Method of decorating ceramic bodies

Claim 1

IN A METHOD OF PRODUCING DECORATED CERAMIC CLAY ARTICLES, THE STEPS OF; APPLYING A FIRST ALUMINA-CONTAINING GLAZE-FORMING COMPOSITION TO SELECTED PORTIONS OF A SURFACE OF SAID ARTICLE, SAID COMPOSITION HAVING SUFFICIENT SOLIDS TO FORM A SUBSTANTIALLY UNIFORM LAYER OF SOLIDS OF A THICKNESS OF FROM 3 TO 20 THOUSANDTHS OF AN INCH BEFORE FIRING, THEREAFTER APPLYING A CONTINUOUS LAYER OF A BACKGROUND GLAZE-FORMING COMPOSITION CONTAINING ALUMINA OVER SAID FIRST LAYER AND UNCOATED PORTIONS OF SAID SURFACE, SAID BACKGROUND LAYER HAVING SUFFICIENT SOLIDS TO FORM A SUBSTANTIALLY UNIFORM LAYER OF SOLIDS OF A THICKNESS OF FROM 5 TO 25 THOUSANDTHS OF AN INCH BEFORE FIRING, AND SIMULTANEOUSLY GLOST FIRING SAID FIRST AND BACKGROUND COMPOSITIONS ON SAID ARTICLE; EACH OF SAID FIRST AND BACKGROUND COMPOSITIONS BEING SELECTED FROM THE GROUP CONSISTING OF: (1) A LEADSILICATE GLAZE CONSISTING ESSENTIALLY OF SUBSTANTIAL PROPORTIONS OF LEAD OXIDE AND SILICA, (2) A LEAD-BORO-SILICATE GLAZE CONSISTING ESSENTIALLY OF SUBSTANTIAL PROPORTIONS OF LEAD OXIDE, BORON OXIDE AND SILICA, (3) AN ALKALI-BORO-SILICATE GLAZE CONSISTING ESSENTIALLY OF SUBSTANTIAL PROPORTIONS OF ALKALI METAL OXIDES, BORON OXIDE AND SILICA AND (4) AN ALKALI-LIME-SILICATE GLAZE CONSISTING ESSENTIALLY OF SUBSTANTIAL PROPORTIONS OF ALKALI METAL OXIDES, CALCIUM OXIDE, AND SILICA; SAID FIRST AND BACKGROUND COMPOSITIONS EACH BEING A DIFFERENT ONE OF SAID GROUP AND SAID FIRST COMPOSITION HAVING SUBSTANTIALLY LESS ALUMINA THAN SAID BACKGROUND COMPOSITION WHEREBY DURING GLOST FIRING SAID BACKGROUND COMPOSITION DEVELOPES A FLUID STATE OF LESSER FLUIDITY THAN THAT OF SAID FIRST COMPOSITION AND WITHDRAWS THEREFROM WITHOUT SUBSTANTIAL DIFFUSION THEREINTO TO UNCOVER SAID FIRST COMPOSITION ON SAID SELECTED PORTIONS, BOTH SAID COMPOSITIONS HAVING OVERLAPPING MATURING TEMPERATURE RANGES AND SAID GLOST FIRING BEING CARRIED OUT WITHIN SAID OVERLAPPING RANGES.