Year: 1896

page_text: Date of Application, 6th Oct., 1896--Accepted, 9th Jan., 1897
A communication by WILLIAM HENRY BRAWLEY, JOHN BUSSING COLES, and
CHARLES NATHANIEL COLES, Merchants, all of No. 24 Vesey Street, in
the City, County, and State of New York, United States of America.
1, WILLIAM PHILLIPS THOMPSON F.C.S., M.I.M.E., of The Agency for
Foreign Patent Solicitors, 6 Lord Street, Liverpool, and 6, Bank Street,
Manchester, both in the County of Lancaster, 118 New Street, Birmingham in
the County of Warwick and 322 High Holborn in the County of Middlesex, Civil
Engineer, 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 improvement in slating compounds adapted to
impart to the various substances or articles to which it is applied a surface capable
of being readily written upon by a lead pencil or a like instrument, the surface
being of such a nature that the marks made by writing or drawing upon the slated
surface may be conveniently and expeditiously expunged from the surface by the
use of water and a cloth, sponge, or the equivalent thereof.
A further object of the invention is to so improve upon the composition of this
nature as to produce a slated surface which will also be exceedingly smooth and
practically polished.
The invention consists in the combination of ingredients to be hereinafter fully.
set forth and pointed out in the claims.
In preparing this slating surface, alumina or cryolite (sodium aluminum fluoride)
(Na 3 AlF 6) which is united to the base by means of a solution of shellac made
either by means of an alkali in water or by means of alcohol, is employed. The
operation is as follows:-
To about one pound of shellac, preferably purified white shellac in gum form,
half a pound of borax and about one gallon of water are added and allowed to
dissolve. Preferably the solution is expedited by heating in a hot water bath.
The solution is then diluted with about half a gallon of water and half a pound of
alumina (Al,O,) or cryolite is added. The resulting liquid is applied as a first
coating to the cardboard, wood, tin or other inaterial forming the foundation of the
slate. This coated sheet is then allowed to dry. The paper or other slated
surface being now "filled" with the first coat is ready to act as a foundation for
the second slating coat. Before applying the second coat, it is preferable to
sand-paper or calender the paper or other first-coated material. The solution
for the second coat is prepared as follows:-One pound of white shellac is dissolved
in one-half a gallon of alcohol, and one-quarter of a pound of alumina or cryolite is
added and to this one quart of alcohol is added to reduce the same.
This applied
as a varnish to finish the sheet makes the same thoroughly waterproof.
The slating above-described can be used on cheap material without discoloring
it. Any suitable coloring matter may be added in case a black or other colored
surface is desired or it can be used as a transparent marking surface by omitting
coloring matter. The texture of the paper is not destroyed, the surface is smooth
and even; it will not crack; it may be written upon by lead pencil and the
writing or drawing erased without leaving trace of the marks and the inventors

page_text: have succeeded for the first time in making a slating surface thoroughly
waterproof.
The proportions.above stated may be varied considerably; proportions have
merely been stated which have been found efficient. Either pure grain alcohol or
wood alcohol may be used. The application of the coats may be by brush, by
machine or by dipping the sheets in tanks containing the solutions.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me by
my foreign correspondents, I declare that what I claim is :-
1. A slating compound comprising shellac, alcohol and alumina or cryolyte,
mixed in substantially the proportions and in the manner set forth.
2. A slating compound comprising a shellac solution and alumina or cryolyte, as
set forth.
Dated this 5th day of October 1896.
WM. P. THOMPSON & Co.,
Agents.