an early asbestos-tempered ware. Its distribution is centred on the eastern lake area of Finland. Sperrings ware was another type of early asbestos-tempered ware from about the same time. The style seems to disappear around 200 CE in Finland but continues in Scandinavia. The disappearance is thought to be related to the transition to a semi-nomadic reindeer husbandry lifestyle. Asbestos-containing variants There are two variants of asbestos-containing pottery. The name depends on the proportion asbestos: Ceramics with an asbestos amount of 50–60% are called asbestos pottery; vessels containing 90% asbestos and 10% clay are asbestos ware. Asbestos pottery Asbestos pottery (50–60% asbestos, 50–40% clay) is usually found along with evidence suggesting metal work, i.e. crucibles, moulds, slag, fused clay, artefacts of bronze and copper, and stone sledge hammers. Asbestos ceramic may also have been used as a heat-storage medium. Some of the Fenno-Scandinavian vessel patterns are identical to the Neolithic and Bronze Age Jōmon culture in Japan (jōmon = rope pattern). However, the most common patterns are the comb and pit decorations typical of North-Eastern Europe at the time (Finland). Asbestos ware Asbestos ware (90% asbestos, 10% clay) is unusually heat-tolerant: It can survive temperatures up to 900–1000 °C. The clay is used to make shaping the vessel possible, but with such a low proportion of clay, it is technically not pottery. It is believed that the asbestos ware was used in iron production such as spearheads, arrowheads and artefacts. Found vessels were drilled with many holes. The fact that the reduction of iron ore (FeO3) with abundant carbon generates large amounts of carbon monoxide (CO) may suggest that the drilled holes were used to improve the availability of air (oxygen) to maintain an adequately intense flame for the high temperatures required for the iron smelting. Iron ore is abundant in lakes e.g. in Finland. Clay with hair added Lastly, the term hair-temperature pottery refers to ceramics made of fine, sorted clay, augmented with about 30% finely cut hair and chamotte. It generally contains no asbestos (some samples have insignificant traces). These ceramics were made with similar shape, size, and surface treatment (including decoration) as the asbestos pottery. Hair, when used as ceramic additive, burns away during firing, leaving characteristic thin pores in the resulting pottery. The hair-thermal ceramics' intended use is unknown, but tests of its heat-retaining (insulating) capacity suggests it was intended for some kind of use requiring