Between about 500 A.D. and the late nineteenth century, clay cooking pots associated with the Thule culture were produced in the Arctic region. Ethnographic and archaeological records indicate that these vessels were typically underfired (often even unfired), highly porous, and easily broken. Despite these characteristics, the evidence indicates that they were used to heat water over open fires. In this paper, we examine how Arctic potters were able to produce unsintered vessels capable of holding liquids without disintegrating. We conclude that the application of seal oil and seal blood to the pot's surface was the key to their success.Clay cooking pots were produced and used in the Arctic from about 2,500 years ago until the middle or late nineteenth century (Fig. 1). Although the earliest vessels tended to be thin-walled and relatively well-fired, by 1,000 A.D. these containers were replaced by ones having thicker walls and coarse-textured, soft pastes. Ceramics recovered from the later periods have a marked tendency to crumble and exfoliate, and many were either underfired or not fired at all. The technology of these later vessels differs in nearly every significant way from that exhibited by the typical clay cooking pot found in other areas of the world. In fact, these Arctic cooking pots break nearly every engineering rule about how a ceramic cooking pot should be constructed (see Frink and Harry 2008) and-at least for the unfired or