Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION
~ethod for forminy artificially and rapidly patina on
copper, produc-ts thereof and solutions therefor.
BACKGROUND OF Tl-IE INVENTION
Field of the invention
This invention relates to a method for artificially and
rapidly forming patina on copper substrates, to products
therefrom, in particular to such copper subs-trates as
roofing and outside covering, and to new solutions for
rapidly forming patina on copper solution.
Description of related art
Attempts have been made in order to obtain coloring of
copper similar to patina on copper.
For instance in US patent no. 1,951,304, dated March 13,
1~34, as invented by FREEMAN et al., is disclosed a method
producing on the surface of copper and alloys thereof, an
adherent green coloration patina by treating the copper or
copper alloy with a solution of ammonium sulphate and
therea~ter exposing to oxygen. In some cases a color is
developed which is darker green than that which de~elops by
natural weathering.
In US patent no. 2,587,216, dated February 26, 1952, as
invented by QUADRIO, is disclosed a method involving the
following steps: dipping an objec-t in a bath containing a
solution oE potassium sulfide, then a second bath o~
sulphuric acid, drying, then dipping in a third bath
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containing salt ammoniac, and -then coating with shellac and
a protective coating.
In US patent no. 3,152,927, dated October 13, 1964, as
inven-ted by MATTSON et al., is disclosed an agent for the
arti.ficial green patination oE object comprising an aqueous
sludge obtained by admixing an aqueous solution containing
copper nitrate, iron sulphate and sodium hydroxide.
In US patent no. 3,434,890, dated March 25, 1969, as
invented by ARONBERG, is disclosed a process for forming
patina involving wetting a copper base alloy with a solution
volatile water soluble organic solvent such as alcohol and
salts of inorganic acids and primary amines.
In US patent no. 3,473,970, dated October 21, 1969, as
invented by ROBEY, is disclosed a composition ~or imparting
patina comprising copper sulphate, ammonium sulphate lithium
chloride, sodium dicromate, hydrochloric acid, magnesium
montmorillonite and water.
In US patent no. 3,497,~01, dated February 24, 1970, as
invented by HANSON et al~, is disclosed a me-thod for
producing synthetic patina by immersion in an aqueous acidic
solution with potassium chlorate and copper sulphate.
In US patent no. 3,725,138, dated April 3, 1973, as invented
by JONES, is disclosed a patina produced on a copper surface
by applying an aqueous acidic solution of ammonium sulphate,
sulphamic acid and iron sulphate, drying the solution to
form a film on the copper surface. The film is then reacted
with the copper surface in a humid atmosphere at a
tempera-ture oE a-t least 30C for a period of -time to form an
adhered corrosion product of which a major portion is
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insolubilized. The soluble par-ts are then dissolved, thereby
developing in the reaction produc-t the color of natural
pa-tina.
In US patent no. 4,416,940, dated November 22, 1983, as
invented by LOYE et al., is disclosed a two step process
comprising first applying an opaque pigmented base coat
containing a patina color producing colorant to a primed or
unprimed substrate, curing the base coat, applying to the
cure base coat a non-opaque top coat containing one or rnore
copper color producing additives.
SUMMARY OF THE INVENTION
Broadly stated, the invention is directed to a rapid
me-thod for artificially forming patina on copper
comprising:
a) removing any impurity present on the surface of a copper
substrate,
b) coating said copper substrate with an aqueous solution
containing sodium ions, cupper ions, acetate ions, chlorine
ions, sulphate ions, H~ ions and an OH- ions;
c) washing the copper substrate coated as in step (b) with
water and drying;
d) gently brushing the copper substrate having been dried
according to step (c), washing and drying;
e) coating said copper substrate after having been dried
according to step (d), with a aqueous solution containing
copper carbonate, ammonium chloride, copper acetate, arsenic
trioxide, copper nitrate and hydrochloric acid.
The invention is also direc-ted -to new products obtained by
-the method as deEined above and to produc-ts for forming
patina on copper.
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DESCRIPTION OF A PREFERRED EMBODIMENT
The first step of the method involves cleaning of the
surface i.n order to remove any impurity present on the
surface of the copper substrate such as varnish, grease,
copper oxide, e-tc. This cleaning is easily conduc-ted by
brushing. In a preferred embodimen-t, cold brushing is
conducted with nylon brushes having abrasive particles
embedded in cured binders such as cured phenolformaldehyde
resins, polyurethane resins and epoxy resins, These brushes
may for instance be mechanically mounted on a driven roller
bearing in mind tha-t the copper metal must touch sideways in
order to obtain good patina Eixation and polishing could
also be conducted if desired. Scoth Brite R brown pads may
be used.
After removing any impurity present on the surface of the
copper substrate, it should be borne in mind that the
substra-te must be manipulated with dirt free and grease
free intermediates and never with hands; one may use
metallic instruments or cotton gloves for instance.
After removal of -the impurities, it is important to polish
as quickly as possible the copper substrate with an aqueous
solution containing sodium ions, copper ions~ acetate ions,
chloride ions, sulphate ions, hydrogen ions and hydroxy
ions. This aqueous solu-tion is preferably obtained by mixing
from 100 to 150 ml of concentrated acetic acid, 500 to 600
grams of copper sulphate, 80 to 120 grams of sodium
chloride, 11 -to 13 grams oE hydroxide and 11 to 15 grams of
copper acetate in 4 liters of distilled water. More
preferably, the solu-tion contains 4 liters of distilled
water, 135 ml of concentra-ted acetic acid, 563 grams of
copper sulphate, 100 grarns of sodium chloride, 12 grams of
sodium hydroxide and 12 grams of copper aceta-te. The
solution is applied in large quantity whether by jet, hand,
mechanically or manually brushed until a brownish color is
obtained. Thereafter, any excess of reactant is removed with
thorough water washing. Drying is then conducted under air
pressure over all coated surfaces and -then the copper
substrate is cured for at least 12 hours, preferably in a
room having a light used for growing plants such as Gro-Lux
R Sylvania, simulating the solar light. Preferably, the
sides of the room are reflecting light with surfaces such as
mirror polished aluminum and the like. The room temperature
is about 20 à 35C and preferably 25C with a relative
humidity oE between 35 to 80% and preferably 50%.
After the drying step, the copper substrate is thoroughly
washed and lightly brushed, whether manually or
mechanically, in order to remove brownish color which is not
sufficiently adhering to the substrate. The substrate is
then pressure air dried. Thereafter, the copper substrate is
submitted to a filtered aqueous solution containing copper
carbonate, ammonium chloride, copper acetate, arsenic
trioxide, copper nitrate and hydrochloric acid until the
desired patinated copper substrate is obtained. This last
step may be repeated if desired. This solution may be
applied with a brush or a gun as desired.
Preferably, this lost solution is obtained by mixing in 6
liters of distilled water, from 300 to 360 ml of
concentrated hydrochloric acid, 100 to 160 grams of copper
carbonate, 350 to 420 grams of ammonium chloride, 375 to 450
grams of copper acetate, 20 to 75 grams of arsenic trioxide,
and 10 to 25 grams of copper nitrate. More preferably, the
solution is prepared by mixing in 6 liters of distilled
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water, 330 ml of concentrated hydrochloric acid, 130 grams
of copper carbonate, 400 grams of ammonium chloride, 400
grams of copper acetate, 65 grams of arsenic trioxide and 15
grams of copper nitrateO Then, the solu-tion is left standing
to reach equilibrium and filteredO As a prac-tical method, a
standing period of one day to ensure equilibrium is
generally considered safe before filtration.
Thereafter, the copper substrate may be allowed to dry in
the room as defined abGve for a period of 2 to 4 hours.
It is important to never handle the copper substrate with
the hands during this process.
It should be noted that these drying stages may, if desired,
be referred to as curing. ~;
The day af-ter, the patinate copper substrate is obtaine. It
may be placed in a wharehouse protected with a paper in
between.
Al-though the present invention has been explained
hereinabove by way of preferred embodiments thereof, it
should be pointed out that any modifications to these
preferred embodiments, within the scope of the appended
claims, is not deemed to change or alter the nature and
scope of the invention.
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