IMPROVEMENTS IN THE MANUFACTURE OF POROUS OR SPONGY SUBSTANCES FROM INDIA-RUBBER, GUTTA PREGHA BALATA. OR THEIR COMPOUNDS
Year: 1868

page_text: LETTERS PATENT to Thomas Forster, of Streatham Common, and
John Heartfield, of Stanley Road, Thornton Heath, Croydon, both
in the County of Surrey, for the Invention of "IMPROVEMENTS IN THE
MANUFACTURE OF POROUS OR SPONGY SUBSTANCES FROM INDIA-RUBBER, GUTTA
PREGHA BALATA. OR THEIR COMPOUNDS."
Sealed the 26th February 1869, and dated the 2nd September 1868.
PROVISIONAL SPECIFICATION left by the said Thomas Forster and
John Heartfield at the Office of the Commissioners of Patents, with
their Petition, on the 2nd September 1868.
We, THOMAS FORSTER, of Streatham Common, and JOHN HEARTFIELD,
of Stanley Road, Thornton Heath, Croydon, both in the County of Surrey,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
THE MANUFACTURE OF POROUS OR SPONGY SUBSTANCES FROM INDIA-RUBBER, GUTTA
PERCHA, BALATA. OR THEIR COMPOUNDS," to be as follows:-
Our improvements consist in combining with india-rubber, gutta
percha, balata, or their compounds, ground animal or vegetable fibre
together with water or other liquid or substance which will generate
Гр.:

page_text: Ana Curing process, or in some cases charcoal or other absorbent
material may be used in place of fibre.
If animal fibre is used we prefer wool or hair (although silk may be
used), from half an ounce to four ounces to the pound of cleansed rubber,
or the same proportions of any of the above gums or combinations, and
sufficient color of any kind to produce the tint required in the finished
goods. The fibre may be previously ground as flock, or we grind it
together with the rubber compounds by any of the usual methods, but
by preference a pair of rollers moving at unequal speeds, and when the
fibre is perfectly broken up and combined with the rubber we add the
usual quantity of sulphur, as is well understood. We then thoroughly
wet the mass, and this we do by preferer.ce by passing it to and fro
between rollers on which water is running, but other means may be
resorted to, the object being to thoroughly saturate the fibre with water,
or it might be with other liquid or substance capable of generating
vapour in the curing process. After drying off the surface moisture we
then roll or slightly press the mass into sheets or blocks approximating to
the desired form when finished. We then proceed to prepare a mould to
retain the material while undergoing the process of vulcanization, and
this requires care. If a piece of this sponge be required 12 x 12 × 3
the mould must be of that size, but the compound should be 12 x 12 x 1,
a little more or less. The mould should consist of on iron frame 3 inches
deep by inch thick, with loose top and bottom plates perforated with
inch holes all over, and the whole of the mould being lined with coarse
cotton or flax cloth. The rubber compound must be cemented to the
lining cloth at the bottom of the mould. The mould wit!: its contents is
then rolled in a coarse cloth and clamped together with iron clamps. It
is then placed in the steam heater and covered in the usual way, care
being taken that the side upon which the compound is cemented is down-
wards. After curing it is left in the mould until cold, then removed
and the exterior skin cut away, and a perfect piece of sponge will be the
result, which may be cut into pieces of any desired form. When the
material is required of a greater length and width, and of a thickness
suitable for covering floors, we roli the composition on to a cloth of the
desired length, and of rather greater width than the finished material is
to be, and place along the sides a fillet of vulcanized rubber double at
least the thickness of the composition. The whole is then rolled on to a
cylinder or laid on to or between metal plates as is usual with other

page_text: goods, the fillets of rubber allowing the material to rise so much and no
In making such sheets we prefer to use charcoal with a small
portion of asphalte. If cotton, flax, hemp, or any such fibre is used
we treat them as we do wool or air. We should observe that from
coverings for floors we do not remove the outer skin.
Any of the above materials, as also charcoal from bones or wood, or
cork dust, will produce a spongy substance if a sufficient supply of water
is used. Alcohol or other hydrocarbons may be used, but we have found
the best results hitherto have been produced from wool or hair and water
for thick sponge, and charcoal or wood dust and water for floor coverings.
The combinations of the above fibrous or woody materials with rubber
are not new, but what is new is, combining them with water or other
liquid or vapour-producing substance, and curing them while these
or gas-producing substances are in the composition. In all
previous combinations of this kind the utmost caution of. the manu-
facturer has been used to dry all the materials as well as the rubber to
prevent sponginess in the finished goods.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Forster and John Heartfield in the Great
Seal Patent Office on the 2nd March 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we THOMAS
FOSTER, of Streatham Common, and JOHN HEARTFIELD, of Stanley
Road, Thornton Heath, Croydon, both in the County of Surrey, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Second day of September, in the year
of our Lord One thousand eight hundred and sixty-eight, in the thirty-
second year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto us, the said Thomas Forster and John Heartfield, Her
special licence that we, the said Thomas Forster and John Heartfield,
our executors, administrators, and assigns, or such others as we, the
said Thomas Forster and John Heartfield, our executors, administrators,
and assigns, should at any time agree with, and no others, from time
to time and at all times thereafter during the term therein expressed,
should aud lawfully might make, use, exercise,. and vend, within the

page_text: .
United Kingdom of Great Britain and Ireland, the Channel Islands,
and Isle of Man, an Invention for "IMPROVEMENTS IN THE MANUFACTURE OF
POROUS OR SPONGY SUBSTANCES FROM INDIA-RUBBER, GUTTA PERCHA, BALATA, OR
THEIR COMPOUNDS," upon the condition (amongst others) that we, the said
Thomas Forster and John Heartfield, our executors or administrators,
by an instrument in writing under our or their hands and seals, or under
the hand and seal of one of us or them, should particularly describe and
ascertain the nature of the said Invention, and in what manner the same
was to be performed, and cause the same to be filed in the Great Seal
Patent Office within six calendar months next and immediately after the
date of the said Letters Patent.
NOW KNOW YE, that we, the said Thomas Forster and John Heart-
field, do hereby declare the nature of the said Invention, and in what
manner the same is to be performed, to be particularly described and
ascertained in and by the following statement thereof, that is to say :—
Our improvement consists in combining with india-rubber, gutta
percha, balata, or their compounds, ground animal or vegetable fibre,
together with water or other liquid or substance which will generate
vapour in the curing process, or in some cases charcoal or other
absorbent material may be used in place of fibre.
If animal fibre is used we prefer wool or hair (although silk may be
used) from ounce to 4 ounces to the 1 lb. of cleansed rubber, or the
same proportions of any of the above gums or combinations, and
sufficient color of any kind to produce the tint required in the finished
goods. The fibre may be previously ground as flock, or we grind it
together with the rubber compounds by any of the usual methods, but
by preference a pair of rollers moving at unequal speeds, and when the
fibre is perfectly broken up and combined with the rubber we add the
usual quantity of sulphur as is well understood. We then thoroughly
wet the mass, and this we do by preference by passing it to and fro
between rollers on which water is running, but other means may be
resorted to, the object being to thoroughly saturate the fibre with water
or it might be with other liquid or substance capable of generating
vapour in the during process. After drying off the surface moisture we
then roll or slightly press the mass into sheets or blocks approximating
to the desired form when finished. Strips or pieces of the mass so
formed are subsequently placed in moulds and vulcanized as herein-after
described.

page_text: In carrying out our Invention we prefer to proceed as follows:-We
take of india-rubber cleansed and masticated 20 lbs., gutta percha 2+ lbs.,
vermillion or other suitable coloring material 2 lbs., wool or woollen
rags 1 lbs., and first mix the india-rubber, gutta-percha, and color
together in the usual manner with a pair of rollers, then add the wool
or rags and again mix until the wool is perfectly combined with the
rubber; we then add 2 lbs. of sulphur and again mix and pass the
whole mass several times through a pair of rollers over which a small
stream of water is running until the wool or fibre is well charged with
water, then after drying off the surface moisture we roll the compound
through a pair of dry rollers into a sheet of about one iuch in thickness
and cut up this sheot into pieces of the size required. The moulds we
generally use are 16 inches by 12 inches and 3 inches in depth, and the
sheet of rubber is cut into pieces a little less than 16 inches by 12. The
strip or piece of compound is fastened by means of india-rubber cement
to a metal plate inch thick, which fits loosely into the mould and is
perforated all over with holes inch in diameter and about half an inch
apart, and dust over the rest of the rubber and the mould with French
chalk to prevent adhesion. The compound is placed with the perforated
plate downwards in the moulds and the top plate is fixed on by clamps.
The mould is then placed in the steam heater and cured in the usual way,
care being taken that the side upon which the compound is cemented
is downwards. After curing it is left in the mould until cold, it is then
removed and stripped off the perforated metal plate, and the outer coat or
skin is subsequently cut away; a perfect piece of sponge is thus obtained,
In some cases the
which may be cut into pieces of any desired form.
in cooling will collapse or contract from the form of the mould by
reason of a partial vacuum being formed in the cells of the sponge. In
this case before cutting away the outer skin we pierce the sponge in
places with a fine point to allow it to regain its original form so that the
outer skin may readily be cut off by a reciprocating knife, such as com-
monly used for cutting india-rubber, the pieces of sponge being by
preference stuck on to the moveable bed of the machine, by which they
are carried along beneath the reciprocating knife as is well understood in
cutting india-rubber. The object of cementing the compound to a thin
metal plate placed at the bottom of the mould in which the substance is
cured as above described is to allow the air to escape from underneath
it and prevent cavities being formed in the under side. of the sponge. In
the first instance we used to line the mould with canvass to obtain this
sponge
2.

page_text: object, but we find that it is better attained by perforating the moulds
themselves and using a light inner perforated plate of iron or other metal
as above described. The mould in which the compound is vulcanised
may be of any shape desired,, and. is made with perforations at the top to
allow of the escape of air from the mould, so that as the compound rises
beyond the vulcanizing process it may completely fill the mould. The
mould we ordinarily employ is formed of a rectangular iron frame three
inches deep, and as before stated by about 16 ins.. by 12 ins., covered over
with top and. bottom plates which are separate from it, the top plate
being drilled all over with in. holes about 1 in. apart. The iron frame
is placed above the iron plate, and the thin perforated iron plate with a
s:rip of compound cemented on to it is placed into the frame and rests
on the bottom plate. The mould is then covered over with the top plate,
which fits within the sides of the mould and is supported by a flanged
rim fixed around it, which rests on the top of the sides. The top and
bottom plates are then clamped together and the mould is placed within
a steam heater with the compound within it to be cured as above de-
scribed. If we require a sponge with very coarse pores we use wood
dust, i.c., sawdust, preferring that of the soft woods, such as lime, pear,
or deal; if the latter is used we. boil it in caustic soda and water to
remove any resin, then well wash it and soak it in acid and water as
described in a Patent, No. 1222, granted to me the said Thomas Forster
on the Thirteenth day of April 1868. Lime or pear does not require the
soda preparation, only soaking in the acid solution and the thoroughly
dried by gentle heat; the acid must then be neutralized and, the woody
fibre well washed and drained and dried or combined in its inoist state
with the rubber. The object of treating the wood with acid is that it
may be carbonized by the heat during vulcanization and so be readily
reduced into powder and washed out of the sponge.
We also find that a good black sponge may be made by combining
20 lbs. of rubber and 10 lbs. of asphalt, 2 lbs. gutta percha, 2+ lbs.
sulphur, 1 lbs. cotton or linen fibre, and treating them as before de..
scribed. The proportion of asphalt may be very much varied, we think
the above quantity the best, but have had good results with equal
weight of rubber and asphalt as well as from the following combina-
tion: 20 of rubber, 2 asphalt, 20 lbs. of vegetable charcoal, and 2. of
sulphur combined and treated with wet rollers as before described..
In the manufacture of covering for floors or for similar purposes we

page_text: prefer to use wood or cork dust or charcoal in the proportion of 15 or
20 parts to 22 parts of rubber or its compounds and 2 of asphalt, with
2 of sulphur, mixing them and treating the mass with water as before
described, then rolling it out into sheets of about the thickness desired
for the finished article. It may either be fastened by india-rubber
cement to a perforated sheet of metal, as zinc, or be rolled on to a cloth
of a greater width. A fillet of vulcanized rubber of about inch wide
and the thickness desired for the finished sheet is fastened to the edge of
the sheet by india-rubber cement, this allows the sheet room to assume
its desired size; it is then to be rolled on cylinders and cured in the
usual manner, which is well understood. We should observe that (in
the case of floor coverings) we do not remove the outer skin, but this
skin may form the upper and under surface of the floorcloth, and may
be painted or ornamented in any suitable manner.
It will be obvious to any intelligent workman that the proportions
may be varied in many ways. There will however be little or no
difference in the article produced, whether it be made with wool, flock,
hair, silk, or ground sponge, flax, cotton, linen, or other vegetable fibre
so long as care has been taken to saturate them with water.
Sawdust will make sponge with larger cells, being itself in larger
particles.
Instead of using water in the process above described alcohol or other
hydrocarbons or other fluids or substances which will generate vapour
may be used in place thereof; we prefer however to employ water as
above described.
In witness whereof, we, the said Thomas Forster and John
Heartfield, have hereunto set our hands and scals, this First day
of March, One thousand eight hundred and sixty-nine.