Year: 1899

page_text: I, OLIVER IMRAY, of Birkbeck Bank Chambers, Southampton Buildings, in
the County of London, Chartered Patent Agent, do hereby declare the nature
of this invention (as communicated to me from abroad by Gustav Roland and
Fritz Peterhauser, both of Hoechst a/Main, in the Empire of Germany, Chemists,)
to be as follows:-
It is well known that a simple and safe process for removing colour from
woollen rags and shoddy is much wanted in the textile industry as the demand
for light or undyed rags greatly surpasses the supply of these and no simple
and cheap process for the decoloration of rags without injuring the fibre has
hitherto been found.
27
My foreign correspondents have succeeded in finding an excellent means for
this purpose in the acid hydrosulphite, a product of reaction of zinc dust
upon bisulphite, which, when employed in an aqueous solution at boiling tem-
perature destroys the colour of the woollen rags after a short immersion.
Of the hydrosulphite solution only a comparatively small quantity is. required
and with most of the rags especially that of cloth, stockings, and woollen fabrics
generally a thorough decoloration is obtained, so that the goods manufactured
therefrom appear almost "white" as if manufactured from fresh wool.
As with this process the solidity, the touch and elasticity of the wool fibre
is in no way injured, there is obtained by the means described an improve-
ment of the rag material furnishing regenerated wool, which constitutes a
technical result of considerable importance.
EXAMPLE.
;
100 kilos. of fully dyed rags (bordeaux, scarlet red, navy blue, green), so-
called "Thibet," are boiled with about 1500 to 2000 litres of water and 100
to 150 litres of hydrosulphite solution, the rags being from time to time turned
to enable the liquid to thoroughly penetrate them. After boiling for about half
an hour the process is complete the rags having become nearly white. They
are then washed in a cold bath, dried and ready for manufacture.
The hydrosulphite solution is prepared by diluting 20 litres of sodium bisul-
phite of 38° Bé. specific gravity with 180 litres of water at 30°-40° C. and
adding gradually 4 kilos of zinc dust, while the mixture is well stirred. After
the reaction is complete, the whole is allowed to rest and the clear supernatant
liquid is employed. Instead of sodium bisulphite potassium or ammonium
bisulphite may be used.
Instead of the 'separately prepared hydrosulphite solution the bisulphite and
zinc dust may be added directly to the bath, but this method is not to be recom-
mended as the material is soiled by the zinc dust.

page_text: The rags may be boiled either in an open or closed receiver; in the latter
case less hydrosulphite is required, but with the same result.
Dated this 21st day of July 1899.
ABEL & IMRAY,
Agents for the Applicant.
A Frocess for Decoloration of Rags and Shoddies.
I, OLIVER IMRAY, of Birkbeck Bank Chambers, Southampton Buildings, in
the County of London, Chartered Patent Agent, do hereby declare the nature
of this invention (as communicated to me from abroad by Gustav Roland and
Fritz Peterhauser, both of Hoechst a/Main, in the Empire of Germany, Chemists,)
and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement:-
It is well known that a simple and safe process for removing colour from
woollen rags and shoddy is much wanted in the textile industry as the demand
for light or undyed rags greatly surpasses the supply of these and no simple
and cheap process for the decoloration of rags without injuring the fibre has
hitherto been found.
My foreign correspondents have succeeded in finding an excellent means for
this purpose in the "acid" hydrosulphite, a product of reaction of zinc dust
upon bisulphite, which, when employed in an aqueous solution at boiling tem-
perature destroys the colour of the woollen rags after a short immersion.
Of the hydrosulphite solution only a comparatively small quantity is required
and with most of the rags especially that of cloth, stockings, and woollen fabrics
generally a thorough decoloration is obtained, so that the goods manufactured
therefrom appear almost white as if manufactured from fresh wool.
66
As with this process the solidity, the touch and elasticity of the wool fibre
is in no way injured, there is obtained by the means described an improve-
ment of the rag material furnishing regenerated wool, which constitutes a
technical result of considerable importance.
EXAMPLE.
100 kilos. of fully dyed rags (bordeaux, scarlet red, navy blue, green), 80-
called Thibet," are boiled with about 1500 to 2000 litres of water and 100
to 150 litres of hydrosulphite solution, the rags being from time to time turned
to enable the liquid to thoroughly penetrate them. After boiling for about half
an hour the process is complete the rags having become nearly white. They
are then washed in a cold bath, dried and ready for manufacture.
The hydrosulphite solution is prepared by diluting 20 litres of sodium bisul-
phite of 38° Bé. specific gravity with 180 litres of water at 30°-40° C. and
adding gradually 4 kilos of zinc dust, while the mixture is well stirred. After
the reaction is complete, the whole is allowed to rest and the clear supernatant
liquid is employed. Instead of sodium bisulphite potassium or ammonium
bisulphite may be used.
Instead of the separately prepared hydrosulphite solution the bisulphite and
zinc dust may be added directly to the bath, but this method is not to be recom-
mended as the material is soiled by the zinc dust.
The rags may be boiled in either an open or closed receiver; in the latter
case less hydrosulphite is required, but with the same result.

page_text: 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:
The herein described process for the decoloration of rags and shoddies, by
treating them at a boiling or lower temperature with hydrosulphite, the product
of reaction of zinc dust upon alkali bisulphite, or with zinc dust and alkali
bisulphite.
Dated this 28th dor of March 1000
ABEL & IMRAY,
Agents for the Applicant.