AN IMPROVED PROCESS OF HARDENING WOOD
Year: 1876

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for the Invention of "AN IMPROVED
PROCESS OF HARDENING WOOD." A communication from abroad by Louis
Bertin, alias Bertin-Badoureau, of Paris, France.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark at
the Office of the Commissioners of Patents on the 28th January 1876.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent.
"AN IMPROVED PROCESS OF HARDENING WOOD."
This Invention relates to an improved process of treating wood of various kinds
in order to render the same hard, compact, and more or less homogeneous, whereby
it may be used as a substitute for box wood for engravers' purposes, or for large
printing characters, weavers' shuttles, or for other purposes to which hard woods
are generally applied. The wood is first cut transversely to the grain into short
lengths of about 2 to 6 inches, more or less, and is then boiled in water or steamed
until the whole of the matter contained in the pores as yet unconverted into
ligneous fibres becomes softened. During this treatment I add from time to time
a little potash or soda to the water to facilitate the expulsion of any gummy or
resinous matter that may be in the wood. The wood is removed while still hot,
and subjected to considerable pressure, say 5 tons, more or less, the wood being
placed with the grain horizontally to expel the soft matter from the pores. In this
condition the wood presents a somewhat spongy appearance, as may be readily
ascertained by squeezing a portion in the hand after removing it from the press,
which shows that the pores are open and that by the pressure the walls of the pores
have been brought into intimate contact. The wood is then subjected to a further
treatment, which consists in immersing and boiling it in glue or other suitable
adhesive material. The glue should be of superior quality both as regards strength
and transparency. The wood should be plunged in the glue immediately it leaves
the press, otherwise it will dry and may become liable to split; the glue should be
of such strength as to form wben cold a jelly of rather less consistency than that
formed by glue for ordinary uses.
The glue will be absorbed by the wood by capillary attraction alone, or pressure
may be applied to facilitate the absorption, if preferred, but in practice it has been
found unnecessary.
The wood in this condition and while still lot is then returned

page_text: to the press, the grain being placed in a horizontal position in order that tho
pressure may be exerted on the walls of the pores, whereby the superfluous glue
will be expelled and the walls of the pores will be brought into intimate contact
and cemented together, so as to form a solid mass of ligneous fibres of great
density.
The wood is allowed to dry under pressure, after which the external surface
which is more or less stained with the water and glue may be removed, and the
wood is then ready for use. The wood may be dyed of any color desired during
the boiling, from the color of ebony to that of box wood. If a light colored wood,
such as white pine, be employed, an excellent imitation of box wood is produced
suitable for engravers' use.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Melville Clark in the Great Seal Patent Office on the 15th
July 1876.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. "AN IMPROVED PROCESS OF HARDENING WOOD." A
communication to me from abroad by Louis Bertin, alias Bertin-Badoureau, of
Paris, France.
The object of this Invention is to form a close, hard, compact, and also
homogeneous material, by taking almost any of the native or foreign woods, and
by a process herein-after mentioned make it hard and close grained so as to adapt
it to the purposes required in many of the arts, as, for instance, a substitute for box
wood for engraving on, or for making the larger kinds of type letters to print from,
or for making shuttles to weave with, or any other use for which hard, close, and
tough grained wood would be desirable.
As box wood is every year growing more scarce, and is even now difficult to
obtain in large quantities or sizes, this article (compressed wood) would make a
substitute for box wood at a much reduced price, and at the same time fill a want
much felt in the art of wood engraving.
All wood is composed of tissues of woody fibre. Tissues of wood consist of
collections of cellular pores of general uniform character, permanently combined
together by the more or less complete union of their outer surfaces.
In these
cellular pores circulate, in the plant life, the sap that goes to make the fibre of the
wood.
:
The nature of this Invention consists in taking advantage of the above
constitution of the cellular pores of wood by preparing it in the following
manner I first cut the wood in small lengths transversely across the fibre of the
wood, from 2 to 6 inches (more or less) in length, and then boil the wood in water
or steam it until all the matter contained in the pores of the wood not yet formed
into woody fibre is softened. In boiling or steaming I sometimes add a small
quantity of potash or soda to the water, to assist in removing any pitchy or
resinous matter that may be in the wood; I then remove the wood while yet warm
to a press of considerable power, say 5 tons (more or less), laying the grain of the
wood in a horizontal position, and put it under sufficient pressure to express the
soft matter from the cellular pores of the wood. In this state the wood has a
somewhat spongy appearance, which will be readily seen by pressing a piece in the
hand after its removal from the press, showing that the pores of the wood are open,
and that by pressure are made to close or yield, and the sides of the open pores to
come together. The wood is now ready for the next stage of the process, which is
that of immersing and boiling the wood in glue (or its equivalent). The gluc
should be of the best quality of strong light colored glue. The sooner the wood is
put in the glueing process after leaving the press or first stage of the process the
better, as in drying, the wood is apt to crack if too long a time intervenes between

page_text: the first process of boiling in water and the second process of boiling in glue.
There should be enough glue in water to make when cold a jellified mass thinner
than for ordinary work. The glue will be taken up by capillary attraction, or if
preferred, may be forced in by pressure, but by experience I have found that
capillary attraction answers every purpose. The wood is now while hot removed
to the press, laid with the grain or fibre of the wood in a horizontal position so as
to press the sides of the fibre or pores of the wood, and by pressure to expel all
surplus glue, and to press the sides of the cellular fibre so as to make them come
together and be glued, making a solid mass of great density. In this state the
wood is allowed to dry under pressure; when dry the outside surface, which will be
found more or less stained by boiling and glueing, is removed. The wood is now
ready to be put into shape for any purpose or use that hard, tough, and compact
wood may be applied to.
It will be seen by the foregoing description of the process of making "compressed
wood" that it does not consist in filling the pores with any material, but on the
contrary in freeing them of all materials and glueing their sides together by closing
the pores under pressure, so as to form a solid mass of fibre.
We have only to consider the strength of wood when two or more pieces are
glued together in a proper manner with good glue, to realise the immense strength
and density of wood, when every individual pore of the wood is glued together
under pressure in one solid mass.
If desired the wood can be tinted in the boiling process, almost any desired color,
from black to represent ebony, to canary yellow color to represent box wood.
When some of the light colored woods are used, such as white pine, the result is an
admirable substitute for box wood for engraving purposes.
Having described the nature of the said Invention, and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
herein-before in part recited Letters Patent is, the process herein before described of
treating wood for various uses by first boiling or steaming the wood to loosen the
contents of the pores, then emptying the pores by pressure applied to the sides of
the wood, and finally introducing through the pores a sufficient quantity of glue to
coat their sides, and then applying sufficient pressure to collapse the pores and
place their sides in contact, so as to solidify the mass of fibre until the whole is
dry.
In witness whereof, I, the said Alexander Melville Clark, have hereunto set my
hand and scal, this Fifteenth day of July, in the year of our Lord One
thousand
A. M. CLARK. (L.S.)