IMPROVEMENTS IN INDIGO-PRINTING
Year: 1881

page_text: LETTERS PATENT to Frank Wirth, of the Firm of Wirth and Company,
Patent Solicitors, at Frankfort on the Main, in the Empire of Germany,
for an Invention of IMPROVEMENTS IN INDIGO-PRINTING." A communi-
cation from Julius Ribbert, of Hohenlimburg, in the Empire of Germany.
"
PROVISIONAL SPECIFICATION left by the said Frank Wirth at the Office
of the Commissioners of Patents on the 8th October 1881.
FRANK WIRTH, of the Firm of Wirth and Company, Patent Solicitors, at
Frankfort on the Main, in the Empire of Germany. "IMPROVEMENTS IN INDIGO-
PRINTING." [A communication from Julius Ribbert, of Hobenlimburg, in tho
Empire of Germany.]
According to this Invention the ordinary indigo of commerce is soaked for
about 24 hours in caustic soda lyo of 20° Beaumé, and then ground in an indigo
mill. Dextrine as free as possible from sugar is worked up into a paste with water,
and then stirred together with the indigo, after which the mixture is placed in a
receptacle with water jacket for the circulation of cold water, and dry caustic
soda is added very gradually under continual stirring, and in such proportions
that the temperature does not rise above about 88° Fahr. The mixture is then
allowed to remain for about 6 hours under exclusion of the air, after which it is
ready for printing on the fabric.
The fabric to be printed upon is for this purpose previously impregnated with
grape sugar, and after being printed upon with the indigo compound, it is
subjected for about five minutes to moist steam.
By this means the indigo becomes reduced by the reaction of the caustic soda
and sugar. The fabric is then passed through water for about 30 minutes, whereby
the indigo becomes oxidised, after which the fabric is dried and is then ready
for use.
The proportions which it is preferred to employ in the above process are about
25 parts by weight of indigo, 44 parts of caustic soda, 5 parts of dextrine, and
GS parts of water, and a quantity of grape sugar equal to about 20 per cent. of the
total of the above compound is employed for impregnating the fabric; but I do not
limit myself to these proportions, as they may vary between wide limits according
to the shade of colour to be obtained.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Frank Wirth in the Great Seal Patent Office on the 21st March
1882.
FRANK WIRTH, of the Firm of Wirth and Company, Patent Solicitors, at
Frankfort on the Main, in the Empire of Germany. "IMPROVEMENTS IN INDIGO-
PRINTING." A communication from Julius Ribbert, of Hohenlimburg, in the
Empire of Germany.
According to this Invention the ordinary indigo of commerce is soaked for about
24 hours in caustic soda lye of 20° Beaumé, and then ground in an indigo mill.
Dextrine as free as possible from sugar is worked up into a paste with water, and
then stirred together with the indigo, after which the mixture is placed in a
receptacle with water jacket for the circulation of cold water, and dry caustic soda
is added very gradually under continual stirring, and in such proportions that
the temperature does not rise above 88° Fahr. The mixture is then allowed to
remain for about 6 hours under exclusion of the air, after which it is ready for
printing on the fabric.
The fabric to be printed upon is for this purpose previously impregnated with
grape sugar, and after being printed upon with the indigo compound, it is subjected
for about five minutes to moist steam. By this means the indigo becomes reduced
by the reaction of the caustic soda and sugar. The fabric is then passed through
water for about 30 minutes, whereby the indigo becomes oxidised, after which the
fabric is dried and is then ready for use.
The proportions which it is preferred to employ in the above process are about
25 parts by weight of indigo, 44 parts of caustic soda, 5 parts of dextrine and
68 parts of water, and a quantity of grape sugar equal to about 26 per cont. of the
total of the above compound is employed for impreguating the fabric; but I do not
limit myself to these proportions, as they may vary between wide limits according
to the shade of colour to be obtained.
Having thus described the nature of the said Invention and in what manner the
same is to be performed, as communicated to me by my correspondent, I claim,―
The herein described process for printing with indigo, wherein the indigo, after
treatment with caustic soda, is printed on the fabric and subjected to the action of
steam in the presence of sugar, the indigo being afterwards reoxidised by passing
through water.
In witness whereof, I, the said Frank Wirth, have hereunto set my hand
and seal, this Fourteenth day of March, in the year of our Lord One