Treatment of Linseed and other Oils employed in Varnishes.
Year: 1890

page_text: Date of Application, 11th July, 1890
Complete Specification Left, 11th May, 1891--Accepted, 11th Aug., 1891
PROVISIONAL SPECIFICATION.
Treatment of Linseed and other Oils employed in Varnishes.
I ARTHUR FRENCH ST. GEORGE of Redhill in the County of Surrey,
Electrician and Chemist do hereby declare the nature of this invention to be
as follows:-
My present invention relates to the treatment of linseed oil and other oils
employed as varnishes so as to produce of the oil a colourless or almost colourless
varnish (which may be mixed with gum resins &c. if desired).
According to the method of treatment of linseed oil as ordinarily heretofore
employed it has not been found possible to produce a drying oil varnish other than
of a decided red, brown or deep yellow colour by reason of boiling, addition of
"driers and other treatment which discolour the oil in imparting to it the
necessary increased drying properties.
"
It has heretofore been proposed to bleach linseed drying oil but according to the
methods which have been devised the tenuity elasticity and toughness of the oil as
a varnish have been impaired or destroyed by the bleaching action or by the
reagents or methods employed.
According to my invention I take linseed oil in the raw state or preferably
cleansed of impurities and I deprive it of its colour and at the same time and by
the same process impart to it increased drying properties the result being a
colourless drying oil and by prolonging the process I produce a thick oil of the
consistency of (or thicker than) treacle void of colour and drying as quickly as 5
or 6 or 8 hours. In order to put my invention in operation I take the linseed oil
preferably cleansed of impurities and containing a small quantity of metallic oxide
such as lead oxide and 1 float it upon the surface of water containing ten volumes
of hydrogen peroxide preferably in shallow trays or pans. I place the oil thus
arranged in a chamber heated to such a temperature as not injuriously to affect the
oil and not sufficient to cause the hydrogen peroxide to be suddenly decomposed or
to explode. I find the best temperature to range between 90° F. and 210° F. By
the action of a gentle heat extended over a considerable time gas or vapour is
evolved and a reaction takes place gently gradually and thoroughly which deprives
the oil of its colour and imparts to it increased drying properties and its tenuity,
toughness and elasticity are not impaired but improved.
prefer to extend the process over several days at as low a temperature as
the process will allow of in order to ensure perfect decolorisation of the oil and to
impart extra increased drying properties to it and to thicken it so as to constitute a
thick oil varnish without colour. I do not according to my invention confine
myself to the use of hydrogen peroxide as other reagents may be used such as
chlorate of potash, manganese oxide, chromic acid &c. solid or in solutions and
preferably those reagents which conveniently evolve oxygen, hydrogen or carbonic
gas or vapours and pure water or water impregnated with carbonic gas or lime
may be employed with more or less success and by longer or shorter treatment
according to my invention. Neither do I confine myself to the use of a hot
chamber as I sometimes treat the oil by laying it out in an ordinary room at the
common temperature say 60° F. exposed for weeks or months and in all cases
prefer to carry on my process in daylight or by aid of electric light. My process
is applicable to the bleaching of oils containing gum resins in solution.
Dated this 10th day of July 1890
I

page_text: COMPLETE SPECIFICATION.
Treatment of Linseed and other Oils employed in Varnishes.
I, ARTHUR FRENCH ST. GEORGE, of Redhill, in the County of Surrey,
Electrician and 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:-
My invention relates to the treatment of linseed oil and other oils such as nut
oils employed in the manufacture of varnishes and the mixing of paints or pigments,
and has for its object to render the oil colourless or almost colourless and to adapt
it for use as a varnish with or without the addition of gum resins.
According to the method of treatment of linseed oil as ordinarily heretofore
employed it has not been found possible to produce a drying oil varnish other than
of a decided red, brown or deep yellow colour by reason of boiling, addition of
"driers" and other treatment which discolour the oil in imparting to it the
necessary increased drying properties.
It has heretofore been proposed to bleach linseed drying oil but according to the
methods which have been suggested to attain this end the tenuity, elasticity and
toughness of the oil as a varnish have been impaired or destroyed by the bleaching
action or by the reagents or methods employed, and in the case of edible and
illuminating oils their properties have been impaired or destroyed.
According to my invention I take linseed oil in the raw state or preferably
cleansed of impurities and I deprive it of its colour and at the same time and by
the same process impart to it increased drying properties the result being a
colourless drying oil and by prolonging the process I produce a thick oil of the
consistency of (or thicker than) treacle, devoid of colour and which will dry in
from 5 to 8 hours, and I attain this end by exposing the oil to be treated to a
gentle heat while floating upon or in contact with a re-agent capable of exerting a
bleaching, an oxydising or deoxydising or a cleansing action on the oil.
In practice I find it advantageous to take linseed oil preferably cleansed of
impurities and containing a small quantity of metallic oxide such as lead oxide and
I float it upon the surface of water containing ten volumes of hydrogen peroxide
preferably in shallow trays or pans. In this condition the oil is placed in a
chamber heated to such a temperature as not injuriously to affect the oil and
not sufficient to cause the hydrogen peroxide to be suddenly decomposed or. to.
explode.
I find the best temperature for this purpose to range between 90° Fahrenheit
and 210° Fahrenheit. By the action of a gentle heat extended over a considerable
time gas or vapour is evolved and a reaction takes place gently, gradually and
thoroughly, which deprives the oil of its colour and imparts to it increased
drying properties and its tenuity, toughness and elasticity are not impaired but.
improved.
I prefer to extend the process over several days at as low a temperature as the
process will admit of in order to ensure perfect decolorisation of the oil and to
impart extra increased drying properties to it and to thicken it so as to constitute a
thick oil varnish practically without colour.
Although I have described the use of hydrogen peroxide for carrying out my
invention I do not confine myself to the use of hydrogen peroxide as other re-agents
may be used such for example, as chlorate of potash, manganese oxide and chromic
acid either in a solid state or in solution and preferably I employ those re-agents
which conveniently evolve oxygen. I can also employ hydrogen or carbonic acid
gas or vapours or pure water, or water impregnated with carbonic acid gas or lime,
with more or less success and by longer or shorter treatment. Instead of making
use of a hot chamber as above named, I sometimes treat the oil by laying it out in
an ordinary room at the common temperature say 60° Fahrenheit exposed for weeks

page_text: or months but in all cases I prefer to carry on my process in daylight or by aid of
electric light. My process is also applicable to the bleaching of oils containing
gum resins in solution, or oils for illuminating purposes or for food.
A heating chamber suitable for use in carrying out my invention is shewn in the
accompanying drawing, in which :-
Figures 1 and 2 are a sectional elevation and horizontal section of the said
heating chamber.
a, a indicate the walls of the heating chamber proper and b, b the doors for
affording access to the said chamber. c indicates a covering of wood or other
suitable non-conducting material for enabling the heat within the chamber to be
maintained as uniform as possible, and d, d are doors.
e, e are steam pipes by means of which the chamber is heated, the said pipes
being extended through the chamber to form shelves or racks upon which the trays
can be placed. f.f indicate the said trays.
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 :-
1. The treatment of oils (or oils containing gum resin in solution) by exposing
the oil to a gentle heat while floating upon or in contact with a re-agent capable of
exerting a bleaching, an oxydising or deoxydising or a cleansing action on the oil
as and for the purposes set forth.
2. The use in the treatment of oil in the manner referred to in the preceding
claiming clause of apparatus constructed substantially as hereinbefore described and
illustrated in the accompanying drawing.
Dated the 11th day of M. 1901
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.