Improvements in the Manufacture of Writing-tablets.
Year: 1893

page_text: Date of Application, 14th Mar.; 1893
Complete Specification Left, 30th Mar., 1893-Accepted, 10th June, 1893
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Writing-tablets.
I, HEINRICH CHRISTIAN REINHOLD, Manufacturer of Hamburg-Barmbeck,
Heitmannstrasse No. 27 Germany do hereby declare the nature of this invention to
be as follows:-
Many attempts have been made to produce a writing-tablet capable of being
used as a
cheap and efficient substitute for the expensive and easily breakable
slate tablets heretofore used.
For this purpose writing tablets of enamelled sheet metal have been proposed
but a writing tablet of this kind has many disadvantages.
Thus the surface of such a tablet becomes in a short time so smooth that pencils
can no longer be caused to mark thereon, but slip and produce scratches which
cannot afterwards be easily removed. This drawback is due to the fact that in
the production of a dull dead or frosted surface by etching or by means of a sand-
blast as heretofore proposed, the crust or outer part that is to say the hardest part
of the enamel is removed, and the resulting relatively soft surface is in a short
time rubbed smooth by the frequent cleansing of the surface, the material
transferred from the pencil to the writing surface when writing, also acting as a
grinding agent when cleansing the said surface.
Now this invention has for object to manufacture writing tablets of enamelled
sheet or plate metal in such a manner as to obviate the disadvantage above
referred to. For this purpose cast iron plates or rolled sheets of iron, copper,
brass or the like, of any suitable size shape and thickness are carefully enamelled
in the usual manner with enamel containing in addition to the usual materials, an
addition of oxide of zinc say up to 38% The plates thus coated with enamel
are then placed in an enamelling furnace or oven and burned, whereby the zinc
oxide is separated, and the enamel caused to acquire a dead colour and surface so
that the plate can be used directly as a writing tablet.
In order to provide these tablets with lines, they may be ruled with any suitable
hard substance or composition such as a diamond or a pin or needle of hardened
steel.
In addition to the advantage of durability, writing tablets made as described
have a deep black writing surface, whereas with the frosting operations heretofore
employed even deep black surfaces are caused to become grey and now as writing
on a deep black surface can be more easily. read than on a grey surface tablets
made as described, are much less fatiguing to the eyes than those heretofore
proposed.
Duted this 14th day of March 1893.
H. KEINHOLD,
By L. W., per F. B.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Writing-tablets.
I, HEINRICH CHRISTIAN REINHOLD Manufacturer of Heitmanstrasse No. 27
Hamburg-Barmbeck, Germany 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 :-
Many attempts have been made to produce a writing-tablet capable of being

page_text: used as a cheap and efficient substitute for the expensive and easily breakable slate
tablets heretofore used.
For this purpose writing tablets of enamelled sheet metal have been proposed
but a writing tablet of this kind has many disadvantages.
Thus the surface of such a tablet becomes in a short time so smooth that
pencils can no longer be caused to mark thereon, but slip and produce scratches
which cannot afterwards be easily removed. This drawback is due to the fact
that in the production of a dull dead or frosted surface by etching or by means of
a sand-blast as heretofore proposed, the crust or outer part that is to say the
hardest part of the enamel is removed, and the resulting relatively soft surface
is in a short time rubbed smooth by the frequent cleansing of the surface, the
material transferred from the pencil to the writing surface when writing, also
acting as a grinding agent when cleansing the said surface.
Now this invention has for object to manufacture writing tablets of enamelled
sheet or plate metal in such a manner as to obviate the disadvantage above
referred to. For this purpose cast iron plates or rolled sheets of iron, copper,
brass or the like, of any suitable size shape and thickness are carefully enamelled
in the usual manner with enamel containing in addition to the usual materials such
as quartz, red lead, calcined soda, boracic acid, carbonate of cobalt hydrated iron
exide and peroxide of manganese, an addition of oxide of zinc say up to
about 38% of the weight of the said mixture of materials. The plates thus
coated with enamel are then placed in an enamelling furnace or oven and burned
in the usual way and at the temperature usually employed for enamelling, whereby
the zinc oxide is separated, and the enamel caused to acquire a dead color and
surface so that the plate can be used directly as a writing tablet.
In order to provide these tablets with lines, they may be ruled with any suitable
or hard substance or composition such as a diamond or a pin or needle of hardened
steel.
In addition to the advantage of durability, writing tablets made as described
have a deep black writing surface, whereas with the frosting operations heretofore
employed even deep black surfaces are caused to become grey and as writing on a
deep black surface can be more easily read than on a grey surface, tablets made as
described, are much less fatiguing to the eyes than those heretofore proposed.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
The herein described improvement in the manufacture of writing tablets of the
kind herein referred to which consists in adding zinc oxide to the enamel employed
for enamelling sheet or plate metal of suitable shape size and thickness, for the
purpose of producing directly by burning, a dead surface suitable for writing
purposes substantially as described.
Dated this 30th day of March 1893.
H. C. REINHOLD,
By L. W., per F. B.