Improvements in and relating to the Coating of Metals.
Year: 1893

page_text: Date of Application, 21st Jan., 1893
Complete Specification Left, 12th Oct., 1893-Accepted, 18th Nov., 1893
PROVISIONAL SPECIFICATION.
Improvements in and relating to the Coating of Metals.
We ALEXANDER ELLIOT HASWELL and ARTHUR GEORGE HASWELL both
of IV Theresiammgasse No. 10 Vienna, in the Empire of Austria, Chemists, do
hereby declare the nature of this invention to be as follows:-
In the Specification of Letters Patent No. 1355 A.D. 1890 we have described
certain improvements in coating metals.
Our present invention relates to further improvements according to which, for
depositing a compound of binoxide of lead and binoxide of manganese by means
of an electric current on iron, steel, nickel and aluminium, and copper tin and
alloys of copper and tin, zinc and nickel, two different galvanic baths are made
use of.
The one bath, solely adaptable for iron, steel, nickel and aluminium is termed the
gunbarrel bath, whereas the other in which copper tin and alloys are coated, is
designated as electro-enamel bath. The gunbarrel bath contains in one hundred
litres of water ten to twenty-five kilogrammes of uitrate of lead, one half a
kilogramme of nitrate of manganese and two kilogrammes of nitrate of ammonia.
The specific gravity of this bath is 1.23.
The electro enamel bath consists of a solution of oxide of lead in caustic soda or
caustic potash and nitrate of soda or nitrate of potash and contains in one hundred
litres ten kilogrammes nitrate of lead and seven to eight kilogrammes caustic soda
or its equivalent in potash.
According to the present invention the process of forming the binoxides of lead
and manganese on iron, steel, nickel or aluminium in the gun-barrel bath is as
follows.
The article to be coated is first well cleaned by means of any well known method,
usual in galvano-plating processes so as to be perfectly free from oxides and fatty
matters, after which it is connected to the positive pole of the battery or dynamo
machine and inserted in the gun-barrel bath. The negative electrode consist of
sheet aluminium inserted in porous clay diaphragms filled up with pyrolusite ground
to the size of hemp seed. The pyrolusite oxidises the hydrogen generated on this
pole, thereby preventing a deposition of metallic lead from the bath. This bath
contains in one hundred litres of water, ten to twenty-five kilogrammes nitrate of
lead, one half a kilogramme nitrate of manganese and two kilogrammes nitrate of
ammonia.
The bath is replenished during the process of coating by adding a mixture of basic
carbonate of lead (white lead) and carbonate of manganese in the proportion of
one hundred parts lead to three of carbonate of manganese in the form of a very
fine powder. During the process of coating the bath is kept in continual
circulation either by means of stirring or by forcing air through it with a blower.
The electric current required is 0-3 to 0.7 ampere per square decimetre of surface
of article with a tension of 2 to 2 volts.
The enamel-bath, in which articles of copper and tin and alloys of these with
zinc and nickel are coated contains in one hundred litres of water, ten kilogrammes
nitrate of lead and seven to eight kilogramines of caustic soda or its equivalent in
A solution of ten
caustic potash and is prepared in the following manner.
kilogrammes of nitrate of lead in fifty litres of water is gradually poured into a
solution of seven to eight kilogrammes of caustic soda in fifty litres of water, both
liquids being previously heated up to 70° Celsius and kept at about this temperature,
being well stirred all the while, for about hour.

page_text: In order to replenish this bath during the process of coating, hydrate of
lead prepared in the following manner is thrown into the bath in small quantities.
Eighty grammes nitrate of lead dissolved in two hundred and fifty cubic
centimetres of water is poured into one hundred cubic centimetres of water
containing twenty grammes caustic soda after mixing well, the precipitate is allowed
to settle, the supernatant liquid drawn off and the precipitate kept under water, a
small quantity of carbonate of manganese added to this preparation causes a
combined deposit of the binoxides of lead and manganese on the articles to be
coated.
The negative pole consists either of carbon, sheet lead or steel inserted in
diaphragms filled either with a solution of bichromate of potash which oxidises
the hydrogen generated here, or with caustic soda solution of the same specific
gravity as the bath. The bath and diaphragm contents being of same specific
gravity the diffusion of bath liquid into the diaphragm cells is very slow and in
consequence the loss through deposition of metallic lead is exceedingly small.
From time to time the contents of the cells are renewed with a fresh solution of
caustic soda. In both baths the proportion of the surface of articles to that of the
cathodes is in the proportion of one to two or two and one half.
The articles to be coated are cleaned in the same manner as those treated in the
gun-barrel bath and are then connected with the positive pole of the battery or
dynamo-machine. The necessary electric current is 0.7 to 1 ampere per square
decimetre of surface of article with a tension of 2 volts. Good circulation in the
bath is kept up in the same manner as in the gun-barrel bath but the articles are
withdrawn after fifteen minutes exposure.
Dated this 21st day of January 1802
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in and relating to the Coating of Metals.
We, ALEXANDER ELLIOT HASWELL and ARTHUR GEORGE HASWELL, both
IV Theresiammgasse No. 10, Vienna, in the Empire of Austria, Chemists, 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:―
In the Specification of Letters Patent No. 1355 A.D. 1890 we have described
certain improvements in coating metals.
Our present invention relates to further improvements according to which for
depositing a compound of binoxide of lead and binoxide of manganese by means
of an electric current on iron, steel, nickel and aluminium, and copper tin and
alloys of copper and tin zinc and nickel two different galvanic batlis are made
use of.
The one bath, solely adaptable for iron, steel, nickel and aluminium is termed
the gun barrel bath whereas the other in which copper, tin and alloys are coated is
designated as electro-enamel bath. The gun barrel bath contains in one hundred
litres of water, ten to twenty-five kilogrammes of nitrate of lead, one half a
kilogramme of nitrate of manganese and two kilogrammes of nitrate of ammonia.
The specific gravity of this bath is 1.23. The electro enamel bath consists of a
solution of oxide of lead in caustic soda or caustic potash and nitrate of soda or
nitrate of potash and contains in one hundred litres ten kilogrammes of nitrate of
lead and seven to eight kilogrammes caustic soda or its equivalent in potash.
According to the present invention the process of forming the binoxides of lead
and manganese on iron, steel, nickel or aluminium in the gun barrel bath is as
follows
-
The article to be coated is first well cleaned by means of any well known method

page_text: usual in galvano-plating processes so as to be perfectly free from oxides and fatty
matters, after which it is connected to the positive pole of the battery or dynamo
machine and inserted in to the gun barrel bath. The negative electrode consist of
sheet aluminium inserted into porous clay diaphragms filled up with pyrolusite
ground to the size of hemp-seed. The pyrolusite oxidises the hydrogen generated
at this pole, thereby preventing a deposition of metallic lead from the bath. The
said bath contains in one hundred litres of water, ten to twenty-five kilogrammes
nitrate of lead, one half a kilogramme nitrate of inanganese and two kilogrammes
nitrate of ammonia.
The bath is replenished during the process of coating by adding a mixture of
basic carbonate of lead (white lead) and carbonate of manganese in the proportion
of one hundred parts lead to three of carbonate of manganese in the form of a very
fine powder. During the process of coating, the bath is kept in continual
circulation either by means of stirring or by forcing air through it with a blower.
The electric current required is 0.3 to 0.7 ampère per square decimetre of surface
of article with a tension of 2 to 2 volts.
The enamel bath in which articles of copper and tin and alloys of these with zinc
and nickel are coated contains in one hundred litres of water five to len
kilogrammes uitrate of lead and seven to twelve kilogrammes of caustic soda or its
equivalent in caustic potash and is prepared in the following manner :-A solution
of five to ten kilogrammes of nitrate of lead in fifty litres of water is gradually
poured into a solution of seven to twelve kilogrammes of caustic soda in fifty litres
of water, both liquids being previously heated up to 70° Celsius and kept at about
this temperature, being well stirred all the while, for about hour.
In order to replenish this bath during the process of coating hydrate of lead
prepared in the following manner is thrown into the bath in small quantities.
Eighty grammes nitrate of lead dissolved in two hundred and fifty cubic centi-
metres of water is poured into one hundred cubic centimetres of water containing
twenty grammes caustic soda, after mixing well, the precipitate is allowed to settle,
the supernatant liquid drawn off and the precipitate kept under water; a small
quantity of carbonate of manganese added to this preparation causes a combined
deposit of the binoxides of lead and manganese on the articles to be coated.
The negative pole consists either of carbon, sheet lead or steel inserted in
diaphragms filled either with a solution of bichromate of potash which oxidises the
hydrogen generated here, or with caustic soda solution of the same specific gravity
as the bath. The bath and diaphragm contents being of same specific gravity the
diffusion of the bath liquid into the diaphragm cells very slow and in consequence
the loss through deposition of metallic lead exceedingly small. From time to time
the contents of the cells are renewed with a fresh solution of caustic soda. In both
baths the proportion of the surface of the articles to that of the cathodes is one to
two or two and one half.
The articles to be coated are cleaned in the same manner as those treated in the
gun-barrel bath and are then connected with the positive pole of the battery or
dynamo-machine. The necessary electric current is 0.7 to 1 ampère per square
decimetre of surface of article with a tension of 2 volts. Good circulation in the
bath is kept up in the same manner as in the gun-barrel bath but the articles are
withdrawn after fifteen minutes exposure.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
clain is :-
1. The coating of articles of irou, steel, nickel and aluminium with an electro-
deposit consisting of an anti-corrosive coating of binoxide of lead and binoxide of
manganese in the above described gun-barrel bath, substantially as above
described.
2. The process for depositing binoxide of lead with traces of binoxide of
manganese ou copper, tiu and alloys substantially as above described.

page_text: 3. The use of nitrate of ammonia as an ingredient of galvano-electric baths for
depositing a coating of the above named oxides on iron, steel, nickel and
aluminium and of nitrate of soda in an alkaline solution of lead oxide for the same.
purpose of depositing the above oxides on copper, tin and alloys, substantially as
above described.
Dated this 12th day of October 1902
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicants.