These cone 6 mugs use an 80:20 Alberta Slip:Frit blend inside and out (the outside one has added rutile). Made around 2014. The incised wheat decoration as a dead giveaway that the mug is made by Tony. He has made this type of mug for decades and there is a good reason: continuity of testing. By making the same kind of ware each time he tests a clay, going through the same procedures he has done a thousand times, he can more easily spot differences in the way they perform.
A type of decoration done on pottery. Designs are carved into the surface of the leather hard ware and often covered by a thickness sensitive glaze.