Improvements relating to the Coating of Metals.
Year: 1891

page_text: Date of Application, 3rd Dec., 1891
Complete Specification Left, 19th Aug., 1892-Accepted, 24th Sept., 1892
PROVISIONAL SPECIFICATION.
Improvements relating to the Coating of Metals.
I, EDWIN NORTON of Maywood, in the County of Cook, State of Illinois
and United States of America, Manufacturer, do hereby declare the nature of
my invention to be as follows:-
This invention relates to an improved process of coating sheets of steel or iron
with tin, lead or zinc.
In the coating of black steel or iron sheets with these other metals as heretofore
practiced, one commonly employed process has been the following:-The sheets
are first prepared for taking the coating of metal by removing the scale oxidation
and foreign matter from the surface by immersing the sheets in a bath of diluted
sulphuric acid, commonly called a pickling bath. Upon removal from this bath
the acid is carefully washed off from the sheets and they are at once completely
iminersed in pure, clean water to protect them from fresh oxidation which would
ensue if they were exposed to the atmosphere. The plates are next taken from the
water and while still wet are immersed one by one in a bath of palm oil which is
maintained in a heated state at a temperature just sufficient to evaporate the water
and at the same time heat the plate and prepare it for the next step in the process.
From this oil bath the plates are taken to and immersed in a bath of molten tin
covered with a body of palm oil, the plates being passed first through this body of
oil before coming in contact with the molten tin beneath. A dozen or more sheets
are commonly immersed in this bath at a time and are then taken out and laid in
a pile. The operator next takes each sheet singly and brushes the surplus tin off
fron it with a hempen brush and then dips the sheet into another bath of molten
tin, and finally into the grease pot where, by means of a lifting device, the sheet is
passed up slowly between polishing rolls running in the heated oil and given its
final polish and finish. This constitutes what is known to the trade as the palm oil
process of tinning sheets. The several pots in this process require to be kept at
different temperatures. Thus the pot in which the sheets are first plunged into the
oil cannot be so highly heated as the pot containing the netal and oil, because if it
were heated to the temperature of the latter, the contact of the oil with the wet
sheets would cause the oil to foam and sputter and boil over. This foaming of the
oil is a great annoyance and can only be avoided where the sheets are immersed
in a large body of oil by keeping the oil at a comparatively low temperature. The
sheets are left in this pot until the moisture has been evaporated from them, 80
that when they are put into the pot containing the oil and molten tin, there will be
no longer any traces of moisture upon them which can produce steam or excite the
highly heated oil in the pot with the metal. This process also requires several
handlings of the sheets, and there is a very considerable loss of metal through
oxidation especially while it is being brushed. For these and other reasons great
skill and long practice are required in the practice of this process and the workmen
who understand it are scarce and hard to obtain. The consumption of tin plate
has also grown so rapidly in recent years that it was impossible to supply the
demand by this old process which is slow, and hence manufacturers have been in
many instances led to adopt the quicker process described in the next paragraph.
Another process of coating tin and terne plates by which it has been sought to
obviate some of the difficulties encountered in the palm oil process has come into
extensive use and is as follows:--In this process the plates are first pickled and
washed in clean water as in the other process, and then instead of inserting them
in a palm oil bath, they are immersed at once in a pot containing molten coating
metal and a flux floating and resting upon the metal composed of muriate of zinc

page_text: or "acid" and lime. This flux does not become agitated and overflow as does the
palm oil when heated to the extent necessary to keep the metal in proper fluid
condition. After passing through this flux and metal, the plates are transferred
into the grease pot and polished by rolls as in the other process. In this acid
process a very considerable economy in labor, fuel and waste from oxidation of the
tin is obtained. But the use of this new flux is attended with great injury to the
quality of the plates as the acid attacks the steel body beneath the coating and
causes pin holes to appear in the plates after manufacture, and they are much less
durable than the plates produced by the palm-oil process for the same reason.
The fumes arising from the flux are also very injurious and unpleasant to the
workmen.
In my present invention, which is in reality an improvement upon the palm oil
process, because I employ the oil as a flux instead of the acid, I aim to overcome
the difficulties heretofore encountered in the practice of such process and to obtain
the economy of labor, fuel etc. which attends the practice of the acid process. The
principal objection other than the expense of attending the oil process has been
the tendency of the oil to foam and boil over when the wet sheets are inserted in it
and this difficulty I have fully removed. In carrying out my invention I pass the
iron or steel sheet as it comes from the bath of water through one or more pairs of
heated rolls, the surface of which are continuously supplied with a covering of
heated oil or other suitable flux, so that the rolls will impart such covering of flux
to the sheets as they pass between them. The rolls should be heated to a sufficient
degree to evaporate the moisture from the surface of the plates and if necessary to
accomplish this thoroughly I employ two or more pairs of the rolls. In this
manner the moisture is evaporated simultaneously with the application of the flux
coating so that there is no time for oxidation to take place upon the surface of the
plate. At the same time, the temperature of the rolls is imparted to the plates
themselves so that they are brought to a temperature suitable to produce the best
results when they are placed in the molten metal. The sheets thus prepared having
the water evaporated and both sides covered thoroughly with the oil or flux are
ready to be immersed in the bath of oil flux and molten coating metal without
causing any agitation of the flux in the pot with the metal. The remaining treat-
ment is the same as previously practiced in the acid or single pot process.
By this improved process I obviate the objections to the oil process as heretofore
practiced an obtain the economy in labor and fuel attending the acid process
without employing and encountering the objections attending the use of acid.
Dated this 19th day of November 1891.
EDWIN NORTON.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements relating to the Coating of Metals.
I, EDWIN NORTON, residing in Maywood, in the County of Cook in the
State of Illinois, United States of America, Manufacturer, do hereby solemnly
declare the nature of my invention for Improvement in the Process of Coating
Sheets of Steel or Iron with Tin, Lead or Zine, and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement:-
This invention relates to an improved process of coating sheets of steel or iron
with tin, lead or zinc.
In the coating of black steel or iron sheets with these other metals, as heretofore
practiced, one commonly employed process has been the following: The sheets
are first prepared for taking the coating of metal by removing the scale oxydation
and foreign matter from the surface by immersing the sheets in a bath of diluted

page_text: sulphuric acid, commonly called a pickling bath. Upon removal from this bath
the acid is carefully washed off from the sheets and they are at once completely
immersed in pure, clean water to protect them from oxydation which would ensue
if they were exposed to the atmosphere. The plates are next taken from the water
and while still wet are immersed one by one in a bath of palm oil which is
maintained in a heated state at a temperature sufficient to evaporate the water and
at the same time heat the plate and prepare it for the next step in the process.
From this oil bath the plates are taken to and immersed in a bath of molten tin
covered with a body of palm oil, the piates being passed first through this body of
oil before coming in contact with the molten tin beneath. A dozen or more sheets
are commonly immersed in this bath at a time and are then taken out and laid in a
pile. The operator next takes each sheet singly and brushes the surplus tin off
from it with a hempen brush and then dips the sheet into another bath of molten
tin and finally into the grease pot where by means of a lifting device the sheet is
passed up slowly between polish rolls running in the heated oil and given its final
polish and finish. This constitutes what is known to the trade as the palm oil
process of tinning sheets. The several pots in this process require to be kept at
different temperatures. Thus the pots in which the sheets are first plunged into
the oil cannot be so highly heated as the pot containing the metal and oil, because
if it were heated to the temperature of the latter, the contact of the oil with the
wet sheets would cause the oil to foam and sputter and boil over.. This foaming of
the oil is a great annoyance and can only be avoided where the sheets are immersed
in a large body of oil by keeping the oil at a comparatively low temperature. The
sheets are left in this pot until the moisture has been evaporated from them, so
that when they are put into the pot containing the oil and molten tin, there will be
no longer any traces of moisture upon them which can produce steam or excite the
highly heated oil in the pot with the metal. This process also requires several
handlings of the sheets, and there is a very considerable loss of metal through
oxydation especially while it is being brushed. For these and other reasons skill
and long practice are required in the practice of this process and the workinen who
understand it are scarce and hard to obtain. The consumption of tin plate has
also grown so rapidly in recent years that it was impossible to supply the demand
by this old process which is slow, and hence manufacturers have been in many
instances led to adopt the quicker process described in the next paragraph.
Another process of coating tin and terne plates by which it has been sought to
obviate some of the difficulties encountered in the palm oil process has come into
extensive use and is as follows: In this process the plates are first pickled and
washed in clean water as in the other process, and then instead of inserting them in
a palm oil bath, they are immersed at once in a pot containing molten coating
metal and a flux floating and resting upon the metal composed of muriate of zinc
or "acid "and lime. This flux does not become agitated and overflow as does the
palm oil when heated to the extent necessary to keep the metal in proper fluid
condition. After passing through this flux and metal, the plates are transferred
into the grease pot and polished by rolls as in the other process. In this acid
process a very considerable economy in labor, fuel and waste from oxydation of the
tin is obtained. But the use of this new flux is attended with great injury to the
quality of the plates as the acid attacks the steel body beneath the coating, and
causes pin holes to appear in the plates after manufacture and they are much less
durable than the plates produced by the palm oil process for the same reason.
The fumes arising from this flux is also very injurious and unpleasant to the
workmen.
In the present invention, which is in reality an improvement upon the palm oil
process, because I employ the oil as a flux instead of the acid, I aim to overcome
the difficulties heretofore encountered in the practice of such process and to obtain
the economy of labor, fuel etc. which attends the practice of the acid process. The
principal objection other than the expense of attending the oil process has been the
tendency of the oil to foam and boil over when the wet sheets are inserted in it and

page_text: this difficulty I have fully removed. In carrying out my invention I pass the iron
or steel sheet as it comes from the bath of water through one or more pairs of
heated rolls, the surface of which are continuously supplied with a covering of
heated oil or other suitable flux so that the rolls will impart such covering of flux
to the sheets as they pass between them. The rolls should be heated to a sufficient
degree to evaporate the moisture from the surface of the plates and, if necessary,
to accomplish this thoroughly I employ two or more pairs of rolls. In this manner
the moisture is evaporated simultaneously with the application of the flux coating
so that there is no time for oxidation to take place upon the surface of the plate.
At the same time, the heat of the rolls is imparted to the plates themselves so that
they are brought to a temperature suitable to produce the best results when they
are placed in the molten metal. The sheets thus prepared having the water
evaporated and both sides covered thoroughly with the oil or flux are ready to be
immersed in the bath of oil flux, and molten coating metal without causing any
agitation of the flux in the pot with the metal. The remaining treatment is the
same as previously practiced in the acid or single pot process.
By this improved process I obviate the objections to the oil process, as heretofore
practiced, and obtain the economy in labor and fuel attending the acid process
without employing and encountering the objections attending the use of acid.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1st. The improvement in the old palm oil process of tinning or coating iron or
steel sheets with tin or other metal, herein described, and consisting in first taking
the wet sheets from their water bath and simultaneously drying off the moisture,
heating the sheets and fluxing or coating them with palm oil by passing the sheets
between heated metallic rolls supplied with oil, and then immersing the sheets thus
heated, dried and fluxed in a bath of molten tin or other metal, substantially as
specified.
2nd. The process of coating metal plates with molten metal which consists in
first pickling the plates, then passing the plates while still wet between hot rolls
supplied with an oil flux whereby the sheets are simultaneously dried and fluxed
then passing the sheets into the molten metal, substantially as specified.
111:
IT S
L
1000
Witnesses:
H. M. MUNDAY.
EMMA HACK.
EDWIN NORTON.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicant.