Different kinds of temper can attach various properties to ceramics.
Proper kind of admixture increases the resistance from breakage during
firing, reduces the shrinkage of clay paste and makes the process of vessel
modelling and drying easier. The composition of clay paste is a rather
variational and inconstant property — and it can include a combination of
different materials. Some components among them can sometimes play a
non-functional role.
There are on the one hand certain conservative tendencies in changing
of clay paste composition in ceramics of Early Metal Period in the eastern
part of the Gulf of Finland region. There are such types of temper, which
attach special properties (as asbestos) or have special cultural importance
(as chamotte). Against the background of changing elements in vessel shape
and decoration, a tradition to add these kinds of temper seems very stable.
On the other hand, clay composition with these components often becomes
polycomponent. Probably as a result of cultural contacts there are added
some other mostly organic tempers (wool, feather, shell). Perhaps in case of
lack of some hard-to-get substance (asbestos) it could have been replaced by
others, and the tradition itself could decay until it disappeared.