AN IMPROVED PROCESS AND APPARATUS FOR PRODUCING ORNAMENTAL SURFACES ON WOOD
Year: 1866

page_text: PROVISIONAL SPECIFICATION left by Hamilton Wood at the Office
of the Commissioners of Patents, with his Petition, on the 7th April
1866.
I, HAMILTON WOOD, of Osnaburg Street, Regent's Park, in the County of
Middlesex, Gentleman, do hereby declare the nature of the said Invention for
"AN IMPROVED PROCESS AND APPARATUS FOR PRODUCING ORNAMENTAL SURFACES
ON WOOD," to be as follows:-
This Invention consists of a method of treating pieces of wood so as to
produce ornaments or figures upon them by charring them with red-hot metal
moulds or dies, which moulds or dies have the ornament or figure desired to
be produced upon the wood cast or cut upon them.
The Invention relates, first, to a method of constructing the dies or moulds;
second, the treatment of the wood for removing the charred surface so as to
leave a perfect figure; third, the peculiar tool or brush employed for removing.
the charred surface. The last improvement relates to the mode of constructing:
the furnace for heating the dies or moulds.
By means of my improvements in making the dies a perfect imitation. in.
every respect of the minutest lines is produced without the aid of any cutting.
tool or like hand process whatever. To accomplish this I take in the first.
place a cast in wax or other substance of the figure to be imitated, and from
this cast a model, which serves to form a matrix, is made. In order to obtain
from this a proper die or mould which must contain the figure in reverse, I
proceed to finish all the projections with an extra degree of sharpness, and

page_text: also give greater depth and dimensions to those parts which are most pro-
minent in the original figures. From the matrix thus prepared a metal
casting is obtained for the mould or die; this is to be chased and cleaned by
chasing tools and friction till fit for giving the impression.
The object of deepening the figure in the mould is in order to allow for the
increased degree the wood is charred in those sunken parts, so that when the
charr is removed the wood shews the real dimensions of the original, for
without the enlargement of the mould in those places, the proper effect could
not be produced. During the charring process much gas, vapour, and smoke
is formed at the points of contact of the red-hot die with the wood; this gas
accumulates to such an extent as would burst the wood asunder in order to
escape, and this especially in articles of high relief; to avoid this a series of
holes are bored through the surface leading to the points of the figure where
the accumulation of gas will be greatest. The top of the die is also crossed
with a series of deep cuts to allow the smoke thus escaping to pass out from
beneath the followers of the press; a series of vents are also cut on the face of
the die for the same purpose. The dies may be formed with two faces carved
with figures so as to produce at one pressure two subjects at a time.
The operation is as follows:-The dies are put into a furnace and made
red-hot; thence they are transferred to a press, and the wood to be operated
upon is placed on the die and the follower brought down upon it with great
pressure till it ceases to burn; the wood is then thrown into an alkaline bath'
consisting of a solution of soap lees, soda, or potass, the strength being deter-
mined by the quality of the water and the nature of the wood acted upon;
the die is then returned to the furnace for another heating. If the design is
of such a nature either in extent of surface or of the bold projection of the
figures that one branding will not produce the work, then several heats will be
requisite. The charred parts are scraped and brushed off between each heat,
and the last application of the die ought always to be of less heat than the
first ones.
The charr is to be scraped and brushed off as much as will yield
in the alkaline bath; then it is to be left to dry, and in so doing the shrinking
of the unburned surfaces being greater than that of the burnt, which could
not be removed, by the scraper, the latter will crumble off the more readily
by such shrinkage. The wood is then removed to a bath of acidulated water,
and the process is completed by brushing until the charred párts are all
removed and the clear wood left with the various figures produced upon it.
The qualities required in the brush to perform the work well are hardness
and stiffness, yet not so great as to scratch the surface of the wood, but suffi-
ciently rigid to produce considerable mechanical action; where sufficient

page_text: stiffness is obtained the scratching quality comes with it, and materials which
do not scratch have not the required mechanical action.
I prefer to construct my brushes of a kind of bass or broom or a vegetable
substance or weed known as keyare, which is a peculiar hard and tough
substance that will resist the effects of the alkali and acid baths, and produce
the desired effect; this material may either be used tied up in .bunches or
made into brushes.
In moulding works of great extent I make numerous moulds of the various
parts, and form the wood in sections, glueing them up afterwards to their
proper joints. In heating the moulds, care must be taken that they are not
blistered in the furnace, which must be so constructed or arranged as to
allow the heat to act on the under side of the dies, and not to sweep over the
surface as in reverberatory and common furnaces. The roof of the furnace
is constructed flat, and the flues are placed in each corner (so as to make the
heat equal in all parts) and joined in the centre on the outside, and the dies
are placed on open iron bars placed over the fuel.