Summarized from M.R. Popham:

Early stage:Fine clay with a few small white and black grits. Bluish white to light grey slip. Paint black to brown black.

Normal stage: Same clay as earlier but coarser. Light grey to buff slip. Paint dark brown.

Late stage: Coarser and micaceous clay. Buff to brown creamy slip. Paint is dark brown. 

Most common shape is the hemisperjical bowl with wishbone handle and rounded bottom. Other forms are large bowl (crater), jug, bottle, jar, cup, alabastron that are very rare. 

Motives are ladder lattice, lattice hooked chain, ladder lattice dotted row and ladder lattice, parallel line.