Improved Writing Boards, and Process of Producing the same.
Year: 1895

page_text: Date of Application, 3rd Aug., 1895
Complete Specification Left, 2nd May, 1896-Accepted, 6th June, 1896
PROVISIONAL SPECIFICATION.
Improved Writing Boards, and Process of Producing the same.
I, HERMANN CAMPE of Nieder-Schönhausen near Berlin in the Kingdom of
Prussia, German Empire, Merchant, do hereby declare the nature of this invention
to be as follows :-
In order to produce white writing boards or plates, on the one hand sheet metal
plates have been coated with a layer of white enamel, the surface of which is
artificially roughened or dimmed, while on the other hand it has been endeavoured
to provide paste board plates with a white and sufficiently rough surface suited for
the adhesion of graphite or other pencil by applying thereon a layer of a compound
of water-glass and zinc-oxide with an addition of silicic magnesia. Writing boards
obtained by the former process, that is to say by enamelling sheet metal plates,
are unsuitable owing to.the brittleness of the enamel surface and owing to the fact
that the surface becomes smooth by use. Similarly with writing boards, obtained
by coating paste-board plates with a layer of the before-mentioned compound,
an uneven and extremely rough surface of insufficient resistance is produced while
moreover the layer will adhere imperfectly to the sheet metal and will readily.
crack.
The present invention succeeds in obtaining a sheet metal plate with a uniform,
strongly adhesive and resistible coating, having a very even and slightly roughened
surface and thus suitable for use in schools, and for writing purposes in general, by
proceeding in the following manner which is given as an example:
To one litre of water-glass, preferably natrium water-glass of 33 degrees Beaumé,
is added an emulsion of silicic acid obtained by stirring about 4 grammes of finely
pulverized silica, in % of a litre of water and allowing the same to settle for a short
After well
time and subsequently pouring the emulsion from the sediment.
stirring, the mixture is diluted with about of a litre of rain-water, then about
180 grammes of finely powdered carbonate of lime is added and well mixed there-
with and finally the whole is mixed with 600 grammes of zinc-white and ground in
a colour mill into a uniform, fine pulp of creamy appearance.
Into this mass the sheet metal plates previously carefully cleaned are dipped,
and subsequently dried, which drying process requires about 12 to 15 hours at a
temperature of from 15 to 20 degrees Réaumur. After the drying process the
plates are once more dipped, dried again and are then ready for framing.
The coating or layer produced in this manner, exhibits an agreeable, faintly blue
tint. It has great adhesive capacity rendering a special priming superfluous, and
moreover has a dimmed or frosted surface which takes the writing well; the same
is moreover so resistible that writing plates manufactured in this manner may
be roughly handled without injury to the coating and without causing the coating
to peel off.
Dated this 2nd def Aurust 1905
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.

page_text: Improved Writing Boards, and Process of Producing the same.
I, HERMANN CAMPE of Nieder-Schönhausen near Berlin in the Kingdom of
Prussia, German Empire, 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 order to produce white writing boards or plates, on the one hand sheet metal
plates have been coated with a layer of white enamel, the surface of which is
artificially roughened or dimmed, while on the other hand it has been endeavoured
to provide paste board plates with a white and sufficiently rough surface suited for
the adhesion of graphite or other pencil by applying thereon a layer of a compound
of water-glass and zinc-oxide with an addition of silicic magnesia. Writing boards
obtained by the former process, that is to say by enamelling sheet metal plates, are
unsuitable owing to the brittleness of the enamel surface and owing to the fact
that the surface becomes smooth by use. Similarly with writing boards, obtained
by coating paste-board plates with a layer of the before-mentioned compound, an
uneven and extremely rough surface of insufficient resistance is produced while,
moreover, the layer will adhere imperfectly to the sheet metal and will readily
crack.
The present invention succeeds in obtaining a sheet metal plate with a uniform,
strongly adhesive and resistible coating, having a very even and slightly roughened
surface and thus suitable for use in schools, and for writing purposes in general, by
proceeding in the following manner which is given as an example:
To one litre of water-glass, preferably natrium water-glass of 33 degrees Beaumé,
is added an emulsion of silicic acid obtained by stirring about 4 grammes of finely
pulverized silica, in of a litre of water and allowing the same to settle for a short
time and subsequently pouring the emulsion from the sediment. After well stirring,
the mixture is diluted with about of a litre of rain-water, then about 180 grammes
of finely powdered carbonate of lime is added and well mixed therewith and finally
the whole is mixed with 600 grammes of zinc-white and ground in a colour mill
iuto a uniform, fine pulp of creamy appearance.
Into this mass the sheet metal plates previously carefully cleaned are dipped, and
subsequently dried, which drying process requires about 12 to 15 hours at a
temperature of from 15 to 20 degrees Réaumur. After the drying process the
plates are once more dipped, dried again and are then ready for framing.
The coating or layer produced in this manner, exhibits an agreeable, faintly
blue tint. It has great adhesive capacity rendering a special priming superfluous,
and, moreover, has a dimmed or frosted surface which takes the writing well; the
same is, moreover, so resistible that writing plates manufactured in this manner may
be roughly handled without injury to the coating and without causing the coating
to peel off.
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. White writing boards or tablets consisting of sheet metal coated with a slating
compound composed of water-glass, finely divided silicic acid, powdered carbonate
of lime and zinc-white, substantially as described.
2. The process for producing white writing boards or tablets which consists in
mixing water-glass with an emulsion of finely divided silicic acid, adding first

page_text: powdered carbonate of lime, and then zinc-white, grinding the mixture into a fine
pulp, and applying the same to the sheet metal, substantially as described.
Dated this 2nd day of May 1896.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.