Gabriel Tejeda on mon 28 apr 03
An acidic metallic oxide which produces yellow coloration in amounts to =
10%. Its color in generally weak, but can be strengthened when fritted =
with tin and zirconia. Although yellows can be prepared with antimony, =
vanadium is stable at higher temperatures. From =
:(http://www.digitalfire.ab.ca/cermat/oxide/v2o5.php)
This is my formula: Cone 1-2 Oxidation-Gas kiln
RO unity Analysis Mole%
CaO 0.46* 0.12 13.64
Li2O 0.10* 0.01 2.89
MgO 0.02* 0.00 0.60
K2O 0.04* 0.02 1.31
Na2O 0.16* 0.05 4.87
ZnO 0.13* 0.05 3.78
SrO 0.09* 0.04 2.70
TiO2 0.01 0.00 0.16
ZrO2 0.01 0.00 0.20
Al2O3 0.22 0.10 6.44
B2O3 0.13 0.04 3.93
P2O5 0.00 0.00 0.01
SiO2 1.99 0.55 59.22
Fe2O3 0.01 0.01 0.25
I tried the Trixaxial blend (Opacifier Test Series) from David Hewitt =
Pottery website(http://www.dhpot.demon.co.uk/)
I tried the 6% Vanadium Pentoxide, and didn't get any yellows. it was =
almost transparent and off white with the opacifiers, why? am I missing =
an oxide in my formula that will triger the yellow? =20
Thank you for your time.
Gabriel Tejeda
David Hewitt on tue 29 apr 03
Gabriel,
I am currently running a number of tests using vanadium pentoxide and
trioxide. These are at cone 6 and on porcelain clay as a buff stoneware
tends to make any of the colours that much 'muddier'.
I have also read the general statement that you have quoted in your
opening paragraph regarding tin and zirconium. My experience with
adding tin is that it produces a very pale off white cream colour.
I have been adding up to 10% vanadium to a number of different glazes
and find that the colour can range from pale blue, mauve, green, fawn
and brown. Generally all are pale. Clearly the basic oxide mix has a
significant bearing on the result as well as the alumina.
I have not produced a real yellow colour, the nearest being a fawn
colour. Also with a relatively low alumina there is an attractive orange
peel surface finish.
Looking at your recipe I would leave out the tin, zirconium, strontium
and titanium, increase the MgO and try a line blend with up to 10%
vanadium.
If you can work to cone 6, I could let you have the recipe that for me
has given the fawn colour - the nearest I have got to a yellow.
David
In message , Gabriel Tejeda writes
>An acidic metallic oxide which produces yellow coloration in amounts to 10%. Its
>color in generally weak, but can be strengthened when fritted with tin and
>zirconia. Although yellows can be prepared with antimony, vanadium is stable at
>higher temperatures. From :(http://www.digitalfire.ab.ca/cermat/oxide/v2o5.php)
>
>This is my formula: Cone 1-2 Oxidation-Gas kiln
>
> RO unity Analysis Mole%
> CaO 0.46* 0.12 13.64
> Li2O 0.10* 0.01 2.89
> MgO 0.02* 0.00 0.60
> K2O 0.04* 0.02 1.31
> Na2O 0.16* 0.05 4.87
> ZnO 0.13* 0.05 3.78
> SrO 0.09* 0.04 2.70
> TiO2 0.01 0.00 0.16
> ZrO2 0.01 0.00 0.20
> Al2O3 0.22 0.10 6.44
> B2O3 0.13 0.04 3.93
> P2O5 0.00 0.00 0.01
> SiO2 1.99 0.55 59.22
> Fe2O3 0.01 0.01 0.25
>
>
>I tried the Trixaxial blend (Opacifier Test Series) from David Hewitt Pottery
>website(http://www.dhpot.demon.co.uk/)
>I tried the 6% Vanadium Pentoxide, and didn't get any yellows. it was almost
>transparent and off white with the opacifiers, why? am I missing an oxide in my
>formula that will triger the yellow?
>
>Thank you for your time.
>
>Gabriel Tejeda
--
David Hewitt
David Hewitt Pottery
7 Fairfield Road, Caerleon, Newport,
South Wales, NP18 3DQ.
Tel:- +44 (0) 1633 420647
Fax:- +44 (0) 870 1617274
Web:- http://www.dhpot.demon.co.uk
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