All of Holly McKeen's unique pieces are made of high quality porcelain or stoneware clay, thrown on the potter's wheel, or hand-built, and fired in a kiln over a period of up to 18 hours. The pottery is first "bisquit" fired to just over
1800 degrees Fahrenheit, in preparation for glazing. Holly mixes all of her own glazes with careful formulations and applies the glazes by dipping, pouring or spraying. Many pots have up to four different glazes layered for unique and beautiful effects. Once the glazes are applied, the pots are again fired up to a temperature of 2300 degrees fahrenheit. All of the functional pottery is dishwasher and microwave safe and none contain toxic materials.
Crystal glazes are a relatively new phenomenon and are particularly complex to master. Very few Potters are interested in dealing with the difficulties involved in producing these glazes. In order to "grow" the crystals, the glazes must be fired to over 2300 degrees F, until it runs right off the pot.
Each piece must have another specially thrown “glaze catcher” pot, fastened to the bottom of the pot to hold the run-off glaze so that it does not ruin other pots or the kiln shelves.
The crystals, themselves, actually form randomly in the glaze in a chemical reaction during the firing and cooling process - if all conditions are just right. They grow from small nuclei created during the melting process when silica and zinc come together to form zinc-silicate. The complicated firing and cooling schedule allows for the crystals to "grow" at the optimum kiln temperatures during hold periods of 3 to 5 hours depending on the glaze formulation. The glaze catchers are then carefully removed by torching and grinding the bottom of the pots. Each pot will have different forms and colors of crystals, depending on the glaze composition, the firing schedule, glaze thickness, and method of application.
The use of various coloring oxides creates different colored crystals. There are so many variables in creating crystalline glazes that every kiln load has new surprises. Not all pieces work out, but every piece is truly one-of-a-kind, as the crystal formations cannot be duplicated! These are very beautiful and special pots, true collector items!