Bradford reporter. [volume] (Towanda, Pa.) 1844-1884, 1860-08-16
The Plaster Blackboard.

Inquiries are so frequently made from dir
ferent parts of the State, as to the constTuc-
ton of the Plaster Blackboard, used in the
State Normal School, that it may be well to
give, through the journal, q particular de-
scription of the mode of preparing it:
In the first place, the scratch coat made
with coarse sand. is spread upon the laths az
usual, and the broom goot follows being left i
little rough under the float" When the
brown coat is perfectly dry, the black coat is
laid on. This is prepared OF mason's putty"
and ground plaster and beach sand, mixed in
the usal proportions for hard finish The CO.
loring matter is lampblack, wet with alcohol
or wh>key, forming a mixture Of the consist
ency of paste This is mixed with the other
ingredients just as they are about to be spread
upon the wall. The quantity Of coloriug to
be used must be sufficient to make black
surface the suiliciency being determined by
experiment, no rule be given,
For IC square yards Of black finish, take
! II pecks Of Masons Putty l II pecks of
Beach Sand l l pecks of Ground Plaster
l u pounds Of Lampblack wet up with Il
gallons Of Whiskey.
An Intelligent mason can very soon try eX-
perimcn.s so as to insure success. 1t is to be
remembered that the black surface requires
more working with the smoothing trowel, than
ordinary white finish. 1t should be finished
by being softly smoothed with a wet brush
When perfectly dry, it is nearly as hard as
slate, and almost as durable, if carefully used
Great care should be taken not to put in too
much Iampback.
The advantages of this kind of black sur,
face over the ordinary blackboard are, |. The
chalk easily takes effect upon it. ,. The
chalk is much more easily wiped off. 3. There
is but little noise made in writing upon it. t.
There is no reflection Of light upon it. 5 1t
is cheaper it costs but trile more than ordi-
nary hard GniSh
In building new school house it would be
well to have belt Of this black surface pass
entirely around tae room, at the proper height
In . common school, when small children are
to use It, its lower edge should be about two
feet from the floor, extending thence upward
from to l2 teet. At the lower edge there
should be chalk trough" extending the
whole length, made by mailing a thin strip of
board to the plank which bounds the black
board, leaving a trough two inches in width
and depth, in which to place the chalk, brush
es, pointers, &c; this would also catch the
dust which is wiped from the board The up
per edge should be bounded by a simple
moulding
lite BRUSHES The best thing for removing
the chalk from the board is brush made Of
the size of a shoe brush, with a wooden han
die on the back side the face being covered
with a sheep skin with the wool on. This re-
moves the chalk at a single sweep, without
wearing the surface, and without dirting the
hand Of the operator. This is great i'm
provement over a dhStcloth or a sponge In
all cases let the board be kept dry never al
low pupil to aet the wiper when removing
the chalk
Bcnorat;o2-By long use, especially if the
surface IS ever cleaned with a wet wiper, this
kind Of black board becomes too smooth and
glossy upon the surface the chalk passes over
it without taking effect, and the light is re-
aected by it, A very simple wash applied
with a whitewSh brush, will Immediately re-
store It this wash is made by dissolying one
part of glue to two parts of alum, so as to
make a very thin solution. It is well to have
this wash slightly coloTed with lampblack.-
Care sho1ld be taken that this wash do not
have too n,GCh body.
The above directions, if carefully observed,
it is heleyed, will be found sufficient to enailo
any district to procure, at a cheap rate; an
ADEQUATE amount of blackboard, ready for use
at all times. If these suggestions shall tend
to promote The welfare of the schools, by inn
proving the means of instruction in the dis
tricts, the writer will hove a sufficient reward.