Improvements in the Process of and Apparatus for the Manufacture of Imitation Wood Carvings by Pressure.
Year: 1896

page_text: Date of Application, 31st Jan., 1896
Complete Specification Left, 31s! Oc!., 1895-Accepted, 23ri Jan., 1397
[Partly communicated from abroad by WESSE & Co., of Magdeburg, an1 for the
other part the invention of said THOMPSON.]
Improvements in the Process of and Apparatus for the Manufacture
of Imitation Wood Carvings by Pressure.
We, SIGMUND WILLNER, late of Hamburg, but temporarily of 31, High
Holborn, London, Merchant, and WILLIAM PHILLIPS THOMPSON, of 31, High
Holborn, London, Patent Agent, do hereby declare the nature of this invention
to be as follows:-
Numerous processes have been suggested for forming deeply impressed mouldings
from wood but the following difficulties have been fatal to most of these
processes:-
Firstly Where two different materials are used, such as veneer and wood pulp
they expand differently under pressure, and warp.
SecondlyWood under great pressure, except against the grain, is liable to
split, and wood pressed against the grain has a poor appearance and is also brittle
transversely.
Thirdly-The surface even when made of thin veneer is very apt to crack in the
mould or in the course of a few days after pressing.
Lastly-If the wood be saturated with glue in order to overcome this evil the
glue is apt to exude in warm weather or at any rate to give a sticky feel to
the goods when touched with moist hands, and further, when exposed to wet it is
liable to swell up.
Now the present invention is to overcome all these evils and to produce good
pressed wood carvings from even raw green wood which have none of these
defects.
We take almost any kind of cheap wood, beech is a very useful one, and cut it
into scantlings, preferably of about three inches square. These scantlings are now
piled loosely in a large chamber having coils of steam pipes below and also
perforated steam pipes in any convenient position. The wood being piled as
loosely as possible in the stove, steam is let in through the perforated steam pipes
for about eight hours a day for a week, then for another week the chamber is filled
with steam for six hours a day, while for the third week it is filled with steam
two hours a day. During the remaining hours of each day the steam is allowed to
escape and steam is passed through the steam pipes at the bottom, air is also
admitted in limited quantities at the bottom so as to circulate among these steam
pipes and afterwards through the wood escaping above. After the third week the
wood is kept for a few days longer exposed simply to the hot air. These
scantlings are now taken out and glued together into baulks of timber of any
desired size say three feet square, and immediately after gluing they are tightly
compressed together laterally by screw clamps, they are left thus clamped as long
as required to thoroughly harden the glue. They are now taken out and are
sawn transversely into slabs of the required thickness, say from half an inch to an
inch and a quarter according to the thickness required. These slabs are treated on
one side with a boiling solution of glue and left to stand till dry, they are then
turned over and the other side similarly treated and again dried. Veneer is now

page_text: glued to them on both sides and they are again allowed to dry. When thoroughly
dry they are either steamed with damp steam for about half a minute on the side on
which the impression is to be taken, the surplus water wiped off, and they are
placed in a cupborrd for an hour or so, or in place of this they are simply damped
with a wet sponge and placed in the cupboard. When the surface has arrived at
a certain state of dryness which the workman ascertains by feeling with his hand
and for which no other rule can be given, they are placed in the press between
moulds. These moulds can either be heated with boiling oil, gas jets, or other-
wise, or used cold, we prefer for nearly all purposes cold moulds and previous
steaming, to hot moulds and mere damping. The wood is now gradually pressed
until the full pattern is made, the pressure varying with each pattern and with
each kind of wood but easily found by experiment, simply testing one piece of
wood first until the right amount of pressure is secured. Hot moulds have the
advantage of to a certain extent converting the damp in the wood into steam and
thus altering the texture slightly to a greater depth where there is greater
pressure than where there is little. We prefer forming them hollow and passing
a continuous stream of hot oil or hot brine, high pressure steam or other hot fluid
through them. In order to prevent the glue from being sticky or hygroscopic we
prefer when steaming the wood to wipe it with a solution of chromic acid,
tannic acid, gallic acid, or other tanning material and keep it in a dark place until
the pressure is applied after which it can be exposed to daylight and the glue on the
surface thus becomes insoluble. Both surfaces can be brushed over with the tanning
material. Chromic acid or bi-chromate gives the best results but gives a somewhat
yellowish-green tint to sundry kinds of wood, while tannic acid which is next best
somewhat darkens the wood.
Dated this 21st day of I
1000
WM. P. THOMPSON & Co.,
31, High Holborn, London, W.C., Patent Agents for the Applicants.
Improvements in the Process of and Apparatus for the Manufacture
of Imitation Wood Carvings by Pressure.
We, SIGMUND WILLNER, late of Hamburg but temporarily of Cressington
Park, Liverpool, Merchant, and WILLIAM PHILLIPS THOMPSON, of 322, formerly
of 31, High Holboru, London, Patent Agent, 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:-
Numerous processes have been suggested for forming deeply impressed mouldings
or pannels from wood, but the following defects have been fatal to most of these
processes.
Firstly, where two materials are used, such as veneer and wood pulp they
expand and contract differently under heat and moisture and invariably warp.
Secondly, wood under great pressure, except against the grain, is liable to split
and word pressed against the grain has a poor appearance, and is also brittle
transversely.
Thirdly, the surface even when made of thin veneer is very apt to crack in the
n.ould or in the course of a few days after pressing.
Lastly, if the wood is saturated with glue in order to overcome this evil, the
glue is apt to exude in warm weather or at best to give a sticky feel to the hands
when touched by noist hands, and further when exposed to wet or damp is liable
to swell up.

page_text: Now the present invention is designed to overcome all these evils and to produce
good pressed wood carvings from even raw green wood which has none of these
defects.
We take almost any kind of cheap wood, beech is a very useful one, and cut it
into scantlings, preferably of about three inches square. These sc intlings are now
thoroughly dried if they are not dried previously. In our Provisional Specification
we described a process of drying which we obtained from Weisse & Co. of
Magdeburg. Since the drawing up of our Provisional however we have found that
other processes now in use in Liverpool are superior to this Weisse process and we
therefore wish to make no claim for this special method of drying, but use any
ordinary drying apparatus now in use. The wood being thoroughly dried, the
Scantlings are glued together into baulks of timber of any desired size and
immediately after gluing they are tightly compressed together laterally by screw
clamps. They are left thus clamped until the glue is thoroughly hard. They are
now taken out and are sawn transversely into slabs of the required thickness, say
from half an inch to one and a quarter inches according to the thickness required.
These slabs are treated on one side with a boiling solution of glue and left to stand
till dry. They are then turned over and the other side similarly treated and again
dried. Veneer is now glued to them on both sides and they are again allowed to
dry, or in place of this arrangement the veneer is glued to them at the one
operation. When thoroughly dry according to Messrs. Weisse & Co.'s practice,
they are steamed for about half a minute on the side on which the impression has
to be taken, the moisture wiped off and while still in the damp state compressed ;
a cold die and an ordinary press being used for this purpose. Now we propose
instead of this to use heated moulds, the moulds being formed hollow and connected
by flexible tube connections with boiling oil boiling brine or superheated steam
supply, or they can be made box shape and gas jets inserted in the box, holes
being perforated on each side to supply air.
The invention is best described by aid of the accompanying drawings, in
which,
Figure 1 is a vertical section, and
Figure 2 a sectional plan of a mould heated by a hot fluid.
Figures 3 and 4 similar views of a mould heated by gas.
In these the shaded part is the section of the iron or steel mould, B B are hollows
either cast or in this case drilled in the mould and the holes not required stopped
CC junctions, DD ventilating holes, E perforated gas pipe.
up.
If heated moulds be used, mere wetting of the surface of the wood is sufficient
and the hot mould drives the damp in the form of steam deeper into the wood than
would otherwise be the case. The wood is gradually pressed until the full pattern
is made, from three quarters of a minute to three minutes being employed in
pressing, the time and the pressure varying greatly with each kind of wood and
with each mould, moulds in high relief requiring longer pressure than moulds in
low relief and the only method of ascertaining the amount of pressure required is
by using a test sample when the workman with a little practice will at once see by
the behaviour of the wood the amount of pressure required. In order to prevent
the glue from being sticky or hygroscopic we prefer to moisten the wood or
impregnate the glue used in attaching the veneer, or still better the veneer itself,
with a solution of chromic acid, tannic acid, gallic acid or other tanning material
and to keep it in a dark place or away from inuch bright light until placed in the
press. After pressure it can be exposed to daylight and the glue on the surface
thus becomes insoluble and no longer sticky. Both surfaces can be brushed over
with the tanning material. Bichromate of potash gives very good results, but
slightly colours some kinds of wood, while tannic acid and tanuin are apt to rather
darken the wood. The communicated part of this invention is the method of
preparing the slabs of wood for damping and pressing, and is a modification
communicated by Weise & Co. of Weidemann's process as patented by A. J. Boult,
No. 4355 of 1893 and now owned by Engraved Wood Limited. The combination

page_text: of the use of heated dies with this formation of wood and moistening the surface
instead of simply steaming it, also the use of tauning materials for the purposes
described is the invention of W. P. Thompson.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is,-
1. The manufacture of pressed wood carvings by forming dry and preferably soft
wood into scantlings, preferably of about three inches square, gluing or cementing
them together, keeping them pressed together while thus glued until the glue is
hard, cross cutting them into slabs, coating them with veneer on each side and
pressing substantially as described.
2. In the formation of pressed wood carvings substantially as described in Claim 1,
moistening the surface to be impressed and impressing with heated dies, substantially
as described.
3. In the manufacture of pressed wood carvings in which veneer is attached
to wood by glue or other cementaceous material, impregnating the surface with a
material having a tanning action on the glue whereby the glue is made insoluble.
Dated this 30th day of October 1896
WM. P. THOMPSON & Co.,
Of Liverpool, Manchester, Birmingham, and London, Patent Agents.