Improvements in the Manufacture of Copal Varnish and other like Varnishes, and Solvents applicable therefor.
Year: 1899

page_text: Improvements in the Manufacture of Copal Varnish and other like
Varnishes, and Solvents applicable therefor.
I, SAMUEL BANNER, of 8, Fazakerley Street, Liverpool, in the County of
Lancaster, Oil Merchant, 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 :-
In making varnish from copal asphalt or the like, such material has to be
heated to about 600 degrees Fahrenheit, in order to fuse it, linseed oil
is then added and boiled with it in the usual way and afterwards solvents have
to be added. Now if light solvents be added at this temperature a very large
amount of these are volatilized and fly off, instead of combining, causing not merely
great loss but danger, on account of fire. If on the other hand solvents of high boiling
point are added instead, they take a very long time to dry, and the varnish becomes
unsaleable.
Now my invention is designed to enable me to add light volatile solvents at ordinary
atmospheric temperature, and yet have a high flash test, and avoid the loss and danger
incurred in the old process.
I take the copal asphalt and the like, fuse the same and add linseed oil in the usual
way. After sufficient boiling I cool the mass down to say 240 to 270 degrees Fahren-
heit, without its solidifying, I then add a hydrocarbon preferably of the olefine
parafine or terpene series having a boiling point a trifle above this temperature, and
cool down to the atmospheric temperature. If there be any sign of solidifying, I add
during the cooling, a little more of the aforesaid or other suitable hydrocarbon to the
mixture. The amount of hydrocarbon required for each variety of gum can be found
in this way without loss, the material being added a little at a time so as to prevent
the mass going solid until the required temperatures are reached. When the
material has been brought down to atmospheric temperature or thereabouts I add a
mixture of comparatively high and low boiling point hydrocarbons preferably of at
least two series in about equal quantities having the required flash point. This flash
point and the specific gravity of the mixture will be found to be above the average or
mean flash point and specific gravity of the various hydrocarbons forming the mixture
and in this way I can add a very large amount of light hydrocarbons, which themselves
would be below the Government test, and yet the flash point of the mixture will be above
that test, and at the same time I obtain a inuch better solvent, and a better drier than by
the ordinary process. These hydrocarbons are preferably a mixture of parafines, olefines
and sometimes terpines and are in quantity from 30 to fifty per cent. of the weight of
gums originally employed. This plan of forming a quick drying and excellent solvent
above Government test has I believe never before been known or used, though solvents
of different boiling points have been added erratically during the manufacture of
varnish.

page_text: 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 manufacture and use of copal and other varnishes which consists of the
addition to the fused gum or asphalt at different temperatures successively of linseed
oil and solvents, each in succession of a lower boiling point, so as to enable the
varnish to arrive at ordinary atmospheric temperature without solidifying, and then
adding a mixture of hydrocarbons of comparatively high and low boiling point, this
mixture having a higher flash point and specific gravity than the mean or average of
its constituents whereby light hydrocarbons can be added without danger or loss, and
a better solvent and drier obtained.
2. In the manufacture and use of copal or the like varnish, forming the varnish
with a solvent or solvents of comparatively high boiling point so as to be still liquid
or viscid at ordinary temperatures, and then adding a mixture of hydrocarbons such
as described to the material.
3. The copal or other varnish, substantially as herein described.
4. A solvent formed of hydrocarbons having varying flash-points combined together
in such a manner that the flash points of the combination shall be higher than the
mean of the various ingredients, substantially as described.
Dated the 28th day of April 1999.
ADI
W. P. THOMPSON & Co.,
Of London, Liverpool, Manchester, and Birmingham.