Process for Obtaining Designs or Patterns in Red Colour on Textile Fabrics Dyed with Indigo
Year: 1890

page_text: Date of Application, 14th May, 1890
Complete Specification Left, 20th Jan., 1891-Accepted, 21st Feb., 1891
PROVISIONAL SPECIFICATION.
Process for Obtaining Designs or Patterns in Red Colour on Textile
Fabrics Dyed with Indigo.
I, Dr. WILHELM ELBERS, Analytical Chemist, of Hagen, in Westphalia,
Germany, do hereby declare the nature of this invention to be as follows:-
My invention has for its object, to produce patterns or designs in red azo-colour
on fabrics which have been dyed blue in the indigo-bath.
The red azo-dye is produced directly on the fibre during the operation of printing,
in the following manner :-
The fabric, after having been dyed in the indigo-vat, then washed and dried on
the hot flue, is patted with a specially prepared solution of beta-naphthol ; on the
following day, the desired pattern or design is printed on the fabric with a specially
prepared red azo-dye, after which the fabric is allowed to hang over night,
subsequently passed through a specially prepared corroding bath for about half a
minute at a temperature of 44° C., and finally well washed and dried.
The solution of beta-naphthol is composed of :-
Beta-naphthol
Water
Caustic soda of 36° Beaumé
Turkey-red oil
Water
40 grammes solution.
200
40
150
دو
وو
(hot).
1,200
(cold).
"
The red azo-dye is composed as follows:-
Chromate mixture
Diazotized amido-azo-benzene-
Nitrate of soda, pulverised
Acetate of lime at 15° Beaume
Acetate of alumina, at 11° Beaumé
Tin-salt (Sn. C₁₂ + 2 H2O) -
200 grammes.
200
"
10
29
10
""
-
5
22
"
The chromate paste mentioned above is obtained by boiling a mixture of
1,600 grammes of acid chromate of potash with 1,140 grammes of crystalline soda,
and 1,250 grammes of water, until all carbonic acid is driven out, pouring the hot
liquid upon 4,220 grammes of tragacanth water (60 grammes for each litre),
allowing to cool and adding 220 grammes of ammonia at 20° Beaumé.
The quantity of chromate of potash in the red azo-dye is sufficient to destroy
during the subsequent corroding or pickling operation a moderately deep indigo-
dye at the places which have been touched by an engraved roller with medium
depth of engraving. For darker shades of indigo the chromate mixture should be
more concentrated, or the printing surfaces should be engraved to a greater depth.
The diazotised amido-azo-benzene is prepared as follows:-
Amido-azo-benzene N 220 g. (25 per cent. amido-azobene

page_text: I and II are mixed together and filtered; 40 grammes of chalk are mixed with
170 grammes of water, to form a paste, which is then added to the above product
and the mixture is again filtered.
The corroding bath is composed of
The red azo-dye is formed after the printing, but appears brown, because it lies
on a blue ground. During the subsequent process of corroding, the chromate of
potash in conjunction with the sulphuric and the oxalic acid, destroys the indigo, at
the places which have been printed on, so that after the corroding, they appear red
on a blue ground.
The addition of nitrate of soda and tin-salt. serves to increase the intensity and
brilliancy of the red colour, while acetate of lime and acetate of alumina protect the
same against the action of soap.
L
141 1
1000
FAIRFAX & WETTER,
433, Strand, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
Process for Obtaining_Designs or Patterns in Red Colour on Textile
Fabrics Dyed with Indigo.
I, Dr. WILHELM ELBERS, Analytical Chemist, of Hagen, in Westphalia,
Germany, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement :-
My invention has for its object, to produce patterns or designs in red azo-colour
on fabrics which have been dyed blue in the indigo-bath.
The red azo-dye is produced directly on the fibre during the operation of printing,
in the following manner
The fabric, after having been dyed in the indigo-vat, then washed and dried on
the hot flue, is padded with a specially prepared solution of beta-naphthol; on the
following day, the desired pattern or design is printed on the fabric with a
specially prepared red azo-dye, after which the fabric is hung up over night,
subsequently passed through a specially prepared pickling bath for about half a
minute at a temperature of 44 C., and finally well washed and dried.
The solution of beta-naphthol mentioned above, is composed of―
Beta-naphthol
Water
Caustic soda of 36° Beaumé
Turkey-red oil
Water
40 grammes
200
$} solution.
دو
40
">
(hot).
150
"
- 1,200
}(cold).
"
The red-azo-dye mentioned above is composed as follows:-
Chromate paste
Diazotized amido-azo-benzene
Nitrate of soda, pulverised
Acetate of lime at 15° Beaumé
Acetate of alumina, at 11° Beaumé
Tin-salt (Sn. Cl2 + 2 H, O)
-
200 grammes.
200
"
10
"
10
"
5
23
"
The chromate paste mentioned above is obtained by boiling a mixture of
1,600 grammes of acid chromate of potash with 1,140 grammes of crystalline soda,
and 1,250 grammes of water, until all carbonic acid is driven out pouring the hot

page_text: liquid upon 4,220 grammes of tragacanth water (60 grammes for each litre),
allowing to cool and adding 220 grammes of ammonia at 20° Beaumé.
The quantity of chromate of potash in the red azo-dye is sufficient, to destroy
during the subsequent pickling or corroding operation a moderately deep indigo-dye
at the places which have been touched by an engraved roller with medium depth of
engraving. For darker shades of indigo, the chromate mixture should be more
concentrated, or the printing surface should be engraved to a greater depth.
The diazotised amido-azo-benzene is prepared from two solutions composed as
follows:-
During the subsequent process of pickling, the chromate of potash in conjunction
with the sulphuric and the oxalic acid, destroys the indigo, at the places which have
been printed on, so that after the pickling, they appear red on a blue ground.
The addition of nitrate of soda and tin-salt serves to increase the intensity and
brilliancy of the red colour, while acetate of lime and acetate of alumina protect the
same against the action of soap.
I am aware, that before the date of my invention red azo-dye has been produced
on textile fibres by padding the fabric with a solution of beta-naphthol and sub-
sequently printing on it with a solution of diazotised amido-azo-benzene, and do not,
therefore, claim this process generally.
The principal feature of novelty of my process or the leading principle of my
invention consists in adding to the printing ink or dye, bodies which during the
subsequent process of printing destroy the indigo at the places which have been
printed on, without acting injuriously on the azo-dye.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is
1. The process for obtaining azo-red on indigo-blue, which consists in padding
the fabric dyed indigo-blue, with a solution of beta-naphthol prepared as described,
subsequently printing with azo-dye prepared as described, and passing the fabric
through a special pickling or corroding bath, substantially as described.
2. The improvement in the art of producing designs in red azo-colour on textile
fabrics dyed with indigo, which consists in adding to the printing ink or dye, a

page_text: 1
substance which during the subsequent process of pickling destroys the indigo at the
places printed on, without injuring the azo-dye, substantially as described.
Dated this 19th day of January 1891.
W. ELBERS.
By Fairfax & Wetter,
433, Strand, London, Agents.