Improvements in the Production of Indigo on the Fibre, and in Printing with Indigo itself.
Year: 1899

page_text: PROVISIONAL SPECIFICATION.
Improvements in the Production of Indigo on the Fibre,
and in Printing with Indigo itself.
!
I, GEORGE WILLIAM JOHNSON, of 47, Lincoln's Inn Fields, in the County of
London, Patent Agent, do hereby declare the nature of this invention (which
has been communicated to me from abroad by Kalle & Co., of Biebrich-on-Rhine,
in the German Empire) to be as follows:-
My foreign correspondents in following out a process which they have devised
for producing indigo on the fibre by adding a large excess of alkali to a mixture
of indigo salt with a suitable thickening agent, obtaining an impression on the
material with this printing colour, then steaming the printed fabric under com-
plete exclusion of air, and finally developing the indigo upon it by washing,
have found that still better and more uniform results can be obtained by taking
care that the fabric does not become damp during the steaming process, con-
densation of steam on the material being most carefully avoided. The impres-
sions obtained by this means are considerably clearer and more vigorous than
is otherwise the case.
The damping of the fabric during the steaming process can be avoided by using
only dry steam and by heating the fabric before it comes in contact with the
steam, so that the steam cannot condense upon it. This is accomplished by
performing the operation of steaming in an apparatus the interior of which can
be heated to 1000 Centigrade either by using a double jacket or by means of an
internal heater. A quantity of steam is then led into the steaming apparatus
which is heated beforehand, and is provided with a valve for the admission of
steam and an efficient vent for air and steam, and, when the air has been driven.
out by the steam, the printed fabric is drawn into the steaming apparatus through
a slot, and conducted to the interior of the steam-chest over a series of cylinders.
In order to heat the fabric beforehand it is passed over a heated cylinder-or
heated cylinders immediately before entering the steaming apparatus. In an
apparatus so constructed the printed material can remain for a very long period
without becoming in the least degree moist. The steaming for the purpose of
producing the indigo lasts say from five minutes to half an hour, according to
the depth of tint required, and the quantity of steam employed. But even a pro-
tracted retention of the fabric in the steaming apparatus (such as is necessary
in order to combine indigo with other colours, such as alizarine and tannin
colours) is not injurious. Uniform and good results are invariably obtained
by this method.
My foreign correspondents have also found that if these conditions for steam-
ing the material be observed, a printing dye prepared from indigo itself (no matter
whether produced from a natural source or synthetically), caustic soda, and a
thickening agent, may be employed, instead of the dye from indigo-salt, caustic,
soda, and a thickening agent. This also yields good results, and strong, clear.
impressions, but the method is not suitable for producing light shades. In

page_text: preparing the printing dye from indigo itself, it is necessary to reduce the latter
to a highly divided state. The indigo, ground to a fine condition with water,
is then stirred into the thickening, preferably British gum, and treated with a
large quantity of concentrated caustic soda. The fabric is then impressed with
the printing dye so obtained, dried, and steamed, the exclusion of air, and the
avoidance of damping the fabric being essential to the production of good results.
For this purpose an apparatus is best used constructed in the manner hereinbefore
described.
EXAMPLE.
30 kilograms of indigo are ground in a mill, and made into a paste with 50 litres
of water, and triturated during 2 days in a paste mill. The weight of the mass
is then made up to 100 kilograms with water, treated with 50 kilograms of caustic
soda of 45° Beaumé and well agitated.
500 grams of this indigo paste are then slowly stirred into 2500 grams of British
gum-thickening in the proportion 1:1, treated with 1600 grams of water, and
while cooled, with 5400 grams of caustic soda of 45° Beaumé.
The fabric is then impressed with this printing dye, dried and steamed, air
being excluded, and dampening of the material avoided and afterwards it is
washed, acidified, and again washed.
Date : 01
1000
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents.
Improvements in the Production of Indigo on the Fibre,
and in Printing with Indigo itself.
I, GEORGE WILLIAM JOHNSON, of 47, Lincoln's Inn Fields, in, the County of
London, Patent Agent, do hereby declare the nature of this invention (which
has been communicated to me from abroad by Kalle & Co., of Biebrich on Rhine,
in the German Empire) and in what manner the same is to be performed, to
be particularly described and ascertained in and by the following statement:-
My foreign correspondents in following out a process which they have devised
for producing indigo on the fibre by adding a large excess of alkali to a mixture
of indigo salt (bi-sulphite compound of ortho-nitrophenyllactoketone) with a suit-
able thickening agent, obtaining an impression on the material with this printing
colour, then steaming the printed fabric under complete exclusion of air, and
finally developing the indigo upon it by washing, as described in the Specification
of the application for Letters Patent No. 7779 of the 13th April 1899, have
found that still better and more uniform results can be obtained by taking care
that the fabric does not become damp during the steaming process, condensation
of steam on the material being most carefully avoided. The impressions obtained
by this means are considerably clearer and more vigorous than is otherwise the
case.
The damping of the fabric during the steaming process can be avoided by using
only dry steam and by heating the fabric before it comes in contact with the
steam, so that the steam cannot condense upon it. This is accomplished by
performing the operation of steaming in an apparatus the interior of which can
be heated to 1000 Centigrade either by using a double jacket or by means of an
internal- heater. A quantity of steam is then led into the steaming apparatus

page_text: which is heated beforehand, and is provided with a valve for the admission of
steam and an efficient vent for air and steam and, when the air has been driven
out by the steam, the printed fabric is drawn into the steaming apparatus through
a slot, and conducted to the interior of the steam-chest over a series of cylinders.
In order to heat the fabric beforehand it is passed over a heated cylinder, or
heated cylinders, immediately before entering the steaming apparatus. In an
apparatus so constructed the printed material can remain for a very long period
without becoming in the least degree moist. The steaming for the purpose of
producing the indigo lasts say from five minutes to half an hour, according to
the depth of tint required, and the quantity of steam employed, but even a pro-
tracted retention of the fabric in the steaming apparatus (such as is necessary
in order to combine indigo with other colours, such as alizarine and tannin
colours) is not injurious. Uniform and good results are invariably obtained
by this method.
My foreign correspondents have also found that if these conditions for steam-
ing the material be observed, a printing dye prepared from indigo itself (no matter
whether produced from a natural source or synthetically), caustic soda, and a
thickening agent, may be employed, instead of the dye from indigo-salt, caustic
soda, and a thickening agent. This also yields good results, and strong, clear
impressions, but the method is not suitable for producing light shades. In
preparing the printing dye from indigo itself, it is necessary to reduce the latter
to a highly divided state. The indigo, ground to a fine condition with water,
is then stirred into the thickening, preferably British gum, and treated with a
large quantity of concentrated caustic soda. The fabric is then impressed with
the printing dye so obtained, dried, and steamed, the exclusion of air, and the
avoidance of damping of the fabric as aforesaid being essential to the production
of good results. For this purpose an apparatus is best used constructed in the
manner herein before described.
EXAMPLE.
30 kilograms of indigo are ground in a mill, and made into a paste with 50 litres
of water, and triturated during 2 days in a paste mill. The weight of the mass.
is then made up to 100 kilograms with water, treated with 50 kilograms of caustic
soda of 45° Beaumé and well agitated.
500 grams of this indigo paste are then slowly stirred into 2500 grams of
British gum-thickening composed of equal proportions of British gum and water
treated with 1600 grams of water, and while cooled, with 5400 grams of caustic
soda of 45° Beaumé.
The fabric is then impressed with this printing dye, dried, and steamed, air
being excluded, and dampening of the material avoided as herein before described,
and afterwards it is washed, acidified, and again washed.
Having now particularly described and ascertained the nature of this inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is
The improvement in the production of indigo on the fibre or indigo-dyed fibre
by means of indigo-salt (bisulphite compound of ortho-nitrophenyllactoketone)
or natural, or artificial, indigo, consisting in the provision of means for prevent-
ing damping of the printed goods during the steaming process by the applica-
tion of heat, substantially as hereinbefore explained.
Dated this 30th day of January 1900.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents.