Iridescent Glazes

As a ceramics expert and connoisseur, Charles Lang Freer encouraged the fledgling Pewabic atelier. Perry and Horace J. Caulkins enjoyed the benefits of Freer's criticism and generous access to his important collection of Asian and Near Eastern ceramics. It was at Freers behest that Perry began experimenting with iridescent glaze effects and, from these experiments, developed her palette of six iridescent glazes. Perry began her iridescent glaze experiments about 1902 and achieved success in 1906 with a small bowl she termed "First Iridescent 1906". [21] The Parker Collection has a fine example of this early iridescent glaze from 1906 (see: 1972_2.195) .

The strongest possible influence in our endeavor came from our acquaintance with Charles L. Freer. He came to our work-shop pottery now & then, & his selections & approvals did altogether more to direct our aims\destiny than any other influences. He seemed to like the first little tests & found parallel types in his own collection, especially in certain Japanese glazes. [22]

Perry developed a unique frit formula which was used for each of her six iridescent glazes, which she called 1A, 2A, 3A, 4A, 5A and 6A. The base glaze was fritted or melted in a small high heat furnace and allowed to drip into a pan of water to solidify. The resulting glass substance was dried for several days and then ground into a fine powder in a ball mill. To create a particular iridescent glaze, Perry added the following materials to her base frit for: 1A silver carbonate; 2A zinc oxide, copper oxide, carbonate of silver and tin; 3A subnitrate of bismuth, carbonate of silver and carbonate of copper; 4A carbonate of silver and copper sulfide; 5A copper sulfide and silver sulfide; and 6A zinc, tin and copper sulfide. Her iridescent glazes were applied singularly or in combination over bisque ware or glazed ware depending upon the desired effect. They were then fired in the Revelation Kiln using kerosene oil for the reducing agent. These iridescent glazes matured at pyrometric cone 08-07 (950-990 °C) and were reduced at cone 020-019 (650-660 °C). [23]

{Illustration #5: Mrs. Stratton potting.} Those iridescent glazes that most pleased Mr. Freer were subdued, often transparent matt with slight crystallization and a delicate crackle (see: 1972_2.195 , 1955_1.147 , 1972_2.161 , and 1972_2.190 ). Some had an iridescent volcanic flow over a black matt (see: 1972_2.182 , 1955_1.146 , 1972_2.184 , and 1972_2.170 ). Freer delighted in comparing the subtle colors and textures of a Whistler painting with those of an ancient piece of ceramic or a selected example of Pewabic Pottery to show the artistic kinship. For Freer, these relationships were nothing short of cosmic in nature. Perry embraced Freer's interest in nuances of texture and color, sometimes at the expense of form. While both Strattons experimented with form, the most important contributions of Pewabic Pottery to ceramic art are the innovative iridescent glazes Perry developed. She wrote of her work:

My Iridescent has been developed from a fortunate beginning into the present stage, always uncertain but less so each time;

It is an expensive glaze to make.

I have received honorary degrees from the U. of M. and Wayne University mainly from the qualities beyond the usual in the various uses of my Iridescent glazes.

In quality this glaze approaches the nearest to the effect produced by the long rest in the earth of the pottery of Persia and China and it is from the experts in these fields that I have received the greatest friendship and encouragement which, of course, is one of the most satisfactory experiences of my life. [24]