A Process of Producing on Paper, Textile Fabrics, Wood, Leather, Skins, and other Light Materials a Transparent Waterproof Coating.
Year: 1887

page_text: PROVISIONAL SPECIFICATION.
A Process of Producing on Paper, Textile Fabrics, Wood, Leather,
Skins, and other Light Materials a Transparent Waterproof
Coating.
I FRANCIS HENRY FROEDMAN Pharmaceutical Chemist of Ireland 23 Mary Street
Dublin, Ireland do hereby declare the nature of this invention to be as follows:-
My invention consists of covering the above stated Materials, by suitable means,
with a Mixture of Gelatine, Glue or other colloidal bodies containing in solution a
certain proportion of a Chromium salt, either Bichromate of potash or ammonia, drying
and exposing to light, by means of which the so coated articles are first rendered
insoluble and then converting the so altered compound into a colourless transparent
Waterproof body by means of Sulphurous Acid or its compounds.
The Gelatine mixture may be made, according to the substance of Material to be
operated upon, either thick or thin, by modifying proportions of ingredients; but 1
have found the following answer for most purposes:
Take of Gelatine, 3 parts: Water, 24 parts; Solution Bichromate of potash
(six per cent), 4 to 8 parts; Spirit, & parts; Glycerine or Sugar, + part; Soak the
Gelatine in the Water and Bichrome solution, then heat on Water bath until dissolved,
lastly add the Spirit and Glycerine previously mixed; stir well and filter through
flannel.
The above stated Materials are coated by means of either a brush, or immersed, or
floated on the Gelatine mixture so as to produce an even thickness, then dried and
exposed to light to convert the Gelatine or other colloidal bodies so treated into an
insoluble compound; after which they are submitted to a Bath of Sulphurous Acid or
its compounds; which dissolves any unaffected Chromium salts and produces a
transparent almost colourless insoluble Waterproof covering. After the reaction of
the Sulphurous Acid Bath the articles have to be well washed to remove all acidity and
lastly dried.
Having now particularly described the nature of my invention and in what manner
the same may be performed, though I am aware that the process of rendering Gelatine
insoluble by means of Chromium salts is not unknown; but what I claim is that by
the action of Sulphurous Acid or its compounds as carried out in the manner described
above, it is converted into a transparent insoluble waterproof covering and I produce
results never before attained.
Dated this 19th day of January 1887.
FRANCIS HENRY FROEDMAN,
Pharmaceutical Chemist of Ireland.

page_text: COMPLETE SPECIFICATION.
A Process of Producing on Paper, Textile Fabrics, Wood, Leather,
Skins, and other Light Materials a Transparent Waterproof
Coating.
FRANCIS HENRY FROEDMAN Pharmaceutical Chemist of Ireland 23 Mary Street
Dublin Ireland 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 invention consists of covering the above stated Materials, by suitable means,
with a mixture of Gelatine, Glue or other colloidal bodies containing in Solution a
certain proportion of a Chromium salt, either Bichromate of potash or ainmonia,
drying and exposing to light, by means of which the so coated articles are first
rendered insoluble, and then converting the so altered compound into a colourless
transparent Waterproof body, by means of Sulphurous Acid or its compounds.
The Gelatine mixture may be made according to the substance of Material to be
operated upon, either thick or thin, by modifying proportions of ingredients, but I
have found the following answer for most purposes:
Take of Gelatine 3 parts, Water 24 parts, Solution Bichromate of potash (6%)
4 to 8 parts, Spirit 4 parts, Glycerine or Sugar part.
Soak the Gelatine in the Water and Bichrome Solution, then heat on a Waterbath
until dissolved, lastly add the Spirit and Glycerine previously mixed; stir well
and filter through flannel.
:
The above stated Materials are coated by means of either a brush, or immersed, or
floated on the Gelatine mixture so as to produce an even thickness; or the Gelatinous
mixture is spread on Glasses previously cleaned and French chalked and then the
Materials are evenly put on the surface of the Gelatine mixture, then dried and
exposed to light to convert the Gelatine or other Colloidal bodies so treated into an
insoluble compound; after which they are submitted to a Bath of Sulphurous Acid or
its compounds; which dissolve any unaffected Chromium salts and produces a
transparent almost colourless insoluble Waterproof covering. After the reaction of
the Sulphurous Acid Bath the articles have to be well washed to remove all acidity,
and lastly dried.
In the case where the above named Materials are spread on Glasses they can be
stripped from the Glasses after drying.
Having now particularly described and ascertained the nature of my said Invention,
and in what manner the same may be performed, though I am aware that the process
of rendering Gelatine insoluble by means of Chromium salts is not unknown; [
declare what I claim is
That by the action of Sulphurous Acid or its compounds as carried out in the
manner described above, it is converted into a transparent insoluble Waterproof
covering, and I produce results never before attained.
Dated this 22nd day of September 1887.
FRANCIS HENRY FROEDMAN,
Pharmaceutical Chemist of Ireland.