IMPROVEMENTS IN THE TREATMENT OF INDIGO FOR DYEING AND PRINTING
Year: 1875

page_text: LETTERS PATENT to George Hill Underwood, of Manchester, in the
County of Lancaster, for the Invention of "IMPROVEMENTS IN THE
TREATMENT OF INDIGO FOR DYEING AND PRINTING."
Sealed the 10th March 1876, and dated the 6th December 1875.
PROVISIONAL SPECIFICATION left by the said George Hill Under-
wood at the Office of the Commissioners of Patents, with his
Petition, on the 6th December 1875.
I, GEORGE HILL UNDERWOOD, of Manchester, in the County of Lan-
5 caster, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN THE TREATMENT OF INDIGO FOR DYEING AND PRINTING," to be as
follows:-
This Invention consists principally in the use of phosphorous for the
purpose of deoxidising indigo for dycing or printing, by which means
) most satisfactory results are obtainable.
I use commercial indigo, by preference of fair quality, which I grind
or triturate in water, alkaline solution, or other suitable liquid to the con-

page_text: .
sistency of a fine paste. With the paste so prepared I mix a certain
quantity of any of the caustic alkalies or alkaline earths, such as
caustic soda, potash, or lime, or a mixture of any of these caustic
alkalies or alkaline earths, in such proportions as shall be deemed
most expedient for practical application in dyeing or printing in the
discretion of the operator. To this mixture of the alkalies and the
indigo paste I add gradually cither amorphous (known also as red or
granulate) phosphorous, or phosphorous dissolved in any of its solvents,
or phosphorous triturated in fatty (or other suitable) matters, and thus
reduced to a fine state of division. After the addition of phosphorous in 1
any of the above forms to the indigo or alkalies, I thoroughly mix the
whole together, and the preparation is then ready for printing, the
indigo remaining in the blue or oxidised state.
After printing and dyeing I pass the printed fabric through an atmo-
sphere of steam, or steam it in the ordinary way as practised by calico 1
printers, and by this process the indigo becomes deoxidised or reduced to
the white state on the surface of the textile fabric.
In the subsequent processes of ageing, souring, and washing, the
indigo gradually absorbs oxygen, and assumes the well-known indigo
blue color.
In some instances instead of proceeding as above I deoxidise or reduce
the indigo to the white state by heating the above mixture of indigo,
alkalies, and phosphorous, and in this state it can be printed on to the
fabric, which can then be aged, soured, and washed off with or without
the steaming process, at the option of the operator.
The following proportions answer and give fair 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.
2
2
Of the alkalies or alkaline salts I prefer commercial liquid caustic 3
soda standing about 70° Twaddle's hydrometer, but this is on the score
of cheapness only, as caustic potash would answer as well.
Respecting the use of lime (used in a pulpy state by slacking com-
mercial lime with water, and throwing the same on a filter frame and
leaving it until it assumes a pulpy or thick consistency), I can dispense 3
with the use of it if required.

page_text: For obtaining lighter shades from the following color I simply reduce
the color by reducing it with one of the caustic alkalies thickened with
British gum or other thickening substances well known to calico
printers. By this means various shades of blue from dark to light is
obtained.
The following is a composition of the color which gives fair results,
but as said before I don't confine myself strictly to this composition :—
1 lb. pulp indigo containing about 8 oz. of fair commercial indigo; % oz.
red or amorphous phosphorous; 9 fluid ounces of caustic soda standing
about 70° Twaddle's hydrometer; ½ oz. pulp lime.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said George Hill Underwood in the Great Seal Patent
Office on the 3rd June 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
HILL UNDERWOOD, of Manchester, in the County of Lancaster, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Sixth day of December, in the year
of our Lord One thousand eight hundred and seventy-five, in the
thirty-ninth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said George Hill Underwood,
Her special license that I, the said George Hill Underwood, my exe-
cutors, administrators, and assigns, or such others as I, the said George
Hill Underwood, my executors, administrators, and assigns, should at
any time agree with and no others, from time to time and at all
times thereafter during the term therein expressed, should and law-
fully might make, use, exercise, and vend, within the United Kingdom
of Great Britain and Ireland, the Channel Islands, and Isle of Man,
an Invention for "IMPROVEMENTS IN THE TREATMENT OF INDIGO FOR DYEING
AND PRINTING," upon the condition (amongst others) that I, the said
George Hill Underwood, my executors or administrators, by an instru-
ment in writing under my, or their, or one of their hands and seals,
should particularly describe and ascertain the nature of the said
Invention, and in what manner the same was to be performed, and

page_text: cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said George Hill Underwood, do hicreby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement (that is to say) :-
This Invention consists principally in the use of phosphorus for the
purpose of deoxidising indigo for dyeing and printing, by which means
most satisfactory results are obtainable.
I use commercial indigo, by preference of fair quality, which I grind
or triturate in water, alkaline solution, or other suitable liquid to the con-
sistency of a fine paste. With the paste so prepared I mix a certain
quantity of any of the caustic alkalies or alkaline earths, such as
caustic soda, potash, or lime, or a mixture of any of these caustic
alkalies or alkaline earths, in such proportions as shall be deemed most
expedient for practical application in dyeing or printing at the discretion
of the operator. To this mixture of the alkalies and the indigo paste I
add gradually either amorphous (known also as red or granulate) phos-
phorus, or phosphorus dissolved in any of its solvents, or phosphorus
triturated in fatty or other suitable matters, and thus reduced to a fine
state of division. After the addition of the phosphorus in any of the
above forms to the indigo and alkalies, I thoroughly mix the whole
together, and the preparation is then ready for printing, the indigo
remaining in the blue or oxidised state.
After printing and drying I pass the printed fabric, warp, or yarn
through an atmosphere of steam, or steam it in the ordinary way as
practised by calico printers, and by this process the indigo becomes
deoxized or reduced to the white state on the surface of the textile
fabric.
The cloth or yarn may be steamed by any of the ordinary methods
well known to calico printers, but for cloth I prefer the following mode
of steaming-I take a perforated metallic cylinder open at both ends
about twelve inches in diameter, having hooks attached so that it can be
suspended in the steam box; over the cylinder I wrap about three folds
of blanket, and then wind the printed cloth along with a grey cloth
upon the cylinder (or the printed cloth alone without the grey cloth),

page_text: and then cover the whole with a banket and suspend it in the steam box
to be subjected to the action of steam. The duration of steaming
depends in some measure upon the heaviness of the pattern or amount
of colour printed upon the fabric, but one hour will under nearly all
circumstances be found sufficient to effect a perfect reduction or deoxi-
dization of the indigo. After steaming, the textile fabric or material is
washed in a plentiful supply of water, or in water acidulated with an
and then cover the whole with a banket and suspend it in the steam box
to be subjected to the action of steam. The duration of steaming
depends in some measure upon the heaviness of the pattern or amount
of colour printed upon the fabric, but one hour will under nearly all
circumstances be found sufficient to effect a perfect reduction or deoxi-
dization of the indigo. After steaming, the textile fabric or material is
washed in a plentiful supply of water, or in water acidulated with an
acid.
In the subscquent processes of ageing, souring, and washing, the
indigo gradually absorbs oxygen, and assumes the well-known indigo
blue color.
In some instances instead of proceeding as above I deoxidize or reduce
the indigo to the white state by heating the above mixture of indigo,
alkalies, and phosphorus, and in this state it can be printed on the fabric
or yarn, which can then be aged, soured, and washed off with or without
the steaming process at the option of the operator.
Of the alkalies or alkaline salts to be used in this process I prefer
liquid caustic soda standing about eighty-five degrees Twaddle's hydro-
meter, but this is on the score of cheapness only, as caustic potash would
answer as well.
Respecting the use of lime (used in a pulpy state by slaking com-
mercial lime with water, and throwing the same on a filter frame and
leaving it until it assumes a pulpy or thick consistency), I can dispense
with the use of it if required.
For obtaining light shades from the following I simply reduce the
color by the addition of one of the caustic alkalies thickened with
British gum or other thickening substances well known to calico
printers. By this means various shades of blue from dark to light are
obtained.
The following proportions answer and give fair practical results, but
I do not bind myself to the particular proportions mentioned, as varia-
tions of these proportions give results of a fairly satisfactory character:―
One pound of pulp indigo containing about eight ounces of fair com-
mercial indigo; three ounces of amorphous (known also as red or
granulate) phosphorus; one pint of liquid caustic soda standing about
eighty-five degrees Twaddle's hydrome! ; and one ounce of pulp lime.

page_text: By mixing some of the metallic oxides with the above described color
other effects or colors than blue can be produced, such as the following:—
A green can be obtained by mixing with the above described color an
oxide of lead, and after printing and going through the steaming process,
then being soured in sulphuric acid, washed and raised in a solution of
chromate of potash; or alumina may be mixed with the color, and after
printing, steaming, &c., the fabric or yarn may be dyed with madder or
other dyeing materials, and so produce the desired effect.
Having now described the nature and object of my said Invention,
together with the manner in which the same is to be or may be per-
formed or carried into practical effect, I wish it to be understood that I
claim as my Invention,―
First. The treatment of indigo with phosphorus, either in the amor-
phous state (known as red or granulate phosphorus) or in the ordinary
state dissolved in suitable solvents, or reduced to a fine state of division
by trituration with fatty or other suitable matters, or in any other way,
as a reducing agent to facilitate the deoxidation and fixation of the
indigo upon textile fabrics or yarns, as applied in the manner herein
described for producing various shades of blue color.
Secondly. I claim the treatment of indigo with phosphorus in com- 1
bination with metallic oxides, such as those of tin, lead, or alumina, as
described, for the production of other colors than blue.
4
In witness whereof, I, the said George Hill Underwood, have
hereunto set my hand and seal, this Thirtieth day of May, in
the year of our Lord One thousand eight hundred and seventy- :
six.