Improved Method of using Indigo White for Printing.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improved Method of using Indigo White for Printing.
I, JACOB GROSSMANN, of Harpurhey Chemical Works, Manchester, Mann-
facturing Chemist, do hereby declare the nature of this invention to be as
follows:-
Attempts have been made from time to time to use Indigo White for Printing;
but the results have not been satisfactory; the colour became oxidized in the pro-
cess of printing and the results obtained were irregular and of a bad shade of blue.
I have overcome these defects by adding to the mixture of White Indigo and
caustic Soda solution 'a mixture of Zinc Powder or Aluminium powder or any
similar metallic powder and Glucose or a similar organic compound; and bring-
ing these with a suitable thickening to the proper consistency. The resulting
colour is printed in the usual way either cold or slightly warmed. The printed
cloth is then passed over hot plates, dried quickly and then steamed for a few
minutes; it is afterwards exposed to a moist atmosphere until the oxidation of the
reduced Indigo is completed, & may then be soured or not according to require-
ments.
Dated this twenty-seventh day of May 1897.
COMPLETE SPECIFICATION.
Improved Method of using Indigo White for Printing.
I, JACOB GROSSMANN, of Harpurhey Chemical Works, Manchester, in the
county of Lancaster, Manufacturing Chemist do hereby declare the nature of this
invention and in what manner the same is to be performed, to be particularly
lescribed and ascertained in and by the following statement:-
-
For a number of years attempts have been made to print Indigo white in one
operation in such a manner that it should only require ageing or steaming and
ageing to fix & develop the blue colour after printing. All these attempts proved
unsuccessful as the printing colour oxidized too quickly even though in some
cases complicated apparatus was used either to prevent the access of air to the
colour or to keep the colour in an atmosphere of an inert gas during the process
of printing. In 1871 Paul Schutzenberger & Felix de Lalande obtained an
English Patent No. 3377 entitled "Indigo Printing & Dyeing" in which they
proposed to reduce the Alkalinity of the colour by using Bicarbonate of soda or
any other feebly acid salt in conjunction with indigo white at the same time add-
ing hydrosulphite in order to retard the oxydation. The drawbacks of this method
are that the reducing agent used is in itself an unstable compound & that for
T

page_text: printing purposes a feebly acid substance such as Bicarbonate of Soda is unsuit-
able for producing satisfactory results. In fact I have found that in order to pro-
duce a good shade of blue with indigo white economically, it is necessary that the
colour should be strongly caustic and there should be a quantity of caustic Alkali
present largely in excess of the quantity required by theory. Such a strongly
alkaline colour however being very easily oxydizable, it is necessary to add such
reducing agents as are in themselves of a stable character. Such I have found to
be Glucose, Zinc dust, Aluminium dust, or similar substances preferably a mixture
of Glucose & Zinc dust.
Having thus described the principle of my method I now proceed to give details
of its application. The Indigo white pulp may be obtained from natural or
artificial Indigo by any method known to Chemists & may contain conveniently
about ten per cent. heneoindigotine. A thickening is prepared which may be
made for an example, by mixing thirty two parts of calcined gum with sixty seven
parts of Caustic soda solution of 70° Twaddle, and one part of Turpentine;
seventy six parts of this thickening are mixed well with twenty parts of the
Indigo white paste & with four to ten parts of Glucose, then about half a part or
more of finely sieved Zine dust are added & mixed & stirred well till quite homo-
geneous. The colour may be strained before or after adding the Zinc dust. If
it should froth too much it may be left to stand to subside or a little more
Turpentine or a little Ether may be added. This is the Standard colour which
may of course be made stronger by using stronger Indigo white paste & altering
the other ingredients in proportion. This colour may be reduced for lighter shades
by adding a suitable caustic thickening, but care should be taken that the thicken-
ing should be free from occluded air or Oxygen, & it is therefore best to add to
the thickening a little more Zinc, Caustic & Glucose or any other suitable deoxi-
dizer. I do not bind myself to the use of gum as a thickener nor to the exact pro-
portions of the other parts described above, as they may be varied according to
circumstances. Thus c.g. where there is much air in the steambox it is well to
increase the quantity of Zinc & of Glucose & even to add other substances which
will absorb Oxygen such as Sulphite of Soda or similar compounds, specially
where dark shades are required.
The colour is printed in the ordinary way & the printed pieces are carefully.&
quickly dried just sufficiently to harden the gum or other thickening matter used.
The pieces are then passed through a suitable steambox & steamed in fairly moist
steam & with exclusion of air for a period of from one to three minutes or longer
according to the construction of the box & the condition of the steam; when leav-
ing the steamer the colour should be brownish olive. The goods are then passed
into a room containing a very moist atmosphere & are hung there till quite blue;
or they may be wetted carefully by a Water spray & left to hang till blue. After
that they may be treated in any way required as known to Calico printers.
Having now particularly described the nature of my invention & in what
manner the same is to be performed I declare what I claim is
The use for printing of a mixture of Indigo white with, or solution of the same
in, an excess of a caustic Alkali in conjunction with glucose and zinc dust or
similar stable reducing agents as described above.
Dated this twenty-ninth day of October 1897.