It's crucial that clay and glazes be matched for firing temperature. Both low- and mid/high-fire clays can bisque at cone 04, but the recommended glaze firing range will be different for each. Glazes need to mature in the recommended glaze firing range for the clay. Fire the glaze too low and it won't mature, too high and it may discolor or flow too much. Fire the clay too low and it won't vitrify enough to be durable, too hot and the clay will soften and distort or may even melt. Also, we always recommend firing test tiles to verify that the glaze is a good "fit" for the clay. Most of the time commercial glazes and clays work together, but it's still possible for them to not have the same rate of expansion and shrinkage, which can result in glaze crazing or shivering.
Many glazes can fire hotter than the specified firing range, but the glaze will typically flow more, and certain colors may fade, darken, or otherwise change in appearance. Consult the manufacturer's guidelines to determine whether the glaze you have in mind can take a hotter firing and be prepared to fire test tiles to make sure you know what to expect before applying to actual ware.
This is not a good idea. Firing the clay hotter than the recommended range can destabilize or even melt clay that's meant for lower temperatures. Firing the glaze too low will not provide the heat necessary for it to mature to its expected appearance. The clay and glaze should be matched for firing temperature.
No. Please verify prior to purchasing that the glaze is acceptable for dinnerware if that is your intended use.
Absolutely. It's always a good idea to fire test tiles with your specific clay to see the results you can expect before applying to your finished piece. The photos on our website will typically only show you the results with a single clay body.
Ceramic glazes can look very different in liquid form compared to the fired result. Don't be alarmed if the liquid color is quite different.
Sometimes you can. Look at the product description for the glaze to see if it notes that colors can be mixed. Otherwise, just know that any mixtures will be experimental; yellow+blue may not give you green for example, and take meticulous notes so you can reproduce any favorable outcome.