Vanadium is the basis of most ceramic yellows, and it is almost never used raw in a studio. What potters buy is a vanadium-tin or vanadium-zirconium stain, in which the vanadium is already combined and stabilised, because raw vanadium pentoxide is both weak as a direct colourant and a material that needs careful handling.
Why yellow is difficult
Yellow is one of the hardest colours to achieve in a high-fired glaze, because most yellow-producing materials burn out, shift or go muddy at stoneware temperature. Vanadium combined into a stain survives, which is why almost every stable ceramic yellow in the supplier's catalogue is a vanadium stain rather than a raw oxide.
Raw against stain
Raw vanadium pentoxide added to a glaze gives weak and unpredictable colour, and it carries handling requirements that make it a poor choice for a small studio. A commercial stain gives a strong, repeatable yellow at a few percent, has been tested across a firing range, and is the practical purchase for anyone wanting a yellow glaze rather than a research project.
Handling, if you do buy it raw
Vanadium pentoxide is among the materials that need real care: a fitted respirator, good ventilation, gloves, and wet cleaning of any surface it has touched. It is stated here because it is listed on supplier price lists alongside gentler materials and its position in the catalogue implies nothing about how it should be handled.
Getting a yellow without it
Commercial yellow stains, some titanium and rutile effects, and low-fire glazes where more colourants survive are the practical routes. At earthenware temperature the palette is much wider, which is one of the standing arguments for firing low if bright clear colour is the point of the work.
Questions people ask about vanadium pentoxide
How do I get a yellow glaze?
With a commercial vanadium-based stain at a few percent. Raw vanadium pentoxide is weak as a direct colourant and needs careful handling.
Why is yellow hard in ceramics?
Most yellow-producing materials burn out or go muddy at stoneware temperature. Stains stabilise the colour so it survives.
Is vanadium pentoxide dangerous?
It warrants more care than most materials on the shelf: a fitted respirator, ventilation, gloves and wet cleaning.