IMPROVE- MENTS IN THE PRINTING OF INDIGO UPON TEXTILE FABRICS
Year: 1884

page_text: I, GEORGE HILL UNDERWOOD of 5 Sugar Lane Manchester in the County of
Lancaster Drysalter do hereby declare the nature of my invention.for IMPROVE-
MENTS IN THE PRINTING OF INDIGO UPON TEXTILE FABRICS to be as follows:-
This Invention consists principally in the use of sulphides of arsenic in the
manner hereinafter explained for the purpose of de-oxydizing the Indigo after it is
printed upon the textile fabric by which means the most satisfactory results are
obtainable.
.
I first take the textile fabric and I "pad" or print on the surface a sulphide
of arsenic, such for instance as is known as red or yellow arsenic, mixed with
starch or other suitable thickening material.
Or I "pad" or print on the surface an alkaline solution or carbonated alkaline
solution of such sulphide of arsenic.
"
Or I " pad
or print an ammoniacal solution of the sulphides of arsenic on the
textile fabric and then dry the cloth in the usual manner. This I call the
prepared or mordanted cloth."
I prefer to use for thus preparing the cloth to receive the indigo, the sulphide
of arsenic known in commerce as "red arsenic;" I do not, however, restrict myself
to this particular sulphide of arsenic, as other sulphides of arsenic will give fair
results.
Of the alkalies, alkaline earths or alkaline carbonates (or other alkaline salts in
which the above sulphides are soluble) used in solution therewith I prefer to use
caustic soda and its carbonates but good results can be obtained by the use of
other alkalies; or strong liquid ammonia or carbonate of ammonia may be used.
For printing on this "prepared or mordanted cloth " I use commercial Indigo,
by preference of fair quality which I grind or triturate in water, or in alkaline
solutions or other suitable liquid, to the consistency of a fine paste. To this Indigo
paste I add thickening, material such as dry British gum, or starch, and after this
mixture is thoroughly made, I add to it a strong solution of a caustic alkali
(preferably caustic soda on account of its cheapness) the whole is then mixed into
an even paste, and it is then ready for printing onto the "prepared or mordanted
cloth."

page_text: After thus preparing, printing and drying I pass the printed fabric through an
atmosphere of steam, or I steam it in the ordinary way as practised by calico
printers. By this process the Indigo becomes de-oxydized, or reduced to what is
termed "the white state" on the surface of the textile fabric.
In the subsequent processes of ageing souring and washing the Indigo re-absorbs
oxygen from the atmosphere and assumes the well known Indigo blue color.
My improved process therefore is a four fold one.
»
1. "Pad or print on the surface of the fabric with an alkaline or other solution
of sulphide of arsenic as a preparation or mordant.
2. Print the pattern thereon with an alkaline indigo paste thickened with gum
or starch.
3
3. Steam the printed fabric to de-oxydize the indigo, and convert it into "white
indigo.
4. Age, sour, and wash till it becomes re-oxydized and assumes the indigo blue
color.
Dated this first day of January 188A
GEORGE DAVIES,
Agent for the Applicant.

page_text: I GEORGE HILL UNDERWOOD of 5, Sugar Lane Manchester in the County of
Lancaster Drysalter do hereby declare the nature of my invention for "IMPROVE-
MENTS IN THE PRINTING OF INDIGO UPON TEXTILE FABRICS
" and in what manner
the same is to be performed to be particularly described and ascertained in and
by the following statement:-
This invention consists principally in the use of sulphides of arsenic in the
manner hereinafter explained for the purpose of de-oxydizing the Indigo after it is
printed upon the textile fabric by which means the most satisfactory results are
obtainable.
"
I first take the textile fabric and I "pad or print on the surface a sulphide of
arsenic, such for instance as is known as red or yellow arsenic, mixed with starch
or other suitable thickening material.
Or I pad or print on the surface an alkaline solution or carbonated alkaline
solution of such sulphide of arsenic.
Or I "pad' or print an ammoniacal solution of the sulphides of arsenic on the
textile fabric and then dry the cloth in the usual manner. This I call the "prepared
or mordanted cloth."
I prefer to use for thus preparing the cloth to receive the indigo the sulphide
of arsenic known in commere as red arsenic " I do not however restrict myself
to this particular sulphide of arsenic, as other sulphides of arsenic will give fair,
results.
Of the alkalies, alkaline earths or alkaline carbonates (or other alkaline salts in
which the above sulphides are soluble) used in solution therewith I prefer to use
caustic soda and its carbonates but good results can be obtained by the use of other
alkalies or strong liquid ammonia or carbonate of ammonia may be used.
For printing on this prepared or mordanted cloth I use commercial Indigo, by
preference of fair quality which I grind or triturate in water, or in alkaline solutions
or other suitable liquid to the consistency of a fine paste. To this Indigo paste
I add thickening material such as dry British gum, or starch, and after this
mixture is thoroughly made, I add to it a strong solution of a caustic alkali
(preferably caustic soda on account of its cheapness) the whole is then mixed into
an even paste, and it is then ready for printing onto the "prepared or mordanted
cloth."
After thus preparing, printing and drying I pass the printed fabric through an
atmosphere of steam, or I steam it in the ordinary way as practised by calico
printers. By this process the Indigo becomes de-oxydized, or reduced to what is
termed the "white state" on the surface of the textile fabric.
In the subsequent processes of ageing scouring and washing the Indigo re-absorbs
oxygen from the atmosphere and assumes the well known Indigo blue color.
My improved process therefore is a four fold one.
1. "Pad" or print on the surface of the fabric with an alkaline or other solution
of sulphide of arsenic as a preparation or mordant.
2. Print the pattern thereon with an alkaline indigo paste with or without being
thickened with gum or starch.
3. Steam the printed fabric to de-oxydize the indigo, and convert it into "white
indigo."
4. Age, sour, and wash till it becomes re-oxydized and assumes the indigo blue
color,

page_text: The following proportions answer and give good practical results, but I do not
bind myself to the particular proportions mentioned below as variations of these
proportions give results of a fairly satisfactory character.
For the color I take one pound of the Indigo paste containing about thirty three
per cent of dry indigo, of British gum three ounces, and I mix these well together
and then slowly add one pint of caustic soda, at about 90° Twaddles hydrometer,
the color is then ready to print upon the prepared cloth.
I make the alkaline solutions of the sulphides of arsenic as follows.
A. I take two pounds of carbonate of soda crystals and one gallon of water to
which I add eight ounces of the sulphide of arsenic known in commerce as red
arsenic, this mixture I boil for about one hour making up the loss occasioned by
evaportion, so that I have one gallon of fluid, the clear liquor is then drawn off and
is ready for use in preparing the cloth to receive the Indigo color.
B-Or I take one gallon of caustic soda at about 10° Twaddles hydrometer and
add to it eight ounces of the sulphide of arsenic known in commerce as red arsenic
which I boil for about one hour making up the loss occasioned by evaporation
upon cooling, I then decant the clear liquor and it is then ready for use in
preparing the cloth for printing the indigo color upon it.
C. Or I take a strong liquid ammonia say one gallon, to which I add ten ounces
of the above named red arsenic, previously mixing it into a paste with water, I let
this mixture stand for about 24 hours giving it frequent agitation, then decant
the clear liquor, which is then ready for preparing the cloth to receive the indigo
color.
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 improved process of printing indigo upon textile fabrics by first
padding the cloth with an alkaline or other solution of sulphide of arsenic as a
preparation and then printing thereon with an alkaline indigo paste.
Dated the 30th day of September 1984