Improvements in Rendering Canvas and other Fabrics Rot-proof.
Year: 1890

page_text: Date of Application, 11th Aug., 1890
Complete Specification Left, 8th June, 1891-Accepted, 11th July, 1891
PROVISIONAL SPECIFICATION.
Improvements in Rendering Canvas and other Fabrics Rot-proof.
JAMES WILLIAMS, Willesden Paper Works, Willesden Junction London N.W.
do hereby declare the nature of this invention to be as follows:-
To render canvas and other materials rot-proof and more durable than ordinary
untreated canvas without practically altering the natural colour, I impregnate the
fabric with sub-sulphocyanide of copper. This I effect by first soaking the fabric
to be treated in a solution of sulphate or other salt of copper, then drying, and
passing through a solution of any convenient sulphocyanide, such as the sulpho-
cyanide of ammonium and sulphurous acid, or a bisulphite. The sub-sulphocyanide
of copper is then formed in the fibres of the fabric as a whitish powder. In actual.
practice however, I prefer to pass the fabric through a bath of ammoniacal solution
of oxide of copper, as in the well known Willesden process, when the surface on
drying is covered with a green compound of hydrate of copper and cellulose. This
green compound is then acted upon by the before mentioned bath of sulphocyanide
of ammonium & sulphurous acid, or a bisulphite by which means the sub-sulpho-
cyanide of copper is formed; the cellulose with which it is associated aiding its
mechanical adhesion to the fibre.
Dated this Oth dow of 1000
JAMES WILLIAMS.
COMPLETE SPECIFICATION.
Improvements in Rendering Canvas and other Fabrics Rot-proof.
I, JAMES WILLIAMS, of Willesden Paper Works, Willesden Junction,
London, N.W., Chemist, 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:-
To render canvas and other materials rot proof and more durable than ordinary
untreated canvas, without practically altering the natural colour I impregnate the
fabric with sub sulpho cyanide of copper.
This I may effect by first soaking the fabric to be treated in a solution containing
from 10 to 20 per cent. of sulphate of copper or other salt of copper such as acetate
or chloride of copper then drying and passing through a solution of any convenient
sulpho-cyanide, such as sulpho-cyanide of ammonium and sulphurous acid; or a bi-
sulphite. The proportions I employ are approximately 60 lbs. of sulpho cyanide
of ammonium and 100 lbs. of sulphite of sodium to 100 gallons of water, and as the
fabric passes through the bath sufficient sulphuric acid is added to liberate enough
sulphurous acid from the sulphite of sodium as will reduce the copper contained in
the fabric to white sulpho cyanide, which is thus formed in the fibres of the fabric
as a whitish powder. A moderate excess of sulphuric acid does not injuriously
affect the working of the process, provided that a sufficient excess of sulphite of
soda remains in the solution to form bi-sulphite. In order to secure uniformity in
results it is desirable to add approximately sufficient of sulpho cyanide of
aminonium and sulphite of sodium to replace that decomposed by the copper
compound or the sulphuric acid as the case may be.
Instead of employing sulphurous acid, or a bi-sulphite to effect the reduction,
other suitable reducing agents could be used such as an acid solution of proto
sulphate of iron, or an acid solution of proto chloride of tin.
After the fabric has been sufficiently treated to ensure total conversion of the

page_text: copper into sub-sulpho cyanide of copper, I remove it from the bath and wash it by
means of its passage through a tank of running water, and finally dry it.
In actual practice however, I prefer to pass the fabric through a bath of
ammoniacal solution of oxide of copper, as in the well known Willesden process,
when the surface on drying is covered with a green compound of hydrate of copper
and cellulose the process is then completed as above described. In this case
cellulose with which the sub sulpho cyanide of copper is associated aids its
mechanical adhesion to the fibre.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is :-
1. Canvas or other fabric having its surface impregnated with sub sulpho
cyanide of copper.
2. The process of rendering canvas or other fabric rot proof by impregnating
its surface with sub sulpho cyanide of copper substantially as described.
Dated this 8th day of June 1891.
J. WILLIAMS.