Cobalt OxideTOXIC! Use with Caution! Cobalt Oxide is used as a glaze and slip colorant and brushing oxide decoration. It produces consistently strong blue tones in small amounts. Because of its intense coloring power and larger particle size, it can cause a speckled effect. One full bag is 55 pounds. Sold in full and half pound increments. Click on link for Quantity Discounts. We reserve the right to change pricing without notice due to current market conditions.