AN IMPROVED PROCESS FOR DIMINISHING THE INFLAMMABILITY OF WOOD
Year: 1876

page_text: LETTERS PATENT to George Ross McKenzie, of Glasgow, in the County of
Lanark, North Britain, Cabinet Maker, for the Invention of "AN IMPROVED
PROCESS FOR DIMINISHING THE INFLAMMABILITY OF WOOD."
Sealed the 5th June 1877, and dated the 9th December 1870.
PROVISIONAL SPECIFICATION left by the said George Ross MoKenzie at the
Office of the Commissioners of Patents on the 9th December 1876.
GEORGE ROSS MCKENZIE, of Glasgow, in the County of Lanark, North Britain,
Cabinet Makor. "AN IMPROVED PROCESS FOR DIMINISHING THE INFLAMMABILITY
OF WOOD."
This Invention has for its object to diminish the inflammability of wood, so as, as
much as possible, to prevent the spreading of fires in any buildings or structures in
which wood forms a part, the improved process being applicable to wood in the
shape of furniture or other portable form, as well as when used in forming buildings
or structures.
The improved process tends to strengthen and preserve the wood, and renders
it less liable to change color, and it does not interfere with varnishing, polishing,
painting, or other usual treatment of the wood.
The Invention consists in treating wood with soda crystals (monocarbonate of
soda) in an improved manner; and in carrying it out the wood is by preference
treated when in the sawn or cut condition in the form of boards or joists, for
example, rather than in that of thicker balks or masses. In the case of any variety.
of pine wood the wood is placed in a tank or open boiler in a solution containing
from 2 to 3 pounds of soda crystals per gallon of water, and being in quantity about
3 quarts for every cubic foot of wood. The wood is kept in the solution from 4 to
9 hours, during which the solution is kept gently boiling. In the case of any other
wood harder and closer grained than pine it is advantageous to first prepare the
wood by subjecting it during 1 to 3 hours to the action of steam in a closed vessel,
or instead of such steaming the boiling in the soda solution may be continued pro-
portionally longer. The boiling should also be continued longer when the wood is
of extra thickness.
An important part of the process consists in drying the wood after treatment
with the solution, not with the aid of heat, but by means of cool air, the treated

page_text: wood being piled so that the air has access to all parts of it, whilst the best result
is obtained when artificial or forced currents of air are made to pass over and through
the pile of wood.
By the present Invention, also, ground soda crystals are mixed with sawdust, and
filled in between ceilings and floors, so as whilst serving as "deafening" to also act
as a non-inflammable or difficultly-inflammable barrier to the spread of fire. In a
similar way the mixture of ground soda crystals and sawdust may be advanta-
geously filled into the internal spaces of wall partitions, lined on either side with
thin wood, and will in most cases effectually prevent the spreading of fire.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said George Ross McKenzie in the Great Seal Patent Office on the 7th June
1877.
GEORGE ROSS M. KENZIE, of Glasgow, in the County of Lanark, North Britain,
Cabinet Maker. AN IMPROVED PROCESS FOR DIMINISHING THE INFLAMMABILITY
OF WOOD."
16
My said Invention has principally for its object to diminish the inflammability
of wood; so as, as much as possible, to prevent the spreading of fires in any buildings
or structures in which wood forms a part, my improved process being applicable to
wood in the shape of furniture or other portable form, as well as when used in
forming buildings or structures.
My improved process tends to strengthen and preserve the wood, and renders it
less liable to change color, and it does not interfere with varnishing, polishing,
painting, or other usual treatment of the wood.
My Invention may in practice be applied in different degrees in different cases,
the resulting diminution of the inflammability of the wood treated being greater
the stronger the solutions are that are employed, and the longer the duration of the
treatment. A moderate application of my improved process, whilst materially
diminishing the inflammability of wood, has also the important advantage when
applied to more or less "green" or new wood of " seasoning," or in other words of
effecting a change practically equivalent to that due to the ordinary process of
seasoning, and the wood so treated can be subsequently turned in a lathe or
otherwise cut or shaped by means of tools such as are used for those purposes in
ordinary wood.
My Invention consists in treating wood with soda crystals (monocarbonate of
soda) in an improved manner, and in carrying it out the wood is by preference
treated when in the sawn or cut condition, in the form of boards or joists, for
example, rather than in that of thicker balks or masses.
And in order that my said Invention and the manner of performing the same
may be properly understood I will proceed to particularly describe what I believe
to be the best modes of applying it in certain cases by way of example.
When the object is to diminish the inflammability of the wood in what I will
term a moderate degree at comparatively small expence, and yet secure the advan-
tage of the "
seasoning "effect accompanying the treatment, I proceed as follows in
the case of American ash, bay mahogany, and yellow pine in boards about inch
thick: I boil the wood under atmospheric pressure in a tank which is by pre-
ference covered, in a solution containing about 2 pounds soda crystals for each
gallon of water.
In arranging the boards in the tank they are "pinned" or separated by small
pins or blocks, so that the liquid has free access between them, and the solution is
filled in to a depth of about six inches above the top of the wood, or so that the
wood does not become uncovered during the boiling process. The wood is held
down by clamps, screws, chains, weights, or any other convenient means, The

page_text: boiling should be continued for about 5 hours, and should then be discontinued for
about 9 hours, after which the boiling should be renewed for about 2 hours. On
the second boiling being completed the wood should be taken out of the tank as hot
as it can be handled, and be " pinned" or piled with spaces between the boards or
pieces in order to be dried, and this operation is to be effected without any extra
heat, but by currents of cool air, and may be expedited by means of artificial or
forced currents of air when conveniently applicable.
In the case of the wood being about 1 inch thick the first boiling should be con-
tinued for about 8 hours, the interval be about 18 hours, and the second boiling
about 4 hours.
When the wood is about 2 inches thick the first boiling should be for about 10
hours, the interval about 30 hours, and the second boiling for about 6 hours.
For white pine, pitch pine, oak, walnut, beech, elm, Spanish mahogany, and
similar woods the strength of the solution should be increased to 3 pounds soda
crystals for every gallon of water, but the duration of the treatment may remain
the same as herein-before prescribed for similar thicknesses of wood, it being
however sometimes advantageous to soak the wood for some hours in the cold liquid
before boiling.
When the wood is 4 inches or more in thickness it should be boiled under
pressure, and in a still stronger solution; thus, for example, a log of bay mahogany
measuring about 20 feet by 3 feet by 2 feet should be boiled under a pressure of about
80 pounds per square inch in a solution of 4 pounds soda for every gallon of water,
the first boiling being for about 20 hours, the interval about 60 hours, and the
second boiling for about 10 hours.
In the
When considerable diminution of the inflammability is desired the strength
of the solution should be of from 3 to 5 pounds soda for every gallon of water in
the cases of inch white pine or 1 inch yellow pine, and the wood should be soaked
for about 12 hours, boiled for about 10 hours, soaked again for about 24 hours, and
boiled again for about 5 hours. For similar thicknesses of oak, elm, or beech the
solution should contain from 4 to 6 pounds soda for every gallon of water.
cases of 1 inches white pine or 2 inches yellow pine the wood should be soaked
for about 20 hours, boiled for about 18 hours, soaked again for about 40 hours, and
boiled again for about 8 hours. In the cases of 3 inches by 6 inches white pine, or
5 inches by 12 inches yellow pine the wood should be soaked for about 20 hours,
boiled for about 20 hours, soaked again for a week, and boiled again for about 10
hours.
In some cases, and to still further diminish the inflammability of wood treated as
herein-before described, it may have the monocarbonate of soda applied to it in the
form of a paint or coating, being by preference combined with glue and oxide of
iron or other suitable metallic oxide.
"
In a
By my present Invention, also, ground soda crystals are mixed with sawdust, and
filled in between ceilings and floors, so as whilst serving as deafening" to also act
as a non-inflammable or difficultly-inflammable barrier to the spreading of fire.
similar way the mixture of ground soda crystals and sawdust may be advantageously
filled into the internal spaces of wall partitions lined on either side with thin wood
treated as herein-before described, and will in most cases effectually prevent the
spreading of fire.
Having thus particularly described my said Invention, and the manner of per-
forming the same, I have to state that I do not restrict myself to the precise details
herein-before described or referred to, but that what I believe to be novel and
original, and claim as the Invention secured to me by the herein-before in part
recited Letters Patent is,-
1. The treating of wood with solution of monocarbonate of soda in the improved
manner and for the purposes herein before described.
2. The drying of wood treated with solution of monocarbonate of soda by means
of currents of cold air, as and for the purposes herein-before described.
3. The applying of a mixture of sawdust and monocarbonate of soda in partitions
'

page_text: and between ceilings and floors as a barrier to the spreading of fire, as herein-before
described.
In witness whereof, I, the said George Ross McKenzie, have hereunto set my
hand and seal, this Sixth day of June, in the year of our Lord One thousand
eight hundred and seventy-seven.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
GEORGE ROSS MCKENZIE. (L.S.)