Reheat the pottery to melt the glaze and seal your object. Depending on your clay, the size of the object, and the glaze, you may need a kiln that hits 2500° Fahrenheit (1148° C).
Overnight, warm up your kiln at very low heat. Spend two hours at low heat (an increase in temperature of no more than 200°F per hour) and then two hours at medium heat (an increase in temperature of no more than 300°F per hour). Finally, finish at high heat (an increase in temperature of 300 to 400°F per hour) until the required temperature has been reached.