An Improved Method of and Apparatus for Preparing Copal and other Gum Resins and Resins and Manufacturing Varnish.
Year: 1890

page_text: Date of Application, 9th Apr., 1890
Complete Specification Left, 9th Feb., 1891-Accepted, 14th Mar., 1891
PROVISIONAL SPECIFICATION.
An Improved Method of and Apparatus for Preparing Copal and
other Gum Resins and Resins and Manufacturing Varnish.
1, ARTHUR FRENCH ST. GEORGE, of Redhill, in the County of Surrey,
Electrician, do hereby declare the nature of this invention to be as follows:-
:-
My invention relates more particularly to the treatment of copal and other hard
gum-resins which require a considerable degree of heat for fusion and solution in
oils or spirits.
The hard quality gum copal requires about 500° F. for fusion and much difficulty
has been experienced heretofore in combining it with drying oils to constitute a hard
oil varnish.
In order to render gum copal soluble in drying oil it has usually been found
necessary and it has been a practice in varnish manufacture to fuse the gum copal.
The fused copal (preferably ground to a powder after fusion) is then dissolved in
oil to form a varnish. It has been found that in the preliminary process of fusion
a large amount of copal is destroyed or dissipated as much as 25% being some-
times lost. It has also been a practice to add oil to copal in the fused condition
cautiously and with dexterity but considerable difficulty and loss has been
experienced according to this and other processes on account of the insolubility of
the copal.
In the process of fusion as ordinarily heretofore employed the gum copal is
discoloured or blackened and in combining it with the oil a dark varnish has usually
been the result.
According to my invention I render the copal soluble in oil without losing any of
the copal and without discolouring it. In order to put my invention in operation I
employ an apparatus consisting of a shallow pan or melting pot provided with a cover
which is fitted with a dome or capital provided with numerous tubes reaching to a
considerable height preferably about five times the height of the melting pot and
cold water jacketted or otherwise kept cool whilst in use. Or one large tube or
extension of the melting pot may be used. In the melting pan I put sufficient
granulated copal to fill about a third of its depth. In connection with the apparatus
arrange a still in such manner that vapours or liquid or spray from it shall pass
within the apparatus and there be condensed into a spray or liquid and fall upon
the gum in the pan.
I apply a brisk heat to the melting pan and fuse the copal and maintain the heat
preferably until a few minutes after the copal boils or bubbles and throws up liquid.
towards the tubes. The dense heavy white vapours of the fused copal rise under
pressure to a considerable height in the cooling tubes where they become condensed
and fall upon the gum below in a liquid or spray and combine with it. In the still
I place linseed oil or other liquid or substance affording similar acrid vapours of
distillation such as olive oil glycerine lard oil &c. I put the still in operation and
the vapours passing from it condense in the tubes and fall (in a similar manner to
or combined with the gum vapours) upon and into the gum. The vapours or liquid
from the still assist the process. The gum pan and still are heated and worked at
the same time and I prefer to continue passing the vapours from the retort to the
gum until the latter is about to solidify and cool. Gum copal and other hard
gums or resins treated by this method and apparatus of my invention are readily
fused without discolouration or scarcely any discolouration and without impairing its
useful properties. In all cases I employ a high temperature quickly applied to the gum
pan and the process takes usually from 15 to 20 minutes only and the
gum taken from
CD

page_text: the
pan when cool (and not until all the vapours have condensed or disappeared within
the apparatus) is readily soluble in oil or spirits in almost any relative proportions for
the purpose of manufacture of hard oil or spirit varnish or of other materials to
which the gum-resin may impart a useful property. In order according to my
invention to manufacture oil varnish I employ an apparatus consisting of a boiling
pot being a vertical cylinder closed at the bottom and of height about five or more
times the measure of its diameter. I provide the cylinder with a dome or capital
and cooling tubes and a still containing linseed oil and communicating therewith as
in the gum pan apparatus. In the cylinder I put the desired quantity of oil to be
combined with copal. I heat the cylinder and the still the former quickly to the
point of the simmering of the oil the latter to the point of vapours passing off.
then add through an orifice in the dome the desired quantity of copal. I maintain
the heating of the cylinder until the copal floats to the surface. I then increase
the heat until the oil rises and froths to about five times its former height and
sustain the heat for a minute or two until the copal has entirely combined with the
froth and oil and disappeared. I then withdraw the heat and allow it to cool. I
also cut off communication with the still and allow most of the vapours to condense
and fall down and combine with the varnish before drawing it off.
I
The operation of blending the oil and copal together according to my invention
as described is accomplished in 6 to 15 minutes with certainty and the oil is less
discoloured than in the processes as ordinarily heretofore employed and involves no
loss of material, danger or smell and is not detrimental to the health of the
operator.
In all cases according to my invention I employ the acrid vapours or distillates
of fats or oils affording acroline. The acrid vapours or distillates of linseed oil
being particularly useful in treating gun and blending it with linseed oil for making
oil varnish according to my invention.
Dated this 8th day of April 1890.
ARTHUR FRENCH ST. GEORGE.
COMPLETE SPECIFICATION.
An Improved Method of and Apparatus for Preparing Copal and
other Gum-resins and Resins and Manufacturing Varnish.
I, ARTHUR FRENCH ST. GEORGE, of Redhill, in the County of Surrey,
Electrician, 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 more particularly to the treatment of copal and other hard
gum resins and resins which require a considerable degree of heat for fusion and
solution in oils or spirits. The hard quality gum copal requires about 500° F. for
fusion and much difficulty has been experienced heretofore in combining it with
drying oils to constitute a hard oil varnish.
In order to render gum copal soluble in oils or spirits it has been a practice in
varnish manufacture to fuse the gum copal in a melting pot. I have observed that
in this preliminary process of fusion a large amount of copal is destroyed or
dissipated in vapours as much as 25% being sometimes lost and the copal remaining
in the melting pot is discoloured or blackened and in combining it with the oil a
dark varnish has usually been the result.
It has been usually the practice to grind the fused copal to a powder and then to
boil it with oil or spirits. It has also been a practice to add boiling oil or spirits
of turpentine to copal while in the fused condition with caution and dexterity but
considerable difficulty loss and danger has been experienced according to this and
other processes on account of the insolubility of the copal and its high melting
point the latter quality being an element of danger in adding spirits of turpentine

page_text: which sometimes fires or explodes at a lower temperature than the melting point of
the gum and many serious accidents have resulted therefrom.
According to my invention I render copal, amber, animé, kauri and other gum
resins and resins soluble in oil or spirits without losing any of the gum and without
discolouring it. I have discovered that all the gun resins ordinarily employed
in varnish manufacture which in the raw state are difficult to dissolve in oil or
spirits and are highly. infusible become readily soluble (and less infusible) in oils
or spirits by a preliminary process of digestion and fusion of the gum resin in its
own vapours of distillation preferably excluding air from contact with the same
during digestion.
And I have discovered that this preliminary process is sometimes assisted by the
presence of acrid vapours distilled from oils &c. in addition.
In order to put my invention in operation I employ an apparatus consisting of a
shallow pan or melting pot provided with a cover or dome fitted with tubes reaching
to a considerable height or distance preferably to about five times the height or
measure of the melting pot and cold water jacketed or otherwise kept cool while in
use. Or one large tube or an extension of the melting pot according to my
invention may be used.
In the melting pan I place sufficient granulated copal to fill about one third of its
depth. I apply a brisk heat to the melting pan and fuse the copal and maintain the
heat preferably until a few minutes after the copal boils or bubbles as a completely
clear fused mass and throws up liquid actively towards the tubes. In this process
of fusion and digestion the dense heavy white vapours of the fused copal rise under
pressure to a considerable height or distance in the cooling tubes where they
become condensed and fall upon the gum resin below in a liquid or spray and
combine with it. Distillation and recombination are repeatedly taking place and
such process produces such a change of condition of the gum resin (without losing
any gum) as to render it soluble in oils or spirits (or other solvents or menstrua)
and fusible. The process occupies usually from 15 to 20 minutes but the time must
be regulated by ordinary care and judgment always considering the particular
nature of the gum under treatment avoiding at the same time the risk of dis-
colouration by too long continued digestion. A quickly applied heat of about the
melting point of the gum is in most cases preferable. All vapours excepting
ordinary water dampness should be allowed to settle and combine before
opening the pan & removing the gum for use. I prefer to cool the gum down to
about 220° F. and then removing it from the pan any water dampness will pass off
and at about this temperature the gum may be most conveniently withdrawn in a solid
mass not having hardened sufficiently to adhere to the pan. To assist the digestion
and increase the solubility of some gum resins treated in the apparatus described
sometimes employ in connexion with the latter a retort supplying acrid vapours of
distillation from oils and fats that afford acroleine and oleic acid vapours. The
retort or still is so arranged that vapours or liquids or spray from it shall pass
within the gum digestion apparatus and there be condensed into a spray or liquid
and fall upon the gum in the pan. I prefer to distil the oleic or acrylic vapours
or residue from the gum before dissolving it as a varnish but this is not always
necessary for gums employed for purposes other than varnish manufacture.
In order according to my invention to manufacture oil varnish I employ an
apparatus consisting of a boiling pot being a vertical cylinder closed at the bottom
and in height about five or more times the measure of its diameter. I provide the
cylinder with a dome or cover fitted with cooling tubes and a retort or still
communicating with the apparatus as in the gum-pan apparatus.
In the cylinder I put the desired quantity of oil to be combined with gum resin.
I heat the cylinder to the point of simmering of the oil (and pass into the cylinder
acrid vapours of oil from the still if necessary). I maintain a brisk heat until the
copal floats to the surface.
I then increase the heat until the oil rises and froths to about three to five times
its former height and sustain the heat for a minute or two until the copal has

page_text: entirely combined with the froth and oil and disappeared. I then withdraw the
heat and allow it to cool and the vapours to condense and recombine before drawing
off the liquid solution of gum in oil.
This operation of blending the oil and copal together according to my invention
as described is accomplished in 6 to 15 minutes with certainty and the oil is less
discoloured than in the processes as ordinarily heretofore employed and the process
involves no loss of material danger or smell and is not detrimental to the health of
the operator. It is obvious that spirits of turpentine may according to my process
be combined with the gum as readily as oil. Driers may be added and impurities
or dampness removed according to any of the best accepted methods of the varnish
manufacturer.
C₂
DESCRIPTION OF THE DRAWINGS.
Figure 1. is the gum pan provided with an accurately fitted removable cover a¹.
is an inlet pipe and cock communicating with a retort or still. ; b, b, are cooling
tubes. is a furnace screened by the hood c for heating the gum pan a.
Figure 2. a, is the vertical boiler provided with cooling tubes a a¹ and gauge
glasses b, b, b, b for observation. a² is an inlet pipe and cock communicating with a
retort or still. " is a syphon tube for pumping off the solution. d, is the orifice
(closed by a screw plug) for admitting the raw gum. f is a gas furnace and conical
hood y enveloping the lower portion of the boiler for heating the same.
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. The treatment of gum resins or resins by digestion in their own vapours or
distillates or in-the-presence of the same substantially as and for the purposes
described.
2. In an apparatus for the treatment of gum resins or resins the combination of
a melting pot with cooling tubes or condensers or other suitable cooling extension
or device substantially as and for the purposes described and illustrated by the
accompanying drawing.
3. Said combination of a melting pot and cooling device together with a com-
municating still or retort for supplying vapours thereto substantially as and for the
purposes described.
4. The combination of a boiler with condensing tubes or other suitable condensing
extension or device substantially as and for the purposes described and illustrated
in the accompanying drawing.
5. Manufacturing oil or spirit solutions of gum resins or resins by treatment in a
boiler provided with condensing tubes or condensers or other suitable extension or
device substantially as described.
Dated this 9th day of February 1891.
ARTHUR FRENCH ST. GEORGE.