Improvements in the Manufacture of Blackboards for Scholastic Use.
Year: 1892

page_text: Date of Application, 5th Feb., 1892-Accepted, 5th Mar., 1892
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Blackboards for
Scholastic Use.
I, GEORGE FREDERICK REDFERN, of the firm of G. F. Redfern & Co., The
Feneral Patent Office, No. 4, South Street, Finsbury, in the County of London,
Patent Agents, do hereby declare the nature of this invention (a communication
to me by A. C. Lemcke, of Cassel, in the Empire of Germany, Decorator,) 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 the manufacture of blackboards for scholastic use from
card-board, linoleum or other suitable material, whereby the writing surfaces are
prevented from warping or splitting as is the case with wooden blackboards and
the writing is protected from becoming rubbed or indistinct and the surface from
becoming scratched or otherwise damaged.
In the accompanying drawing,
Figure 1 is a front elevation of a blackboard made according to this invention;
and,
Figure 2 is a section on the line ax of Figure 1:
Figures 3 and 4 are respectively an elevation and a section of the board with
one of the writing surfaces removed in order to shew the frame and filling material
hereinafter described which is placed between the two writing surfaces:
Figures 5 and 6 are sections of part of the board drawn to an enlarged
scale.
Similar letters in all the figures indicate similar parts.
According to this invention a sheet a of card-board or other suitable material is
first covered on its inner surface with a suitable cement; laths or strips b, also
covered with the said cement, are then laid along the edges of the card-board or
other sheet a so as to form a frame; similar laths or strips c are then laid within
the said frame in order to strengthen the blackboard A.
The square spaces formed by these laths or strips b, c are then filled in with a
light material such as rushes or the like. The whole upper surface is then
covered with cement, the second writing surface e is laid on and the whole is
submitted to strong pressure until the cement has become hard and all the parts
firmly connected together.
The edges are protected by a frame f, the edges of which extend beyond the
surfaces of the blackboard so that when shifting or turning the blackboard any
writing thereon shall not be rubbed out or rendered indistinct or the writing surfaces
damaged.
The outer surfaces of the sheets a, e of card-board or the like are preferably
faced with a black coating in order that the writing thereon shall be clear.
Provided the blackboard be kept sufficiently long under pressure, that is to say,
until the cement shall be thoroughly set, it will always remain flat or level even
though a wet sponge be used to efface the writings. Moreover the blackboard is
not liable to split like those manufactured of wood generally do after they have
been long in use; and it is prevented from yielding under the pressure of the writer
by the interposition of the laths or strips c and 6 which form a skeleton frame.
The spaces of this frame being filled up and the whole submitted to pressure, the
blackboard will neither split nor warp.

page_text: 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 :-
1. The manufacture of blackboards for scholastic use by placing a frame of
laths or strips between sheets of suitable material which constitute the writing
surfaces, the spaces between the laths or strips being filled with suitable light
material such as rushes, the whole being firmly connected by cement and pressure,
and having the edges protected by a frame adapted to prevent the blackboard
from warping or splitting and the writing surfaces from becoming damaged or
scratched when moving the blackboard, substantially as hereinbefore described.
2. The use of blackboards made in the manner hereinbefore described with
reference to the accompanying drawing.
Dated the 5th day of February 1892.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.