RESTORATIONS

Selection from a set of pots from a burial ground
of  the Lusatian  culture in Trenčín

research supervisor: Ivan Cheben, PhDr., CSc.

restored in 2009 commissioned by the
Archaeological Institute of Slovak Academy of Sciences in Nitra

Lusatian culture
Site where findings were made: Trenčín
Original is stored in the Archaeological Institute in Nitra

on the pot the style of  firing  can be seen
the black part is the contact area of branches during the pile kiln firing

set-out  of shards before restoration

plastering

plaster retouching

plaster retouching

during the restoration works

Lusatian culture

shards from the pot on the right,
poured out and ready for restoration

finished pot after
plastering and retouching

decomposed  bowl

the bowl was used as an urn lid

The crack which we did not retouch occurred during firing and  it  was not caused  by  soil pressure. This was proved correct when firing the replicas of the originals. The crack was caused by the firing technique or  by the kiln construction.
With controlled firing and closed copula the bowls are getting colder gradually as a whole  and there is a minimum possibility of  being damaged by cracks. The majority  (90%) of restored pots have got  cracked  mouths. This fault occurs if the pot was fired  in an open kiln or the so called pile kiln /milier. In firing after reaching a certain temperature of about 600 – 800°C they stopped  putting more wood on the fire. As the kiln works like a fireplace  chimney, the draught inside the kiln took out  all the temperature  too quickly and drew the cold air into the furnace and so it sharply cooled the pots in the kiln too. Pots have always got  a thinner mouth than  bottom. That means the bottom was warmed and through its thickness it could keep the temperature. The thin mouth  turned cold sharply, it shrank and that way  it cracked. There is one more possibility here – the pile kiln. When the burning wood around and on the vessel was dying out it dropped and uncovered the vessel and let the cold air in. The temperature difference is 500 - 600°C. The overheated vessel cannot stand that sharp difference in temperature without getting damaged. Another cause of vessels being cracked in the pile kiln firing is uncontrolled rapid temperature rise and also the possibility that a part of the vessel is already  on fire  while the other one is still hidden in wood not burning yet. The pulling power which results from this situation breaks the vessel. Following the firing prints  on a number of vessels we suppose that the pottery from this research which we had a chance to restore was fired in the pile kiln way.

When restoring we found some interesting connections with manufacture. The bowl was made in 5 phases – Picture 1, this fact being confirmed when producing replicas.

In replica production we also verified  the theory according to which the bowls might  have been made by means of moulds. That is why we tried to make  a big bowl (60cm high) into a  plaster mould composed of several parts. As the weight  of the bowl was carried by  the mould, the bowl could be modelled in one time. After taking the bowl out of the mould we wanted to clean its outer side. During the cleaning  it started to get deformed at first in the part of phase 1, Picture 1. So we put it back to the mould. Then in the mould it started to sink in phase 3.  We succeeded in saving the bowl but not its form. Manufacture of big bowls into moulds  is complicated and the whole process of drying and caring about  the bowl equals the time needed for hand-modelling  from clay coils or flat slabs. Modelling from coils or slabs of clay  we can also avoid problems with making the moulds, their storing or transport and moreover, from the technical point of view, the manufacture of bowl moulds as much as  60cm high is demanding. There also occurs a problem whether the manufacturers of originals knew the technology and the material which they would use  for mould production. Variety of shapes and sizes of individual  bowls does not confirm using the moulds.

As for the production from slabs  and  coming  out of  my own experience I  think that this technique can be applied only in phase 4 and 5.  It is because the pressure of the slabs  themselves goes vertically downwards and by no means loads the already modelled part. The weight pressure in phase 1 and 2 tends to mash the soft clay outwards and so cracks occur and  being not repaired in time they keep running to the bottom of the bowl which consequently falls apart. Vice versa  in phase 3 the soft clay closes inwards so that it completely caves inwards and even pushes the bulge out.

This means there could be left  even a day´s intervals. If the surrounding area was held  moist enough  or if it was dry (fireplace in a hut, dry weather) it is possible to carry out  maximum 2 phases in one day. A sudden dryness gets the water dry just from the surface of the wall, however inside it  still stays soft and fragile. The bowl in Picture 1 was presumably  manufactured with a day´s intervals because then the clay wilts properly also inside the wall and in a longer interval between modelling more water will vaporize and thus the vessel will get smaller. This can be seen in phase 4 ( it got dry sooner) which is wider than phase 5. That one  was modelled  moister, so with bigger water content. During the drying process  phase 4 was almost dry, whereas phase 5 contained  still a  considerable amount of water. That is why the mouth is narrower.

picture 1

Individual phases of manufacture

Phase 1: modelling a cake as a base and bottom of the bowl. Attaching  on coils of clay to about half the distance  from maximum of the bulge.
Phase 2: affixing coils of clay up as far as the maximum of required bulge (maximum width of the future belly of the bowl)
Phase 3: completing modelling the belly up to the “shoulders of the bowl”
Phase 4: forming the neck up to the half of its full height
Phase 5: completing the neck to the final height of the mouth

original  placement

Peter & Pavol Vozárik
Vojtecha Zamarovského 59/1
Trenčín,  911 01   Slovakia

Tel.: +421 902 322 927
Email: peter.vozarik@gmail.com