An Improved Process for the Manufacture of Varnish.
Year: 1899

page_text: Date of Application, 25th July, 1899-Accepted, 26th Aug.,
1899
COMPLETE SPECIFICATION.
An Improved Process for the Manufacture of Varnish.
I, AUGUST PHILIP BJERREGAARD, of 12, St. Andrews Place, Brooklyn, State of
New York, United States of America, 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:-
This invention relates to an improved process for the manufacture of those
varnishes which consist chiefly of linseed oil or other fatty oils and copal gums,
and by the term copal is included amber, which is simply a very hard and highly
fossilized copal, as well as the other gums known as copals, whether hard, semi-
hard or soft.
Heretofore in the manufacture of varnish composed chiefly of the above
elements, the steps have been as follows: First, the gum is fused in one receptacle
and the oil heated in another receptacle; Second, the hot oil is poured into the
fused gum and the mixture boiled until it responds to the desired test and then
allowed to cool.
The disadvantages of the above well-known and common process are manifold,
some of them being the necessity in making a good varnish, of employing only
the larger lumps of gum, while the finer lumps are discarded, for the reason that
the heat required to soften and fuse the larger lumps, would, if fine particles were
used, char or burn the latter and thereby result in injury to the color and quality
of the finished product; another disadvantage is, the necessity of the constant
and watchful attention of a skilled operator to prevent charring and burning
during the fusing or running process of the gum; another, the limited capacity
of the output of a single operator as compared with the capacity of output of the
same operator utilizing the improved process hereinafter described.
The chief objects of this invention are in general to simplify and make easier
the process of varnish-making, and to provide a process whereby particles of gum
in its raw state and of any degree of fineness may be utilized without the slightest
danger of burning the same, and thereby injuring the color and quality of the
finished product. By reason of the fact that the danger of burning the gum is
avoided, the operator is relieved of the necessity of guarding against that
particular cause of injury, and may occupy all his time attending to other details,
thus enabling a greater production of the finished product by a given number
of skilled operatives, than can be made by the old process. Further, where it is
customary by the old process to make the varnish in comparatively small batches,
the size of the batch made by this process is limited only by the capacity of the
apparatus used, which may be as large as desired, as distinguished from the
limited capacity of a feasible apparatus used under the old process.
In carrying out this invention, first mix raw copal gum with linseed or other
suitable fatty oil in the proportion for instance of about four (4) pounds of copal
to one (1) gallon of oil for a wearing body or outside surface varnish, but the
proportions are subject to variation according to the kind and quality of the gum
and oil used, or varnish to be made. They are about the same as they would be

page_text: in the ordinary process under similar conditions, and are to be determined with
more exactness by the judgment of a skilled operator whose experience in the old
process will guide him equally well in this. The gum is, preferably, finely ground
(although lumps may be used) and the oil is preferably unboiled. The mixture
is placed in a suitable kettle and subjected to heat which soon softens the gum
and at first imparts to it a tendency to rise to the surface, and if the kettle is an
ordinary one the gum should then be pressed or kept under the surface by any
suitable means. After the gum is sufficiently softened or quite melted by the
heat, the mass should be thoroughly stirred to mix the ingredients, as well as
to facilitate the escape of the vapors generated, the heating being meanwhile
continued until the ordinary tests applied to samples show that it has been
sufficiently boiled, and then the heating is stopped and the varnish is allowed to
cool naturally or artificially. It is then thinned as desired with turpentine or
other suitable thinning agent in the usual manner.
ILLUSTRATIVE EXAMPLE.
Take for instance, 60 lbs. ground kauri gum and mix it with 15 gals. raw
linseed oil. Gradually heat this mixture in a suitable vessel until the kauri
becomes fluid which will occur at about 350 degrees F. Next, heat the mixture
at an increased temperature until the liquid shall respond to a satisfactory varnish
test, which will occur at about 600 degrees F. During the latter part of the
heating, it is desirable to stir the mass as previously described. When the
varnish is completed, cool and thin the mass in the manner hereinbefore described.
The temperatures specifically mentioned are only relative and may vary substan-
tially, yet, anyone skilled in the art will by following the directions herein given,
produce in a simple, safe and effective manner, a satisfactory product. The time
required to carry out this process may vary greatly depending upon the area of
heating surface relative to the quantity of the material acted upon, and the
intensity of the heat employed.
Although good results are obtained in this process with oil that has been pre-
viously boiled, experience nevertheless has taught, that if the oil previously to
the mixing with the raw gum been too much boiled, as shown by the results,
more or less of a gelatinous or soft rubbery mass is apt to be produced, which
tends to impair the product, or render it entirely unfit for varnish. Therefore
to avoid all risk of failure, it is preferable to use oil that at the beginning of the
heating is entirely unboiled, as it will be found that by the time the gum has
become properly incorporated with the oil, the boiling of the latter is sufficient,
although if it is desired to make a thicker varnish the boiling may be still further
continued.
+
Any means that will ensure the quick melting and thorough mixture of the
gum in the oil before the latter is too much boiled will, with a proper continuation
of the heating, after said melting and mixing (which any one skilled in the old
process can judge of) ensure the success of the operation.
To reduce the varnish to a suitable consistency to enable it to be applied with
a brush, turpentine or other suitable thinning agent may be added thereto in the
ordinary manner.
As it is generally desirable to increase the drying properties of varnishes; a dryer
may be added, for example, in the following manner:
After the varnish has been thinned and cooled, add a very small quantity
(say 20 of 1% by weight) of litharge and its corresponding chemical equivalent
of precipitated borate of manganèse, and then stir the mixture well for 3 or 4 hours
until the drying properties have become sufficiently developed by the chemical
reactions which take place. Where the varnish has been made with an oil other
than a drying oil, then the amount of dryer added should be greater, and the
additional quantity required can be determined by tests.
Instead of mixing the gum and oil together cold and heating them simul-
taneously, it is practicable to make the varnish by first heating the oil, next

page_text: gradually introducing the cold gum into the hot oil, thus melting it therein, and
then heating the mixture until it responds to the desired tests.
The term fatty oil as used herein is meant to include any fatty oil from which,
in combination with copal, a varnish can be produced that can be made to dry.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
The process of making varnish of copal gum and fatty oil, said process con-
sisting in mixing a raw copal gum in a suitable fatty oil, next applying heat
until the gum in the oil becomes fused, and next applying an increased degree
of temperature until the mixture becomes varnish.
FELL & JAMES,
Agents for the Applicant.