Improvements in Cloth Covered Plaster Blocks for Ceilings, Walls, Partitions, and the like.
Year: 1889

page_text: Date of Application, 14th Sept., 1889-Accepted, 19th Oct., 1889
COMPLETE SPECIFICATION.
Improvements in Cloth Covered Plaster Blocks for Ceilings, Walls,
Partitions, and the like.
I, ALFRED JOHN PARIS of 1510 Pine Street, St. Louis, State of Missouri, United
States of America, Fire-proofer, 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 fire-proof plaster-cloth moulded in sections, in which the
plaster is completely inclosed within burlap or other fibrous material except such
portion as oozes through said burlap, and thus helps to protect the cloth which incloses
the plaster; and the invention consists in features of novelty hereinafter fully described
and pointed out in the claims.
Fig. 1 is a detail perspective under view of the ceiling, and face view of the walls
of a room, with its studs and joists to which my plaster-cloth blocks have been
secured.
Fig. 2 is a detail vertical section taken on line 11-11, fig. 3 and shows one of the
studs of the wall with an edge view of my plaster-cloth blocks secured to it, and a
section of the finishing coat applied, with the clinch between the blocks.
Fig. 3 is a detail horizontal section taken on line, 111-111, fig. 2, and shows a
stud of the wall with an edge view of my plaster-cloth blocks secured to said joists
and a section of the finishing coat applied, the stud being surmounted by the usual
stringer that supports the joists. Fig. IV is a vertical section of the mould in which
the block is formed, and shows the burlap laid within the same and the intermediate
layer of plaster laid thereon. Figure V is a vertical section of the mould, with the
cloth plaster-block inclosed therein, and shows the burlap folded around the plaster and
the compressor placed thereon. Figure VI is a top view of a section of the burlap as
it is placed in position on the mould, the said mould beneath being shown in broken
lines. Fig. VII is a like view with the upper flap of the burlap folded over the
plaster. Figure VIII is a top view of one of the blocks with the margins of burlap
that extend along the open side and end beyond the mould turned inward and folded
over the block, so that the plaster may be firmly held on all sides by the folded burlap.
Fig. IX is a detail transverse section taken on line 1X-IX, Fig. VIII, and shows
the marginal side edge of burlap folded inward on the block and the main lap of the
burlap folded over it, the double lap being brought into level outline by the pressure
of the follower in the mould, as shown in Fig. V: and Fig. X is a like view of the
end of the block, taken on line X-X, Fig. VIII, the marginal end fold being
turned inward over the main fold previous to its pressure into uniform outline by the
follower in the mould. Fig. XI is a top view of one of the blocks in the process of
formation, the burlap (instead of being in the previously-described rectangular form)
being cut in an irregular angular shape approximating the form of a letter-envelope
blank, the end overlaps alone folded. Fig. XII is a like view, the overlaps being all
folded. Fig. XIII is a vertical detail section of a joint corner of the ceiling-wall,
showing my device when I break joints at said corner turns by bending alternate
plaster-blocks around said corner.
Referring to the drawings, 1, represents the mould in which the plaster-blocks are
formed, and 2 is the follower that compresses and equalizes the upper outline of the
block, and which may be operated by any suitable screw or lever press frame.
3, represents the burlap or other suitable fibrous or other material in which the
plaster of the block is inclosed, which material, as shown in Figs. IV and VI, is first
laid in and around the mould, having a bottom layer 4, a marginal extension 5, on
one side of the mould, like extensions 6, at its ends, and a sufficiently wide extension 7,
of said material on the remaining side to fold over and cover the layer of plaster 8,
that is placed on the burlap or other fibrous material within the mould.

page_text: I prefer to construct the plaster in accordance with the following formula, although
the proportions may be slightly varied, according to the position that the plaster is to
occupy. About thirty-two per cent. quicklime, about thirty-two per cent. plaster of
Paris, about sixteen per cent. sand, about sixteen per cent. pulverized coke, and about
four per cent. glue, to which is to be added, or may be added, a suitable amount of
hair to bind the plaster, in conjunction with the glue, with the usual amount of water
to bring the material into plastic condition.
While the bounden quality of the plaster may be improved by the addition of
the hair, yet, as the plaster blocks are completely inclosed and held within the
folded burlap, a serviceable block may be constructed for some purposes without the
use of hair.
9 represents the partition-studs, onto which and onto the stringer 10 the plaster-
cloth blocks 11, that cover the walls, are secured by nails 12. 13, are the joists that
rest on said stringers, and to which the ceiling blocks (also marked 11, as the counter-
parts of those attached to the wall) are secured by nails 12.
14 represents the finishing-coat of plaster that is spread on the blocks, and 15 are
the clinches between the plaster-blocks, which re-enforce the hold of the plaster to the
blocks.
The operation of construction of the sections or blocks of plaster-cloth is as follows:
A piece of burlap or other suitable material is cut of adequate size, as shown in
Fig. VI, for folding around and forming a tight inclosure of the plaster to prevent it.
cracking and disintegrating. The said section of burlap being cut, it is laid in and
over the mould, 1, in the position shown in figure IV, so as to have a sufficient sup-
plemental width on one side the mould to lap over the plaster-block when it is
counterlapped and sufficient supplemental margins on the other side and ends of the
mould for folding back, so as to safely inclose and hold in the plaster. The section of
burlap having been placed in position, as stated, and shown in Fig. IV, a suitable
amount of the plaster, which has been prepared according to the formula already
described, is laid on the burlap in said mould, as is also shown in the same figure.
The narrow marginal edge 5 may then be lapped or folded over on the plaster, as
shown in Figs. V and IX. The wide supplemental portion 7 of the burlap is then
folded over said plaster, as shown in said figures, entirely covering or nearly so, the
plaster, and the narrow marginal side fold that has, as stated, been previously folded,
as shown in Figs. V and IX.
While I have shown and described the narrow side magin 5, as first folded over and
the wide lap after, and that is my preferred course of procedure, yet I do not
confine myself to that rotation, for the wide lap may, if desired, be first turned
over and the narrow one after. In either case, after the two side counterlaps have
been folded, then the two narrow end laps are folded over inward, as shown in
Fig. X. and said projecting maginal end edges, which when first folded over, as
shown in said figure, break the regularity of outline on the top of the block, are
forced down into the plastic plaster of the block by the pressure of the follower or
compressor 2.
16 represents the end folds, and 17 the side folds, of the burlap when the burlap-
blank is cut, as shown in figures XI and XII, approximating the shape of the blank
of a letter-envelope.
For some kinds of plastering I prefer to cut the burlap-blank and fold it in the
latter described form, as it produces no multiple edge folds at the edges, only pro-
ducing a double lap where the margins of the side folds overlap the edges of the end
folds. This arrangement produces a manifold alone at the juncture of the corners of
the folds in the centre of the block, which is easily pressed in the mould by the com-
pressor to effect a uniform outline on top, and which manifold, it will be seen, comes
immediately in contact with the joist or stud, as the case may be, and one of the
attachment nails, passing through the centre of the block, in consequence passes
through said manifold ply and securely holds the same.
In Fig. XIII is shown my device for breaking joints at the junction corners between
the ceiling and wall, in which alternate blocks are made to form united ceiling and

page_text: wall blocks to prevent the very common cracking of the plaster at said corner
junctions of the ceiling and wall plaster. To easily effect the bending of the block
I score or cut the burlap across the middle of said block, as shown at 19, which
definitely lays out the corner line and removes the main obstruction to effecting the
bend viz., the adverse brace of said burlap. It will be seen that the round turn of
the burlap, as it encompasses the plaster provides a catch-hold for the finishing cont
of plaster that is applied after the attachment of the blocks even when said blocks
are nailed immediately in juxtaposition to each other; but I prefer to attach them,
as shown in Fig. II, with a slight intervening space, 18, between them, which provides
an opportunity for the mortar of said finishing coat to be forced through and form the
clinch 15. It will be seen that where the junction-line follows under and in line with
a joint, still, even then, the round edges of the block provide a light curvilinear clinch
that is of decided advantage in securing the adhesion of the finishing coat.
As the plaster is entirely encased within the burlap the folds of which turn around
its edges, it is held and firmly bound against disintegration; also, being so bound, a
much thinner layer of plaster is effectual to do the work required than is necessary
without said binding. The blocks are, in consequence, thin, light, and easily handled,
and, when required, bent around curves or corners; also, in driving the nails for the
attachment of the blocks the plaster is securely held by the inclosing burlap from
disintegration. If the burlap did not constitute the outer layers and bind around the
edges of the block, there would be effected no encompassing binding influence that
could effectually hold the plaster from disintegration during the concussion from
the driving of the nails.
I do not confine myself to burlap for the envelope of the plaster, for, while it is
my preferred material, any other suitable fibre, as stated, may be advantageously
used.
In the construction of the sections or blocks of the plaster-cloth, the said blocks
are generally moulded about thirty-two inches long, which is of sufficient length to
reach across two spaces between joists or studs, as the case may be, to which they are
secured by nails at the ends and middle, without the intervention of lath, the use of
which combustible material is thereby entirely avoided. My preferred width for said
blocks is about sixteen inches but 1 do not confine myself to the above-mentioned
length and width, which may vary according to the uses for which it is required and
the convenience of the plasterer.
It is preferred to leave the blocks in the mould in which they are pressed for
about five minutes, when they are sufficiently set, so that they can be removed there-
from and the moulds vacated for future use. Now, it will be seen, that, not only by
the entire enveloping of the plaster-blocks with the burlap are said blocks firmly held
and bound against disintegration in the process of attachment, and afterward from
the settling of buildings and other causes; but, also, another very important feature
in their application is that the plastering of a building by this system can be com
pleted at once. The workmen do not require to wait for the shrinkage and setting
of one coat before the application of another. The finishing coat can be applied
immediately after the attachment of the blocks. In practice it is generally preferred
to first stop the intervening clinch-spaces between the blocks, and then immediately
apply the finishing coat, so that it may engage in integral affinity with the plaster of
the intervening stops and clinches. Again, as the plaster of the sections is set before
their attachment to the studs and joists, and they are preferably attached in position
to break joints, there can be no extended cracks in said plaster. It will also be seen
that, unlike with common plastering, where each of the primary layers of the three-
fold coat has to settle, dry, and set, before the application of the succeeding coat, and
the whole has to season before the house is habitable, by the use of these previously-
prepared plaster-blocks, on which alone is applied the thin-finishing-coat, houses can
be inhabited almost immediately after completion.
The great danger from the use of lath when, in times of conflagration, the heat
springs the lath, which then throws the plaster and presents a highly combustible
media for the spread of the fire, is, by the use of these enveloped plaster-blocks,

page_text: entirely avoided. Means for the avoidance of the use of lath where timber is scarce
is also an additional advantage in such sections.
For
Another adaptation or use to which this fire-proof cloth is put, is that of the back-
ground and sliding screens for theatrical scenic representations on the stage.
adaptation to that purpose the plaster cloth may either be made in thin sheets of any
breadth and length required, or may be secured in sections to a suitable movable
frame, and, in either case, after erection, it should receive its finishing surface coat,
which presents a smooth glossy surface for the representations to be painted thereon.
It will be seen that by the use of these fire-proof scenic slides on the stage a very
fruitful cause of conflagrations in theatres would be avoided.
In conclusion I would state that the reason that hair was not stated in the formula
as one of the ingredients that are used in the construction of the plaster (and it was
there only stated that it might be beneficially added in certain cases) was that, as the
fabric completely envelopes the plaster and firmly holds it from disintegration, it
exercises the functions of the hair and makes its use unnecessary in most cases; but
when the plaster cloth is constructed for use in the last-named purpose (for sliding-
screens for scenic representations) and other like uses, a suitable amount of hair in
the composition of the plaster is preferred, so as to re-enforce and enable it to with-
stand the vibrations consequent on the sliding of the screens.
Having now particularly described and ascertained the nature of my said invention
I declare that what I claim is
1. In fire-proof plaster-blocks for ceilings and walls &c., the combination of the
plaster layer 8, and the enveloping burlap or other fibre layersland folds that entirely
inclose it, substantially as described and for the purpose set forth.
2. In fire-proof plaster-blocks for ceilings and walls, &c., the combination of a
layer of plaster constructed in accordance with the formula specified and the envelope
of burlap or other fibre on which said layer of plaster rests and extensions of which
fold over both sides and ends of said plaster layer and are arranged to hold it from
disintegration, substantially as described, and for the purpose set forth.
3. In fire-proof plaster-blocks for ceilings, walls &c., the combination of the
enveloping layers of burlap or other fibre and the intervening layer of plaster,
composed of quick-lime, plaster-of-Paris, sand, pulverized coke and glue, as herein
specified, the burlap being folded entirely around the plaster and its meshes filled
therewith, substantially as described, and for the purpose set forth.
4. In fire-proof plaster-blocks for ceilings, walls &c., the combination of the plaster
layer 8, constructed in accordance with the formula herein specified, the burlap or
other fibrous cover that entirely envelopes said layer and holds it from disintegration,
the burlap on one side across the middle of said block being scored and the block
bent along said line until each half is at a right angle to the other, substantially as
described, and for the purpose set forth.
5. In fire-proof plaster-blocks for ceilings, walls &c., the burlap envelope-blank cut
in approximate form to that of the letter-envelope, the central oblong portion of
which blank fits within the mould in which the blank is pressed, the plaster layer 8
composed of quick-lime, plaster of Paris, sand, pulverized coke and glue, as herein
specified, the angle flaps 16, and 17 of said burlap or other fibre cloth being folded
over said plaster-envelope to entirely inclose the same and hold it from disintegration,
substantially as described, and for the purpose set forth.
Dated this 17th day of August 1889.
H. W. FITZPATRICK,
70, Wellington Street, Glasgow, Agent.