A NEW AND IMPROVED METHOD OF AND COMPOSITIONS FOR COATING OR ENAMELLING CAST IRON SURFACES TO PROTECT THEM FROM OXIDATION."
Year: 1879

page_text: PROVISIONAL SPECIFICATION left by Alexander Browne at the Office of
the Commissioners of Patents on the 22nd March 1879. (A communication
from abroad by Antoine François Alphonse 'Grebel, the elder, of Paris,
France, Civil Engineer.)
ALEXANDER BROWNE, of the Firm of Browne and Company, of 5, Southampton
Buildings, in the County of Middlesex, Patent Agents. A NEW AND IMPROVED
METHOD OF AND COMPOSITIONS FOR COATING OR ENAMELLING CAST IRON SURFACES
TO PROTECT THEM FROM OXIDATION." (A communication from abroad by Antoine
François Alphonse Grebel, the elder, of Paris, France, Civil Engineer.)
This Invention consists in coating or enamelling cast iron surfaces to prevent
oxidation thereof in the mould itself at the time of casting, instead of having to
make the cast iron red hot in ovens after it comes from the mould, as at present
practised for enamelling cast iron surfaces.
;-
In order to effect the above the anti-oxide coating is made as follows:-
1st. For a colourless anti-oxide coating,-
60 parts of powdered window glass.
30 parts of white sand.
2 parts of anhydrous borate of soda (borax).
The mixture to be duly fritted and ground to fine powder, to be mixed with ten
parts of finely powdered pipe clay thoroughly dried but not burnt.
2nd. For a white anti-oxide coating ten parts of the glass powder of the pre-
ceeding composition are to be replaced by ten parts of oxide of tin.
3rdly. For a blue anti oxide coating, ten parts of the glass powder of the first
mentioned composition to be replaced by two parts of oxide of cobalt.
The composition No. 2 may be treated in the same way, which gives a more firm
and beautiful appearance. Other colours may be obtained by the use of other
colorific oxides, such as have been long known, and in use for making enamels.
The proportions of oxide of tin may be varied according to the degree of opacity
or colour to be given to the anti-oxide coating. Composition of different degrees of
fusibility may be obtained suitable for the different thickness of cast iron to be
coated by increasing according to circumstances, the proportion of the fluxing
ingredients or of the silicious matter. The thicker the cast iron to be coated, so in
proportion should the fusibility be diminished. After moulding the article the
surface of the mould is to be covered with a coating of lime, which is to be smoothed

page_text: over and then coated with the vitreous composition before described, after which
the cast iron may be poured into the mould. At the heat of the molten metal the
anti-oxide composition vitrifies, affixes itself like a solder to the iron, and cools
with it.
The article thus becomes completely glazed, and it only remains to brush off the
coating of lime, which merely serves to prevent contact of the anti-oxide composi-
tion and the sand of the mould.
For moulds to be run off in the green or wet state. When the mould has been
dusted with chalk in fine powder the pattern is replaced in the mould to level the
surface of the line, or this coating may be smoothed over by other means, and it is
then a substitute for the ordinary black coating.
The powdered anti-oxide composition is then applied by means of a very fine
sieve, and afterwards the mould is carefully moistened either with wet blotting
paper, a soft swab, or with steam. For moulds and cores of dry loam or sand
this is the manner most frequently practised, and gives the most successful results.
After having dried the mould or core which has been coated with lime in the state of
slip (instead of the ordinary black coating) it is smoothed over and coated with the
anti-oxide composition (made suitably liquid with water that has boiled) to the
thickness of about of an inch; it is then thoroughly dried and run.
This improved method of enamelling is especially applicable in pipes and other
articles, the inside surfaces of which cannot be treated by the ordinary methods
and is far superior, being entirely free from any deleterious ingredients.