Celadon is not necessarily a glaze that crackles. Celadon is a pale green to grayish green glaze that resembles the color of natural jade, and was originally a glaze developed a thousand years or more, give or take, in China or Korea, and has specific and characteristic chemical components.
One of the most important aspects of choosing a glaze is a quality known as "fitting the clay".
Glass workers of dichroic glass or lamp work glass know that you have to match the kinds of glass you are using. Different kinds of glass have different physical qualities and limitations, and those that differ too greatly can not be mixed without a consequence of failure.
Well, clay and glazes are sort of the same way. What kind of clay is it? Earthenware, stoneware or porcelain? At what temperature is it being fired? (earthenware at low, porcelain at high). And so on. When you purchase commercially prepared glazes, the glaze not only has to partner with the kind of clay, but also the firing temperature of the kiln (cone). Talk to the supplier.
Also, lead-containing glazes are colorful and beautiful, but should not be used on pottery that is used to serve acidic foods like wine or fruit, as the lead, under these circumstances, can leach into the food. -- Jabbadah.