IMPROVEMENTS IN DYEING COTTON YARNS AND FABRICS
Year: 1887

page_text: Date of Application, 27th Apr., 188"
Complete Left, 26th Jan., 1888
Complete Accepted, 2nd Mar., 1888
I FREDERICK ALBERT GATTY of Hagg Works Accrington in the County of
Lancaster Dyer and Calico Printer do hereby declare the nature of said Invention for
IMPROVEMENTS IN DYEING COTTON YARNS AND FABRICS, to be as follows:-
My improvements consist in fixing Oxide of Chromium upon cotton yarns and
fabrics by forming Sulphate of Chromium upon the cotton materials and then
precipitating and fixing the Oxide upon such materials by means of an Alkali.
In carrying out my Invention the cotton yarns and fabrics are impregnated with a
solution of Bi-Chromate of Potash or Bi-Chromate of Soda and I then expose the
same to the action of Sulphurous Acid Gas until the Chromic Acid is deoxidised and is
transformed into Sulphate of Chromium. The materials are then preferably dried
and passed through a solution of an Alkali or Alkaline Salt in order to precipitate
and fix upon the materials the Oxide of Chromium after which the said materials are
washed.
.
If it be desired to fix upon the materials other metallic Oxides in combination with
the Oxide of Chromium I add a metallic salt containing the iesired Oxide to the
solution of the Bi-Chromate of Potash or Bi-Chromate of Soda and proceed in the
manner described.
The yarns or fabrics into or upon which the Oxide of Chromium either alone or in
combination with other metallic Oxides has been fixed may be dried and the Oxides
used either as self colours or as mordants for a subsequent dyeing process with
colouring matter such as Alizarine or dyewoods.

page_text: COMILVIE SIECIFICATION,
Improvements in Dyeing Cotton Yarns and Fabrics.
J FREDERICK ALBERT GATTY of Hagg Works Accrington in the County of
Lancaster Dyer and Calico Printer, 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 improvements consist in fixing Oxide of Chromium upon cotton yarns and
fabrics by forming Sulphate of Chromium upon the cotton materials and then
precipitating and fixing the Oxide upon such materials by means of an alkali.
If it be desired to fix upon the materials other metallic Oxides in combination with
the Oxide of Chromium add a metallic salt containing the desired Oxide to the
solution of the Bi-Chromate of Potash or Bi-Chromate of Soda and proceed in the
manner hereinafter described.
And in order that I may be fully understood I will proceed to describe the manner
in which I prefer to carry my Invention into effect.
After the yarns or fabrics have been boiled and freed from impurities they are
impregnated with a solution containing for every gallon of water from one to one and
a half pounds of Bi-Chromate of Soda or an equivalent quantity of Bi-Chromate of
Potash and from four to six ounces of Acetate of Soda or its equivalent Carbonate of
Soda or other Alkaline Salt for every pound of Bi-Chromate of Soda or Bi-Chromate
of Potash used.
After the excess of liquor has been squeezed out of the materials they are exposed
to the action of Sulphurous Acid gas until the Chromic Acid is deoxidised. In the
case of yarns they are hung upon rods or otherwise conveniently suspended in a
chamber filled with Sulphurous Acid gas obtained by burning sulphur or by any of
the known methods. For fabrics I find the most convenient way is to run them over
rollers through a chamber supplied with Sulphurous Acid gas as above described.
In order to vary the shades from the green to a brown colour I add to the solution
of Bi-Chromate of Soda or Bi-Chromate of Potash a certain quantity of a metallic
Oxide such as a Salt of Iron by preference Acetate of Iron or common Iron liquor.
The proportion of Iron Salt use obviously depends upon the colour require. For
example when a green shade is desired I use about one pint of Iron liquor at twenty
degrees of Twaddle's Hydrometer for every pound of Bi-Chromate of Soda or
Bi-Chromate of Potash while for brown shades I use from a quart to three pints.
After the Chromic Acid has been deoxidised which can easily be seen by its green
colour the materials are passed through an Alkali or Alkaline Salt such as Carbonate
of Soda but any Alkali which will precipitate the metallic Oxides will answer the
purpose. I prefer to use Caustic Soda at four to six degrees of Twaddle's Hydrometer
at a temperature of 140° to 160° Fahrenheit but stronger or weaker Alkali does not
affect the colour.
In the case of fabrics if the colours be dark and strong I prefer to dry them before
passing them through the Alkali.

page_text: The yarns or fabrics into or upon which the Oxide of Chromium either alone or in
combination with other metallic Oxides has been fixed may be dried and the Oxides
used either as self colours or as mordants for a subsequent dyeing process with
colouring matter such as Alizarine or dyewoods.
Having now particularly described and ascertained the nature of my said Invention
and in what manner the same is to be performed I would have it clearly
understood that I do not confine myself to the particular proportions or to exact
strengths of the substances or materials employed as they may be varied according to
the shades desired nor do I bind myself to the exact node or order of proceeding as
herein specified as the same may be varied or modified if found advantageous or
desirable without departing from the nature of my Invention but I declare that what
I claim is―
1.-Fixing upon cotton materials Oxide of Chromium either alone or in combination
with a metallic salt by impregnating the said materials with a solution of Bi-Chromate
of Soda or Bi-Chromate of Potash either alone or mixed with a metallic Salt such as a
Salt of Iron then subjecting the materials to the action of Sulphurous Acid gas until
the Chromic Acid is deoxidised and is also transformed into Sulphate of Chromium
and finally precipitating and fixing the Oxide by means of an Alkali.
2 The herein described improvements in dyeing cotton yarns and fabrics con-
sisting in fixing Oxide of Chromium either alone or in combination with an Iron Salt
upon cotton yarns or fabrics by forming Sulphate of Chromium upon the cotton
materials and then precipitating and fixing the Oxide upon such materials by means of
an Alkali.