Galvanising.
Year: 1895

page_text: Galvanising.
We, RICHARD HEATHFIELD, of No. 1 Leadenhall Buildings, in the City of
London, Metal Merchant, and WILLIAM STEPNEY RAWSON, of No. 21 Greycoat
Gardens, Victoria Street, in the County of London, Electrical Engineer, do
hereby declare the nature of this invention to be as follows:-
:-
When articles of iron or steel are galvanised by electrolytical deposit of zinc,
it often happens that portions of their surface do not receive the desired coating.
Our invention relates to means of effecting the coating of these parts so that
the article treated, instead of presenting a more or less patchy surface, shall
appear uniformly coated. For this purpose, we clear the article of iron oxide by
treating it with dilute acid, or mechanical treatment and we then dip it in a boiling
bath of chloride of tin dissolved in pyro-phosphate of soda or in other suitable
solution of tin salts. This gives a coat of tin to the part or parts that had not
received deposit of zinc, so that the whole surface appears galvanised. The
article, after being tinned as above described, may be again electrolytically coated
with zinc which will then become deposited on the tinned parts as well as the rest
of the surface.
Dated this 24th Jor of Denombor 1805
ABEL & IMRAY,
Agents for the. Applicants.
An improvement in Galvanising.
We, RICHARD HEATHFIELD, of No. 1 Leadenhall Buildings, in the City of
London, Metal Merchant, and WILLIAM STEPNEY RAWSON, of No. 21 Greycoat
Gardens, Victoria Street, in the County of London, Electrical Engineer, 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:—
When articles of iron or steel are galvanised by electrolytical deposit of zine, it
often happens that portions of their surface do not receive the desired coating.
Our invention relates to means of effecting the coating of these parts, so that
the article treated, instead, of presenting a more or less patchy surface, shall
appear uniformnly coated.
For this purpose, we clear the article of iron oxide by treating it with dilute
acid, or when there is an appreciable amount of oxide present, by mechanical
treatment, and we then dip it in a boiling bath of chloride of tiu dissolved in
pyro-phosphate of soda or in other suitable solution of tiu salt.

page_text: A suitable solution is that of chloride of tin in pyro-phosphate of soda in the
following proportions.
To parts pyro-puospnate of soda to
600 parts water.
As it is advisable that the deposit of tin should not be too rapid it is preferred
to begin with the solution cold and to gradually increase its temperature to boiling
point.
An immersion of about 30 minutes is sufficient to coat the bare iron and also
to give the zinc a coating which is of advantage in protecting the zinc against the
action of acid vapour, sea water and other corroding agents.
This gives a coat of tin to the part or parts that had not received deposit of
zinc, so that the whole surface appears galvanised.
The article, after being tinned as above described, may be again electrolytically
coated with zinc which will then become deposited on the tinned parts as well as
the rest of the surface.
When the article -is to receive a second coating of zinc after the bare spots are
covered, the time of immersion may be reduced to about 10 minutes.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
In the electrolytic galvanising of iron or steel, treating articles imperfectly
galvanised with a tinning solution applied in the manner and for the purpose set
forth.
Dated thin 1711
J
1000
ABEL & IMRAY,
Agents for the Applicants.