An Improved Powder suitable for use in Coating the Interior of Steel and other Moulds.
Year: 1890

page_text: Date of Application, 17th Oct., 1890
Complete Specification Left, 16th July, 1891-Accepted, 12th Sept., 1891
PROVISIONAL SPECIFICATION.
An Improved Powder suitable for use in Coating the Interior of
Steel and other Moulds.
I, DANIEL STEPHENS, trading as Stephens & Co., of Dinas Silica Works, in
the County of Carmarthen, Dinas Brick and Cement Manufacturer, do hereby
declare the nature of this invention to be as follows:-
The powder which forms the subject of the present invention consists of silica
prepared in a special way and brought into a very finely divided condition.
I employ a special sort of silicious rock known as "Dinas" silica stone and found
at Kidwelly, South Wales, which contains about 98 per cent. of silica, one per cent.
of alumina, half a per cent. of oxide of iron and half a per cent. of lime. I first
wash this material carefully to remove impurities and afterwards calcine it in a
brick or other kiln; the calcined stone is then ground in an edge runner mill and is
afterwards ground in a pulverising mill whereby it is reduced into an exceedingly
fine powder resembling wheat flour in appearance. In some cases I add alumina
in the form of aluminous clay to the Dinas stone.
This powder mixed with water forms a very suitable paint for the interior of
steel and other moulds; it may also be employed for cleaning metals and for other
purposes.
Dated this 17th day of October 1890
CARPMAEL & Co.,
Agents.
COMPLETE SPECIFICATION.
An Improved Powder suitable for use in Coating the Interior of
Steel and other Moulds.
I, DANIEL STEPHENS, trading as Stephens & Co., of Dinas Silica Works,
Kidwelly, in the County of Carmarthen, Dinas Brick and Cement Manufacturer,
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:
According to this invention I use a powder which consists of silica prepared in a
special way and brought into a very finely divided condition.
I employ a special sort of silicious rock known as "Dinas" silica stone and found
at Kidwelly, South Wales, which contains about 98 per cent. of silica, one per cent.
of alumina, half a per cent. of oxide of iron and half a per cent. of lime. I first
wash this material carefully to remove impurities and afterwards calcine it in a
brick or other kiln, or if the stone be carefully selected and cleaned so as to exclude
all extraneous matter the calcining may be omitted; the stone is then ground in an
edge runner mill and is afterwards ground in a pulverising mill whereby it is reduced
into an exceedingly fine powder resembling wheat flour in appearance. The mill I
prefer to employ is that known as the Alsing mill which consists of a revolving
drum of porcelain partially filled with flint pebbles. It is desirable that the powder
should be ground out of contact with any metal as otherwise its quality may be
injured. In some cases I add a small quantity say half a per cent. of alumina in
the form of aluminous clay to the Dinas stone. This increases the cohesion of the
powder but does not otherwise improve the result.
This powder mixed with water or sour beer when obtainable forms a very suitable
paint for the interior of steel and other moulds, it should be mixed to the thickness

page_text: of whiting, as used for ceilings, that is, such as when the hand is dipped into it, it
Icaves a thin cream on the hand. For heavy castings it is made a little thicker.
The thickness to which it is put on depends on the weight and thickness of the
casting, say of an inch for very heavy castings, and 16, or less, for ordinary castings.
It should be gone over from one to three times. The mould should be sleeked as
little as possible before the paint is applied, thereby giving the paint a better chance
to enter and strengthen the mould. The paint should be sleeked well after the
superfluous moisture has soaked in. Moulds for light castings do not require
sleeking, this being a great advantage in moulding small cog wheels etc. as sleeking
the cogs of the mould always tends to disturb them. After the mould is dry, or
nearly so, and while hot they should be painted roughly over with tar, and put back
into the stove to burn off. The tar toughens the surface of the paint, which will
then stand any rush of steel. But when the powder has been mixed with sour beer
the tar may be dispensed with.
The paint is put on with a lump of flax hanging in the hand. For green mould
steel castings, the paint is dusted on the mould out of a coarse bag.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what [
claim is :-
1. The improved powder substantially as described.
2. In producing steel and other castings coating the inside of the mould with this
improved powder consisting of nearly pure silica which has been reduced to a flour
like consistency substantially as described.
3. In producing steel and other castings coating the inside of the mould with
this improved powder produced by crushing rock containing a high percentage of
silica and purified by washing and by selection or calcining and then grinding it in
a pulverising mill substantially as described.
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