath. When this
bath is sufficiently concentrated it is caused to pass into the vat or is utilized in the
precipitation of the indigo.
The above-mentioned proportions used in the preparation of the several mixtures
depend to a great extent upon the nature of the indigo, bisulphite, zinc, and other
substances, and can be varied.
It is necessary to avoid the employment of hydraulic lime.
This process for dyeing can also be applied to the dyeing of cotton which is
effected with vats of indigo mounted as hereinbefore described and operating either
cold or hot.
vat.
I have moreover devised means for brightening the blue dye of the hydrosulphite
Wool dyed in my hydrosulphite vat has ordinarily a greenish or greyish appear-
ance when it has just been dyed. A long exposure to the air removes this defect.
In most cases it is necessary to remedy this defect in a prompter manner and
brighten the wool by freeing it from certain salts produced in the vat and forming a
kind of veil upon the colour, or by oxidizing the wool in an artificial and expeditious
manner.
For example the wool coming from the rat and deprived of its green colour
(about one hour being needed for deep-coloured dyes) may be put in a hot bath of
hydrochloric acid. After remaining therein for from one to two hours, the bath is
removed the wool remaining in the boiler is raised upon a bar and covered so as to
remain under the action of the heat or preferably steam. If needed vaporization
may be effected in a special chamber. The wool is left in the steam for about two
hours and is then rinsed in the ordinary manner.
The hydrochloric acid can be employed in the proportion of five per cent.
Use
can also be made of sulphuric acid in the same proportion, and also acids or acid
salts which do not attack either the wool or the colour. Furthermore use may be
made of sulphides and chlorides (culinary salt producing a good effect), oxygenated
water either alone and diluted or combined with an acid, barium dioxide and in
general any oxidizing agents in suitable proportion.
This brightening which succeeds the dyeing has also the effect of collecting all
the indigo not fixed upon the wool. This indigo is again found in the rinsing bath

page_text: and gives na economy which is much greater than the expense occasioned by this
supplementary operation.
With certain sulphides for example sodium sulphide, the rinsing bath to which a
little olein is addeil, gives back to the wool all the colour which may be removed
later on by the fulling, the wool leaves the bath perfectly clean, and this rinsing
bath can be transformed into a vat by the simple addition of hydrosulphite. The
indigo can thus be collected upon white wool. With acid rinsing baths the indigo
is easily precipitated and collected at the bottom of the receptacles.
Having now particularly described and ascertained the nature of my inven
tion, and in what manner the same is to be performed, I declare that what I
glaim is
First. My process for dyeing indigo, which consists in rapidly and economically
preparing a concentrated bath of indigo and hydrosulphite by pouring directly into
the indigo suspended in the lime milk the liquor charged with hydrosulphite which
proceeds from the rapid reaction of the zine powder in excess of the bisulphite.
Second. The optional adjunction, to the dye vats of more or less deep colour, of
a squeezing apparatus which removes the liquid in excess and rapidly airs the
material, which enables the dyeing, even in deep colours, in one operation, the
material being if necessary washed and then dried.
Third. The employment of my vat for dyeing wool, cotton and any vegetable
libres, either cold or hot.
Fourth. The rinsing devices hereinbefore described having the effect of brighten-
ing the blue colours obtained by my system of vat containing hydrosulphite.
Dated this 5th day of February 1891.
HASELTINE, LAKE & Co..
45, Southampton Building, Loudon, W.C., Agents for the Applicant.