The pottery kilns

Orvietan ceramic between the Medieval and Renaissance periods

The medieval Majolica* workshop

The first room was used for ceramic working from the 13th to the 16th centuries.
After kiln-firing, some ceramics were rejected because they had defects in their shape or decoration. These rejects are displayed along the walls, and next to some of them you will find reconstructions to show what the original items would have looked like.
A part of the room has been directly dug out from the tuff rock; the stone has become white due to prolonged heat exposure. That was the ceramic workshop’s kiln.
Some metal studs in the floor indicate the position of blocks of tuff and brick that were used to enclose the firing chamber.
The blocks would be partially heat-damaged, and the chamber would need to be reconstructed each time the objects were put into and taken out of the kiln.
The rectangular recess in the corner is the opening to a chimney and it leads up to a small alcove which acted as a valve, permitting the kiln to be cooled and the heat to be distributed to the rooms in which the newly made clay objects had been
left to dry.

*the term Majolica refers to Italian earthenware that has been opaquely glazed using a tin oxide and is usually highly decorated

The Renaissance muffle kiln

The structure found under the floor of the swventh room formed the base of the muffle kiln, the kiln used for the third firing of the ceramics. The difference between this kiln and the one you saw in the first room, cut into the rock and used for the first and second firings, is that this one is entirely constructed from bricks and blocks of tuff and no mortar was used. Its design was that of a reverberatory kiln, which Cipriano Poccolpasso mentioned in his book “I tre libri dell’Arte del Vasajo” and which were used in central Italy between 1400 and 1500 AD. Objects that underwent the third firing were referred to as lusterware and were the famous Renaissance ceramics known for their iridescent colours and shine, and they were considered as precious as gold and gemstones.
To give a better understanding of the main types and the variety of Orvietan medieval and renaissance ceramics, we have compiled a collection of fragments in the four display cabinets on the wall close to the kiln’s remains.
Some lusterware fragments and numerous original tools are also exhibited.

The ceramic finds

A small summary of the fragments found in the two kilns and exposed to the Pozzo della Cava:

  • Glazed ceramics (end of the 13th century): The objects were painted and then immersed in lead-oxide based crystalline, before being fired at approximately 920°C.
  • Ancient majolica (14th century): After being first fired (about 970 ° C), the object was immersed in enamel (crystalline with the addition of tin oxide), decorated in green (copper) and brown (manganese) and then fired a second time (at about 920 °C).
  • 15th century majolica: The same technique of the previous century; blue, orange and yellow were added to the green and brown decorations.
    Variations: sometimes a zaffre blue relief was added; in some cases “false majolica” were produced, where the white enamel was substituted with liquid clay called slip, and following its decoration was covered in crystalline.
  • Lusterware (16th century): After the second firing, the majolica was again decorated with gold and ruby red glazes, then fired a third time (about 750 ° C).

The tools

The original tools and the remains of the materials found in the two furnaces are also very interesting:

  • Terracotta and stone moulds for shaping clay: head and tripod moulds in terracotta
  • Tools for shaping clay using the wheel: terracotta and metal slats, engraving rollers
  • Objects for ceramics decoration: metal salts for lustre, samples of frits [sand and lead mix for decoration]; ampoules for decorative oxides…
  • Tools used in the second Majolica firing: terracotta nails used to support the first plate or bowl in each pile; terracotta tripods and fragments of cooking racks

Curiosity

  • When the medieval kiln was unearthed in 1985, it demonstrated that Majolica production existed in Orvieto between 1400 and 1500 A.D., wrongly considered a dark age in Orvieto’s ceramic history.
  • When the muffle kiln was unearthed in 1998, it shed new light on Orvieto’s ceramic history, demonstrating that Orvieto also produced lusterware.
  • A comparative study of the fragments found in the Via della Cave district has shown that practically all of those originating from the right-hand side of the road date between 13th to 15th century AD when there was an extensive system of ceramic kilns from which goods were exported to the main Italian cities and abroad. The discovery of the “Cavajole” kiln has enabled the manufacture of many majolica wares to be attributed to Orvieto, whereas before they were thought to have been produced in Viterbo or Faenza.