Petrography

The Conservation and Restoration Laboratory—J. J. Gottlieb, Conservator

The Leon Recanati Institute for Maritime Studies is equipped with a conservation and restoration laboratory. The lab’s main purpose is to receive and preserve archaeological artifacts recovered from the various archaeological excavations conducted on land, the coastal plane and underwater. The lab offers technical and scientific support to researchers of the Institute, the department of Maritime civilizations and visiting scholars. The conservator offers professional treatment designed for the specific needs/requirements of the archaeological material culture, i. e., pottery, glass, metals and stone.

Ceramic vessels are sorted, restored and the photographed to produce high quality images suited for publication.  Pottery from a marine environment requires special attention. These have to undergo de-salinification before restoration. This is done by submerging the objects in a series of distilled water baths until a saline or conductivity meter shows minimal amounts of soluble salts. At times, ceramic vessels, predominantly from land digs, is incrusted with a calcareous layer. This layer is removed by submerging the fragments in a dilute solution of acetic acid. Then washing them thoroughly to remove any traces of the acid. Once this process is complete, the pottery fragments are sorted, and restoration can begin. 

The state of preservation of metal objects such as coins, jewelry and various tools is assessed and treatment is selected.  It is common for bronze and iron objects to arrive at the lab in various states of degradation. The main policy is to avoid treating these alloys with chemicals. When possible, mechanical treatment is preferred. This is done using a particle blast machine, shooting inert plastic particles. The pressure of this bombardment can be monitored so as to inflict as least damage to the object as possible. Iron objects from a marine environment pose a challenging problem. These are usually encrusted with a natural-forming conglomerate around the object. Before any major treatment is to be performed on these items, they are X-rayed to determine the context and state of preservation. At times, only the "negative" of the object survived and the actual artifact has disintegrated.  Small objects may be manually cleaned under a stereomicroscope. With lead objects there is, at times, a build-up of calcite. This may be removed with a diluted acid or very gentle mechanical cleaning as the lead is very soft.

Once the metal objects are treated, they must be stored in optimum conditions of humidity and temperature.

The Petrographic Thin-Section Laboratory—J. J. Gottlieb, Petrographer

In this laboratory, thin-section slides for micro-morphological analysis are produced. Various materials such as ceramics, mortar, stone, soil samples and other minerals undergo a process of polymer impregnation in order to consolidate the brittle or friable sample.  This is done by introducing a solution of polyester and styrene, with its hardener, into the sample by vacuum.   This polymer enters the microstructure of the fabric thus facilitating the cutting, grinding and polishing of the specimen once cured.  Each sampled is cut using a Hilquist diamond saw with parasol as the cooling agent. The sample is then ground and polished to the thickness of25- 30 µ. The researcher wanting to determine the mineralogical context of the sample then analyzes these slides. Micro-morphological analysis may determine, in the case of pottery for instance, the provenance of the fabric, or the mineralogical content in the case of a soil sample.

© 2017 The Leon Recanati Institute for Maritime Studies University of Haifa, Mount Carmel, Haifa 31905, Israel Tel: 972-4-8240600, 972-4-8249819 | Fax: 972-4-8240493 | E-Mail: maritime@research.haifa.ac.il