Fuel has always been an expensive commodity and Islamic potters, like those of today, often sought to economize on its use by packing their ceramic kilns as tightly as possible. Refractory clay tripod stilts were used to keep stacked vessels from sticking together during firing and these left behind small stilt marks that are seen seen on many ceramics. In this case, the bowls accidently shifted before or during firing fusing them together along with the interposed stilts. Sometimes molten glaze dripped down onto objects below. The two large turquoise splashes on a large luster painted bowl in gallery 451 (32.52.3) suggests that it was placed below a blue glazed ceramic in the firing kiln.
[ Daniel Z. Noorian, New York, until 1911; sold to MMA]
New York. The Metropolitan Museum of Art. "Making the Invisible Visible," April 2, 2013–August 4, 2013.
Jenkins-Madina, Marilyn. "Mamluk Underglaze Painted Pottery: Foundations of Future Study." Muqarnas vol. 2 (1984). p. 105, ill. pl. 9c,d (b/w).