Improved Process for Producing Liquid Clay or Slip for Casting. in Moulds.
Year: 1892

page_text: Date of Application, 5th Sept., 1892-Accepted, 22nd Oct., 1892
COMPLETE SPECIFICATION.
Improved Process for Producing Liquid Clay or Slip for Casting.
in Moulds.
A communication to me from KARL GOETZ, D.L.L., of Karlsbad, Bohemia.
I, EDMUND EDWARDS, of the firm of Edwards and Co., Patent Agents and
Engineers, of 35, Southampton Buildings, Chancery Lane, in the County of
Middlesex, 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, that is to say :-
Whilst by the ordinary process the liquid mass of clay, or slip to be poured
into moulds for making articles of porcelain, stoneware and the like is so prepared
that the mass has to be mixed with about one and a half parts of water in order
to make it sufficiently fluid for casting, the process which forms the subject of
the present invention consists in mixing the mass with an aqueous solution of
one of the bases of soda, potash, lithia, oxide of ammonium-i.e. with a lye of soda,
potash, hydrate of lithia and hydrate of ammonium-or with an aqueous solutiou
of a carbonate or multi-carbonate of these bases-but not including the carbonates
of soda-as also of the silicates and fluor-salts of these bases, such as soda glass,
fluoride of ammonium, and thus the mass is made sufficiently fluid and fit for
casting. It is quite sufficient to add to 1000 parts by weight of the mass of clay
about three parts by weight of the said solution, selecting the proportion most
suitable to the mass. For earthenware a little additional water is necessary.
In order to prevent the grey colour which is sometimes produced upon articles
of porcelain, especially at their edges, during the process of burning, it is
advisable to add to the aqueous solution sufficient cinnabar and to dissolve it in
the same, so as to give to the entire solution a weak rose tint. By adding cinnabar
the liquefying of the mass is accelerated and the facility of casting is ensured.
The mixture or slip prepared in the manner described although the large
quantity of water present in the mixture as ordinarily used is absent, is never-
theless more fluid than the latter, contains no air bubbles, flows into the extreme
parts and into all the narrowest and smallest details of the mould, and allows the
manufacture in this way of articles which hitherto could not be formed by casting,
but had to be shaped or turned separately.
The articles made by the improved method are of much more uniform quality
and density, more solid, stronger and less liable to break than those made from
ordinary material or slip, or than those turned or finished separately. Wbile
by the ordinary process the mould can at most be used three times in succession
and then requires to be dried, the mould can by the use of the mass prepared in
the manner described above be used 10 to 12 times and can then be dried much
more quickly. For this reason the troublesome drying of the moulds is greatly
reduced and injury to the moulds themselves is also largely prevented. Conse-
quently for a new factory a smaller stock of moulds than usual is necessary in the
first place, and afterwards the consumption of this stock is also considerably reduced
as compared with the present system now in use.
Moreover the contraction which takes place during the burning of the articles
is greatly reduced. Articles manufactured by the improved process require in
the burning oven about 150 degrees less heat than hitherto. Also the mass need
not be ground for more than 16 hours and may be at once prepared with the
soda or alkali solution, whilst by the old process 22 to 24 hours grinding is
necessary and a subsequent much longer storing of the mass.
By the use of the new process ornamentation by colours to be burned in can
readily be applied to the casting.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
A process for producing liquid clay or slip, adapted and fit for casting, consisting
in mixing the mass with an aqueous solution of one of the bases of soda, potash,
lithia, oxide of ammonium-i.e. with a lye of soda, potash, hydrate of lithia,
hydrate of ammonium-or with an aqueous solution of a carbonate or multi-
carbonate of these bases-without including the carbonates of soda-as also of
the silicates and fluor-salts of these bases, with or without the addition of cinnabar,
substantially as described.
Dated this 3rd day of September 1892.
EDWARDS & Co.,
35, Southampton Buildings, London, Agents for the Applicant.