IMPROVEMENTS IN DYEING AND PRINTING WITH ANILINE COLORS
Year: 1869

page_text: PROVISIONAL SPECIFICATION left by John Henry Johnson at the
Office of the Commissioners of Patents, with his Petition, on the
4th March 1869.-A communication from abroad by Pierre Blumer-
Zweifel, of Paris, in the Empire of France.
"
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County
of Middlesex, Gentleman, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN DYEING AND PRINTING WITH ANILINE COLORS,'
communication to me from abroad by Pierre Blumer-Zweifel, of
Paris, in the Empire of France, to be as follows:-
This Invention relates to improvements in dyeing and printing with
what is known as aniline blue, by which an absolute purity of color
is obtained, and by modifications of the process various shades of color
may be produced.
The process consists in employing an acid bath in which the dyed
fabric is immersed either immediately after undergoing oxidation or
after the employment of an alkaline bath, the degree of concentration
or strength of the acid being regulated according to the fabric under
operation and the result it is desired to obtain. The intensity and
shade of the color will be dependent on the strength of the bath and

page_text: the proportion of acid employed, but care is to be taken not to employ
a bath in which the acid shall be in such quantity as that the fabric
will be injured. The duration of the operation together with the
temperature of the bath will depend upon the tint it is desired to
obtain. In practice it is found that the shade of color depends upon
the temperature of the bath, the color being heightened according to
the increased elevation of the temperature. The proportion of acid
may also be modified in proportion to the temperature of the bath
employed, the more elevated the temperature of the bath the smaller
is the proportion of acid necessary to be employed. Thus supposing,
for example, sulphuric acid be employed, which acid I prefer, a bath
marking about 2° Baume and employed at a temperature of about
158° Fahrenheit an immersion of about two minutes will heighten
and improve the tint of the ordinary colors, whereas in some cases
the proportion of acid may even be less according to the peculiar
composition of the dye. When the operation is completed the coloring
matter is washed and submitted to the action of an alkaline solution,
the effect of which is to change the green color into a new blue color.
These baths may be repeated if the change to be produced is too im-
portant to be effected in a single operation without injuring the fibre.
A similar result may also be arrived at by causing the acid to react
during the whole time of the oxidation preparing the fibre with
an acid or a combination which will liberate this acid by the effect of
a double decomposition which is effected when in contact with the
color, or instead thereof by emplying any very acid color. As the acid
in this case greatly accelerates oxidation it may to a certain extent
be replaced by any body possessing great oxidising power. The pure
blue tone may also be imparted to the color by the employment of a
salt of iron, which under the influence of oxidation passes into the
state of oxide of iron, which becomes attached to the fibre, and changes
by the employment of prussiate of potash into prussian blue. In order
to give solidity to the color a very small proportion of nitrate of
iron may be added. About double the quantity is required for printing
to that requisite for dyeing.