Edouard Bastarache on tue 23 apr 02
perspective)
URANIUM and CERAMICS
Here is through some excerpts of articles by authors having published =
works on ceramics (of which some became very rare) during the 19th. and =
20th. century, an outline of what was the primarily use of uranium and =
compounds in ceramic products, essentially devoted to the manufacture of =
vitrifiable colors, colouring materials for enamels, lustres and glazes. =
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Nowadays, these products are part of the history of ceramics and are not =
used anymore in the current manufacture of ceramic wares in the Western =
world. The toxicity of uranium and compounds and their radioactivity =
have placed these materials under close scrutiny with a formal ban on =
their trade and use.=20
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Excerpts on the use of uranium and compounds in ceramics :=20
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1) In the book "Trait=E9 des Arts C=E9ramiques ou des poteries", Alex. =
Brongniart, January 1854 :=20
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Uranium oxide, suitably prepared, can give a yellow-orange color of a =
great vividness which one obtains only with difficulty using potash =
antimoniate.=20
One obtains yellows by means of potash antimoniate and lead oxide. It is =
close to the " Yellow of Naples ", more or less darkened by the addition =
of varying amounts of zinc oxide, iron oxide and sometimes tin oxide. =
One can still add uranium oxide in order to obtain a darker yellow.=20
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Vitrifiable color for porcelain :=20
(Uranium oxide yellow-orange which is used for backgrounds)=20
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Components=20
Yellow-Orange n=B0 45=20
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" Rocaille " flux (75% minium, 25% silica)=20
75=20
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Pure uranium oxide=20
25=20
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The preparation of the oxide is carried out by treating pitchblende with =
acidic solutions.=20
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2) In the book "Le=E7ons de C=E9ramique", volume 1, Alphonse Salv=E9tat =
- 1857 :=20
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Uranium oxide (U3O8 or saline oxide) is used in glassmaking to produce =
varied tones of yellow with green glints named " dichroic ". Their use =
in arts to decorate porcelain is rather important.=20
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Vitrifiable uranium oxide yellow for decorating on hard porcelain at =
950=B0C :=20
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Components=20
Vitrifiable uranium yellow=20
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Flux n=B06=20
75=20
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Uranium oxide yellow (Sodium Uranate)=20
25=20
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Composition of the flux :=20
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Components=20
Flux n=B06=20
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Minium Pb3O4=20
60=20
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Crystallized Boric Oxide=20
30=20
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Crushed Quartz=20
10=20
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3) In the book " Fabrication industrielle des Porcelaines " volume II by =
Marc Larchev=EAque - 1929 :=20
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Uranium oxide and various compounds make up part of the artificial =
colouring materials that can be used at 1400=B0C (cone 14) just as =
metals, oxides and compounds of the following elements: chromium, =
cobalt, iron, manganese, nickel, vanadium, tungsten, titanium, gold, =
platinium, iridium.=20
The main uranium ore is pitchblende which contains between 40 and 90% of =
the uranium oxide U3O8, the remainder being made up of sulphur, arsenic, =
iron, lead and a negligible quantity of radium and other radioactive =
elements.=20
Sodium uranate (Na2O (UO3)2.6H2O) is designated by the unsuitable name =
"Yellow uranium oxide ".=20
Uranyl nitrate (a salt with light yellow-green crystals), is used in the =
preparation of various liquid colours (lustres).=20
Other compounds used : ammonium uranate, potassium uranate, uranium =
oxides, calcium uranate, magnesium uranate, iron uranate, manganese =
uranate, lead uranate, etc...=20
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Recipe for the uranium oxide yellow-orange for vitrifiable color =
(between 900=B0C and 950=B0C) :=20
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Components=20
Vitrifiable uranium yellow-orange=20
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Flux n=B01 (also named "rocaille" flux)=20
75=20
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Ammonium uranate=20
25=20
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To mix, melt, crush and dry.=20
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Flux n=B01 :=20
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Components=20
Flux n=B01=20
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Litharge (PbO)=20
75 (or minium Pb3O4, 76.8)=20
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Crushed quartz=20
25=20
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4) In the book "La Bible du C=E9ramiste" Anonymous - about 1965 :=20
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There are three significant uranium oxides :=20
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a) Uranium dioxide or uranous oxide UO2, black, molecular weight 270.14. =
b) Uranium uranate U3O8, green olive, molecular weight 842.42.=20
c) Uranium trioxide or uranyl oxide UO3, red, molecular weight 238.14.=20
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All of these oxides are insoluble in water, soluble in hydrochloric and =
sulphuric acids and are toxic.=20
At high temperature, the uranium dioxide changes into uranium uranate.=20
Uranium oxides are used mainly as colouring materials for enamels, glass =
and porcelain, though the relative instability of the colours restricts =
their use.=20
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a) Uranium dioxide colours glazes in black, jet black or gray in =
reducing atmosphere and yellow in oxidizing atmosphere. It is also used =
to prepare black and brown colouring materials for porcelain.=20
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b) Uranium uranate behaves in a similar way, by giving blacks, browns =
and grays in reducing atmosphere and yellows or reds according to =
circumstances, in oxidizing atmosphere.=20
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c) Uranium trioxide gives greens or blacks in reducing atmosphere and =
yellows in oxidation.=20
This oxide is used to colour under-glazes and porcelains, but its used =
is limited, because of its high price, to lead glass to which it gives a =
vivid orange yellow colour.=20
Uranium trioxide is sometimes used as an agent of crystallization in =
crystalline coloured glazes.=20
One uses it in glassmaking, only or with cadmium sulphide, for the =
production of glass intensely coloured in yellow and orange.=20
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Exemples of recipes for red orange glazes, to be fired at low =
temperature between cone 08 and cone 06 :=20
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Components=20
Possible amounts=20
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Lead carbonate=20
64 =E0 66 %=20
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Crushed silex=20
18 =E0 13 %=20
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Zinc oxide=20
4 =E0 3 %=20
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Black uranium oxide (dioxide)=20
14 =E0 15 %=20
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Kaolin=20
0 =E0 3 %=20
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Another uranium compound : Uranium nitrate=20
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This lemon-yellow salt is used in the composition of lustres, of which =
one of these is prepared with 2 parts of resin soap, 4 parts of hot =
water, and 1 part of an uranium nitrate solution. The uranium soap =
obtained is mixed with an essential oil.=20
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5) In the book "La c=E9ramique de A =E0 Z" par J. Rigaud - vers 1975 :=20
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There are three current forms of uranium oxides :=20
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1)Uranous oxide or uranium dioxide (" reducing " UO2) :=20
Uranous oxide is extracted from pitchblende or carnotite by a process =
based on nitric acid.=20
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2) Uranic oxide or uranium trioxide ("oxidizing" UO3) :=20
Uranium trioxide UO3, or uranic oxide, is obtained by oxidation at high =
temperature of "saline" oxide U3O8. It takes up a yellow color and can =
take up the hydrated form UO3.H2O or UO2 (OH)2, uranyl hydroxide.=20
It can form uranates and diuranates with bases. These products intervene =
in glassmaking and ceramics in the colouring of the vitreous phases and =
the preparation of pigments for high temperature firing.=20
Thus the introduction of alkaline diuranates into glasses leads to =
yellow by transmission, green by reflection; moreover these glasses =
become dichroic and fluorescent under ultraviolet rays.=20
In ceramics, the uranates of heavy metals (Mn, Fe, Pb...) are at the =
base of colors used under glazes, called yellows of uranium oxide, =
obtained in oxidation firing.=20
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3) "Saline" uranium oxide U3O8, the most stable :=20
Saline oxide U3O8 or uranium oxide is found naturally in pitchblende, =
which can contain some up to 80%. U3O8 is used in ceramics and =
glassmaking to make uranates.=20
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6) In the book "Keramic-Glasuren" by Stefanov et Batschwarov - 1988 :=20
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Yellow coloring materials :=20
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The oxide of uramium in the presence of silica or alumina makes it =
possible to obtain yellow hues, but it is not used any more taking =
radioactivity into account.=20
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Yellow glazes :=20
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Lead/calcium or lead/zinc glazes develop a yellow hue by the addition of =
uranium oxide. Just as not very alkaline lead/boron glazes become yellow =
by the addition of 5% of sodium uranate.=20
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Red glazes :=20
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Lead/zinc glazes containung calcium or boron produce an intensive red =
hue by addition of 10% of uranium oxide.=20
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Components :=20
Red Glaze=20
Red Orange Glaze=20
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Minium (Pb3O4)=20
55,5=20
63,0=20
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Potassium feldspar=20
9,8=20
0,0=20
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Crushed silica=20
18,7=20
4,0=20
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Sodium uranate=20
18,0=20
0,0=20
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Uranium oxide=20
0,0=20
17,0=20
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Zinc oxide=20
0,0=20
2,0=20
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Kaolin=20
0,0=20
4,0=20
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Uranium lustre:=20
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Uranium lustre is obtained by the fusion of rosin (colophony), on a sand =
bed, added with 30g. of uranyl acetate, then dissolved in 300 ml of hot =
spirit of turpentine. After cooling the mixture is allowed to settle =
(and decant) and preserved two to three days before the first use.=20
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Smart.Conseil - France / April 2002=20
smart2000@wanadoo.fr=20
Translated by Edouard Bastarache
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Later,
Edouard Bastarache
Irreductible Quebecois
Indomitable Quebeker
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
http://sorel-tracy.qc.ca/~edouardb/
http://perso.wanadoo.fr/smart2000/index.htm
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