A New or Improved Protective Paint.
Year: 1893

page_text: Date of Application, 16th Oct., 1893-Accepted, 25th Nov., 1893
COMPLETE SPECIFICATION.
A New or Improved Protective Paint.
I, THEODOR COHN, of 70 Cottbusserdamm, Berliu, and Badenburger Mill, near
Giessen, both in the Empire of Germany, Manufacturer, 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 :-
The present invention relates to a new or improved protective paint, which, on
account of its great lightness and of its yielding character, remains elastic for a
considerable time and is therefore not easily affected by the expansions and con-
tractions of the material to which it is applied caused by variations of temperature,
and consequently cracks, which would destroy the utility of the protective paint,
cannot occur. Another advantage of the protective paint is that the latter, under
certain conditions, deposits an oily layer on the inner side of the coat of paint, i.e.,
on the surface which it is intended to protect by the paint. This layer, to a
considerable extent, increases the efficiency of the protective paint.
The improved protective paint consists mainly of oxide of lead, common salt,
and of a soluble salt of a suitable heavy metal, the whole being stirred up with a
little water and washed and finally ground with oils or varnish.
The effect of this paint may be explained by the following statement.
The oxide of lead combines with the common salt and forms chloride of lead and
hydrate of soda. The latter precipitates the oxides or the hydrates of the heavy
metallic salts and thereby forms, with the fatty acids contained in the oils.or
varnish, saponaceous products. The latter products become dissolved in the free
oil and give the paint its elasticity.
In practice I prefer to use the following materials combined in the proportions
stated ;-
10 parts of oxide of lead are mixed with
2 parts of common salt and stirred up with enough water to
form a thin paste. During the grinding or afterwards, about five parts of chloride
or sulphate of zinc is added and the whole washed with water, after which the
product is directly (without previously drying it) ground up with oils or varnish
into the proper consistency for painting.
To produce various colored paints the before named salts of zinc may be replaced
by other soluble salts, such as salts of copper, iron, chrome, manganese, cobalt or
nickel, according to the tint desired. In this manner the copper produces a green,
the chrome a grey-green, and manganese a brown tint; the above mentioned
quantity of the heavy metal can be increased if a paint of a deeper or stronger
colour is to be produced.
The proportions of the materials to be used depend on the nature of the latter
and the proportion of oxide of lead to common salt may be varied according to
requirements.
The paint may be applied to all kinds of material, but it is especially suited for
protecting metals and wood.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
An improved protective paint consisting of oxide of lead, common salt and the
soluble salt of a heavy metal, especially sulphate of copper, the whole mixed up

page_text: with a little water and then ground with oils or varnish, substantially as herein
described.
Date teh
tahan 1002
THEODOR COHN,
By Harris & Mills,
23, Southampton Buildings, London, W.C., Agents.