IMPROVEMENTS IN THE COATING AND PRESERVATION OF METALS AND METALLIC SURFACES, WHICH IMPROVEMENTS ARE ALSO APPLICABLE TO THE TREATMENT OF OTHER SURFACES."
Year: 1881

page_text: LETTERS PATENT to Thomas Stammers Webb, of 4, Palatinate, New Kent
Road, in the County of Surrey, Civil Engineer, for an Invention of
"IMPROVEMENTS IN THE COATING AND PRESERVATION OF METALS AND
METALLIC SURFACES, WHICH IMPROVEMENTS ARE ALSO APPLICABLE TO THE
TREATMENT OF OTHER SURFACES."
PROVISIONAL SPECIFICATION left by the said Thomas Staminers Webb at
the Office of the Commissioners of Patents on the 26th September 1881.
THOMAS STAMMERS WEBB, of 4, Palatinate, New Kent Road, in the County of
Surrey, Civil Engineer. "IMPROVEMENTS IN THE COATING AND PRESERVATION OF
METALS AND METALLIC SURFACES, WHICH IMPROVEMENTS ARE ALSO APPLICABLE
TO THE TREATMENT OF OTHER SURFACES."
This Invention relates more particularly to the coating and preservation of
articles or objects of cast iron or wrought iron, but is also applicable to the coating
and preservation of other metals and metallic objects as well as to many non-
metallic surfaces and bodies, as terra-cotta goods, bricks, clay mouldings, &c.
The said Invention consists in the preparation, and more especially in the mode
of application of preservative materials either in solution or held in suspension in
a fine state of division in any suitable liquid. The object being so to prepare
and apply the preservative materials as to effectually force them into the pores on
the surface of the article under treatment.
To illustrate this Invention I will take the case wherein I employ glasses, glazing
bodies, or other vitreous matters as the preservative materials.
I first prepare a glass or glazing body according to one or other of the following
formulae

page_text: (2.) White lead
or
Red oxide of lead
Borax
-
Calcined flint
and
Boracic acid
(3.) Borate of lead
Red oxide of lead
Calcined flint
(4.) Red oxide of lend
Boracic acid
Calcined flint
175 parts.
1600
10
10
"
"
"
25 "
150 parts.
150
15
"
"
85 parts.
11
»
4
5
1
If a coloured coating is required to be given to the article under treatment I
substitute for part of the lead oxide a sufficient quantity of such other metallic I
oxide as may be necessary to obtain the effect required, particulars of which will
be found fully set forth and explained in the various technical works treating of
the manufacture and colouring of glasses and glazing bodies.
The materials employed must all be finely ground, then intimately mixed and
melted to fusion in a suitable crucible. The fused mass is poured out and ground 2
up fine with any suitable oil or essence or with water to the consistence of thin
cream,
The preservative materials thus prepared are ready for use.
The metallic articles or objects to be treated are to be freed from any dirt or
scale by "pickling," or by heating, or by mechanical means, or by by all these
methods combined, & may be finally dressed by wire brushes worked by hand or
machinery.
I
The preservative materials may be applied with a brush to the articles under
treatment, but I find by experience that this does not completely effect the desired
purpose; I therefore suspend the articles under treatment in soine suitable vessel,
such as a cylinder or tank, and I completely cover them with preservative materials,
ground as above described with oil, essence, or water to the consistence of thin
cream, the preservative materials forming a bath in which the articles under
treatment are completely immersed. The vessel employed is so fitted and
constructed as to allow of pressure being readily applied to its contents. This may
be effected by many well known mechanical arrangements. If a cylinder is used:
the required pressure may be obtained by loading a piston working within the
cylinder and closely fitting thereto. Atmospheric pressure may be applied to the
contents of the vessel employed by any suitable pump, and liquid pressure may be
applied by pumping into the closed vessel with a force pump such further quantity
of the preservative materials held in suspension or solution as may be necessary to
obtain the pressure required.
The pressure to be applied varies in intensity and time according to the nature
of the articles under treatment.
A sufficient interval of time having elapsed the pressure is removed and the
articles under treatment are taken out of the bath of preservative materials, any
adhering superfluity of which may be removed by dressing with a painter's brush.
The articles are next dried and heated in a retort, muffle, or oven to a temperature
varying from a dull red to a bright orange heat, according to fusibility of the
glass or glazing body employed and the character of the articles under treatment.
When the preservative materials appear to be uniformly melted the article is
withdrawn and carefully cooled.
The vitreous surfaces obtained by any of these means may be wholly or partially
covered with a coating of gold, silver, or platina, or with successive coatings of any
two or more of those metals, preferably by applying with a brush to the vitreous
surfaces properly prepared solutions of those metals and subsequently heating to
incipient redness. These preparations of gold, silver, and platina are readily obtained

page_text: from those manufacturing chemists who prepare similar solutions for application to
pottery.
A more or less brilliant metallic lustre may be obtained on the surface of the
articles trented, whether they are metallic or non-metallic, by varying the process
as follows:
I take the glass, glaze, or vitreous body prepared by fusion and subsequent
grinding to the consistence of thin cream as above described, and I intimately mix
therewith a varying quantity (according to the effect required) of platinum chloride,
or platinum black, or spongy platinum. I then proceed to apply this mixture to
the articles under treatinent in the manner before described.
In some cases and to meet special requirements, as when the articles treated are
to be exposed to the action of corrosive gases or liquids, I take the glass, glaze, or
vitreous body prepared by fusion & subsequent grinding to the consistence of
thin cream, and I mix therewith various metallic oxides or refractory materials or
insoluble bodies, employing those best calculated from their colour or their chemical
composition to meet the requirements of the particular case, and I apply the mixture
to the articles under treatment in the manner before described.
I do not confine myself to the exact proportions of the materials here given.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Thomas Stammers Webb in' the Great Seal Patent Office on the
25th March 1882.
THOMAS STAMMERS WEBB, of 4, Palatinate, New Kent Road, in the County of
Surrey, Civil Engineer. "IMPROVEMENTS IN THE COATING AND PRESERVATION OF
METALS AND METALLIC SURFACES, WHICH IMPROVEMENTS ARE ALSO APPLICABLE
TO THE TREATMENT OF OTHER SURFACES."
This Invention relates to the coating or covering metallic surfaces and other
surfaces not destroyed by exposure to a red heat with preservative materials in the
form of glasses, glazing bodies, or vitreous substances, so prepared and applied as
to force them as effectually as possible into the pores on the surface of the article
under treatment, and give a uniform inoxidizable coating or covering thereto.
To assist in carrying out this Invention I employ certain glasses or vitreous
substances, the character of which may be gathered from the following formule,
exhibiting the quantities in parts by weight of the materials from which they may
be made

page_text: varying degrees of hardness. The product of No. I. I call “hard;" of Nos. II. and
III., "intermediate;" of No. IV., "soft."
I find that the only essential constituents of these glasses are the lead oxide, the
boracic acid, and the silicic acid. Now the flint glass specified in formula III.
contained lead oxide, 43%; silicic neid, 45%; alkalies, 12%. The calcined flint
in Nos. 1., II, and IV. was nearly pure silica, containing 98% of silicic acid.
With these data the per-centage of lead oxide, boracic acid, and silicic acid in the
total amount of the materials in each of the above formule will be found to be as
follows:-
When describing, as I shall now proceed to do, the manner in which I carry out 1
this Invention, I shall specify the formule I prefer to employ for the preparation
of these glasses or vitreous substances.
To carry out this Invention I proceed as follows-
I first prepare a glass or vitreous substance, and for that purpose I take 2 atomic
equivalents, i.e., 60 parts by weight, of silicic acid, and 4 atomic equivalents, i.c.,
140 parts by weight, of boracic acid, and with these I mix protoxide of lead varying
in quantity from 7 atomic equivalents, i.e., 780%, parts by weight to 15 atomic
equivalents, i.e., 1672, parts by weight, according as I may require a "hard," an
intermediate," or a "soft" glass, the softness of the glass increasing with the
quantity of protoxide of lead employed. The chemical equivalents here used are
protoxide of lead, 111-5; boracic acid, 35; silicic acid, 30.
"
To make the above perfectly clear I append the following formula:-"Hard”
lase 7 PhO & RO

page_text: specified any suitable metallic oxide, full description and particulars of which may
be found in the various technological works treating of the coloring of glasses.
I must however particularize one of these compounds on account of the excellent
black or blue-black coating it gives to iron. It is best prepared by adding 2 atomic
equivalents, i.e., 75 parts by weight, of protoxide of cobalt to the ingredients I
havo given above for an "intermediate" glass, i.e., (9 Pb O, 4 BO,, 2 Si O₂). This
compound, which I designate "intermediate cobalt" glass, has the formula
(9 Pb O, 2 Co O, 4 BO,, 2 Si O,), ¿.e.,—
The oxide of lead used for these glasses is that known as litharge; equivalent
proportions of minium or of lead carbonate may be substituted; white quartz sand
in the form of silicic acid preferred.
The materials employed are all to be reduced to fine powder, intimately mixed
and melted to complete fusion in a suitable crucible, by preference one made of
platina. The fused mass is poured out on a clean slab, broken up, reduced to
powder, and ground exceedingly fine with water or paraffine oil to the consistence
of thin cream. The preservative materials thus prepared are ready for use.
The articles about to be treated require to be freed from dirt. I employ the
following process to remove oxide or scale from the surface of iron and steel. I
immerse the articles in a bath of weak muriatic acid (spirits of salt). When the
scale appears to be loosened I withdraw them and remove the scale with water
and a wire brush. I now place them for 2 or 3 minutes in a bath made alkaline
with caustic lime or an alkali, and finally wash them with warm water.
To the articles under treatment, freed from dirt, I now proceed to apply the
preservative materials prepared as above described. This may be done with an
ordinary painter's brush, but I find by experience this method is not always
altogether efficacious. I prefer to suspend the articles under treatment in some
suitable vessel as a cylinder or tank, and I completely cover them with the pre-
servative materials. The glass or vitreous substance being held suspended in a
fine state of division in the water or paraffine oil, form a bath of preservative
materials in which the article under treatment is completely immersed. The
cylinder, tank, or other vessel employed is so constructed and fitted as to allow of
pressure being readily applied to its contents. If a cylinder is employed the
required pressure can be obtained by loading a piston working within the cylinder
and closely fitting thereto. Atmospheric pressure may be applied to the contents
of the vessel employed by securely closing the vessel with a properly fitted and
perforated cover and fitting thereto any suitable pump." These aro simple
mechanical contrivances in daily use and need no further explanation. The extent
of pressure applied varies with the nature of the articlo under treatment, as also
does the length of time of its continuance. These points must be determined by
the judgment of the operator. When the articles are taken out of the bath any
superfluity of the preservative materials adhering thereto may be removed by
dressing with a painter's brush. The articles are dried and placed in an oven or
muffle (similar to that used in the decoration of porcelain), which is heated to a
temperature varying from a dull red, or about 700° cent. to a bright orange, or
about 1200° cent., according to the fusibility of the glass or vitreous substance
employed. When the coating or covering appears to be uniformly melted over the
surface of the article under treatment, it is withdrawn and carefully cooled.
The vitreous surfaces thus obtained may be wholly or partially covered with a
coating of gold, silver, or platina, or with successivo coatings of two or more of
those metals, preferably by applying with a brush properly propared solutions of those
metals, and subsequently heating to incipient redness. These preparations of gold,

page_text: silver, and platina may be obtained from those manufacturing chemists who
prepare similar ores for application to porcelain and pottery.
The glasses obtained by fusing together lead oxide, boracic acid, and silicic acid
in the proportions mentioned may, when finely ground with water and paraffine
oil, as above described, be used as vehicles for applying various coloring matters
and other substances to the surfaces herein before described. A great number of
such substances might be enumerated. It is sufficient to mention the oxides of iron,
chrome, and uranium as coloring matters, and calcined flint and the sulphates of
baryta and lime as opaque bodies. These are merely mechanical mixtures, and
entirely distinct from the admixture by fusion of metallic oxides, for the purpose
of coloring before referred to. The coloring matter or other substance is added as
a fine powder to the glasses ground up with water or paraffine oil, as before
described, and a thorough mechanical admixture effected. One part of the
colouring matter or opaque body to four parts of glass makes a good mixture, but
these proportions may be varied according to, the depth of colour or opacity
required. The mixed materials are to be applied to the articles under treatment in
the manner berein before described.
Having described the nature of the said Invention, and the manner in which the
same is or may be carried into effect, I declare that what I claim as the Invention
secured to me by the herein before in part recited Letters Patent is,-
The coating or covering all surfaces not destroyed by exposure to a rod heat,
with glasses containing as essential constituents protoxide of lead, boracic acid, and
silicic acid, and varying in composition,
THOMAS S. WEBB. (L.S.)