AN IMPROVED PROCESS AND Glazing ComPOSITION FOR ENAMELLING IRON
Year: 1877

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for the Invention of
'AN IMPROVED PROCESS AND Glazing ComPOSITION FOR ENAMELLING IRON."
A communication from abroad by Frederick G. Niedringhaus and William
F. Niedringhaus, both of Saint Louis, Missouri, United States of Amorica,
Manufacturers.
Sealed the 18th December 1877, and dated the 30th October 1877.
COMPLETE SPECIFICATION filed by the said William Robert Lake at the
Office of the Commissioners of Patents on the 30th October 1877.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "AN IMPROVED PROCESS AND GLAZING COM-
POSITION FOR ENAMELLING IRON." A communication from abroad. by Frederick
G. Niedringhaus and William F. Niedringhaus, both of Saint Louis, Missouri,
United States of America, Manufacturers.
- In the Specification of former Letters Patent dated 14th June A.D. 1876, No.
2453, I have described a process or method of enamelling iron ware.
The present Invention relates partly to the treatment of the enamelled ware after
baking it.
Hitherto in enamelling sheet metal ware it has been customary after the ware
has been withdrawn from the baking oven to allow it to cool freely in the open
air, but this is detrimental to the quality of the ware. To fuse the enamel upon the
iron base the ware must, as is well understood, be carried to a high degree of heat.
In cooling down from this high temperature the iron base naturally contracts more
than the newly formed enamel coating, especially when the latter is essentially a
glass, that is to say, the kind I preferably employ. Now if the cooling operation is
allowed to proceed rapidly the iron chills and shrinks before the enamel has become
properly incorporated in and attached to it, and in consequence the enamel is not
reliably adhesive, but in use splinters off.
.
To meet this difficulty I prolong the cooling of the ware as long as practicable,
and proceed as follows:-As soon as the ware (after withdrawing it from the

page_text: baking oven) can by suitable appliances be handled without injury to the enamel
and while the ware is yet in a highly heated state, it is placed where the
surrounding air is of the same temperature as the ware; it is then cooled down
very slowly, the operation taking from four to six hours.
In practice, an ordinary glass annealing furnace may be used. This retardation
of the cooling of the ware renders the enamel itself more malleable, but it is
especially valuable for the reason that it prevents any disturbance of the intimate
union that exists between the iron and the enamel when the ware is withdrawn
from the baking oven, which union is materially weakened when the ware is
allowed to cool rapidly.
The said Invention further relates to the treatment of the enamelling glaze or
paste, when for any cause it is not sufficiently acid to oxidize the metallic base.
As a rule the acid already contained in the ingredients is amply sufficient for the
perfect oxidation of the base, but occasionally from insufficient smelting of the
ingredients, or from imperfect grinding thereof, or from some of them being inferior
in quality, the enamelling glaze or paste as an oxidising agent is not energetic
enough in its action on the base. I overcome this difficulty by adding a liquid
acid to the paste after the latter has been prepared in the ordinary manner.
of the well-known liquid acids that act on iron will answer.
Any
If sulphuric acid is used, about a tea-spoonful to 100 lbs. of the paste suffices to
produce approximately the desired effect, and more can be added as required. By
these means. the glaze or paste. is, allowed to act on the metallic base with the
desired effect.
"Having thus fully described the said Invention as communicated to me by my
foreign correspondents, and the manner of performing the same, I wish it under-
stood that I claim,
First. The herein described improvement in enamelling sheet metal ware by sub-
jecting such ware after withdrawing it from the baking oven to a process of slow
cooling, as above described.
Second. The combination with ordinary glaze used in making mottled enamelled
sheet iron ware of liquid acid; as above set forth and for the purpose specified.
In witness whereof, I, the said William Robert Lake, have hereunto set my
hand and seal, this Thirtieth day of October, in the year of our Lord One
thousand eight hundred and seventy-seven.
VITEL