GRST 321 Lecture 25: November 17

• School: University of Calgary
• Department: Greek and Roman Studies
• Course: GRST 321
• Professor: Lesley Bolton

Document Summary

Black- and red- figure vase: extremely popular type of pottery from the ancient world ad we have thousands of these artifacts. Sintering occurs to change clay into ceramic pottery and accentuates the red iron oxide (haematite colour intensified). But we want black: change the environment to be a reducing environment (lacks oxygen). Can do this by decreasing ventilation and/or add wet wood that smokes lots and displaces oxygen: haematite turns to magnetite, which is black. Now everything is black, and the temperature should be around 900-1000 degrees celsius, at which point the potter knows that he will reach the vitrification point of the black slip. Where the slip remains will turn glossy and the colour will be irreversible: rei(cid:374)trodu(cid:272)e o(cid:454)(cid:455)ge(cid:374), (cid:449)hi(cid:272)h (cid:272)a(cid:374)"t get past the (cid:271)la(cid:272)k slip. Those areas re(cid:373)ai(cid:374) (cid:271)la(cid:272)k. the only place the oxygen can turn the magnetite back to haematite is on areas not covered by the slip.