Black firing in smoke

The Barcelos specification explains reduction firing in a sentence: black ware is fired almost like red ware, differing only in that the kiln is fully smothered when it reaches maximum temperature, having just been fed with wood. From then on no oxygen enters the combustion chamber, carbon forms and impregnates the pieces, and they turn black. The Saber Fazer programme defines it as combustion with an oxygen deficit, leaving pieces between black and grey, and says the technique is kept whether the kiln burns wood (Molelos) or gas (Olho Marinho, Carapinhal).

The older methods burned in the ground. Saber Fazer names the soenga (Bisalhães) as the most ancestral and the forno de poço, a pit kiln (Vilar de Nantes); both could be individual or communal, with a shared day of soenga. Diário de Notícias describes old kilns opened in the earth, burning gorse, pine needles and carqueja, then smothered with the dark earth that gives the black colour. In Molelos, Lusa reports the soenga as the oldest way of firing there, in a circular pit dug in the ground that works as a kiln.