425 (10)

398

Dress Accessories

surfaces. Many objects had evidence of tin coat-ing (colour pis 4G & 5A), both on the surface of the iron and in the corrosion layers. Even objects in apparently good condition were often very fragile. Despite the slorage of the objects in desiccated conditions, some of the untreated iron shows signs of new or continuing corrosion. Smali flakes and rust-coloured bubbles and blisters have been noted on a number of objects. The fine, black appearance of the ironwork does not always survive in desiccated storage. lt has tended to alter to a dull-brown colour within a few years.

Lead, leadltin alloys and tin The different metals of these cast objects could not be distinguished visuaily. Many of them were in excellent condition. An even, dark-grey patina of lead sulphide on well-preserved metal was often only obscured by dirt. Other lead/tin alloy objects had the dull-gold coloured corrosion as described above for the copper-alloy objects (colour pis 1E & F and 6B & E). This layer was some limes so thin and smooth that here too it was hard to believe that it had not been deliber-ately applied. As with the copper-alloy items a great deal of surface detail had survived, including casting flashes. Some objects were, however, in a poor condition; a hard, cream-coloured corrosion was present in pits and fissures. These objects were brittle and fragile.

Silver

Only six silver objects were treated. A thin and brittle, often tenacious dull-gold to black coloured corrosion crust was common. The underlying metal surface was often etched, pitted and very soft. Though the sulphide corrosion sometimes conformed closely to the shape of the object, it occasionally obscured fine detail, such as the inscription on brooch no. 1337 (colour pl 6C, shown after cleaning).

Settings

Several copper-alloy and lead-tin brooches, mounts and finger rings had been set with glass stones, some of which have survived (colour pis 4F, 6E & 7A). Simple microchemical tests on the white powdcry setting media indicate the pre-sence of carbonate. In common use at this time was either putty - a mixture of a drying oil and whiting (calcium carbonate), or a mortar - calcium hydroxide, which reacted with carbon dioxide to give calcium carbonate (AML). A lead-tin mirror case (no. 1710, colour pl 12B) retains the setting medium, which had been coated with black lead, together with traces of the glass.

ORGANIC MATERIALS

Objects madę out of leather, wood and bonę and textile fragments were prcserved in the water-logged layers. Fragments of these materials were also found in association with metals, eg leather between copper-alloy buckie plates and wound silk threads on both copper and iron wire decora-tions (nos. 1455 etc, figs 194 & 195).

Selection, treatment and storage

Once excavated, this materiał is very vulnerable to both physical change, shrinkage and cracking, and to further microbiological attack, eg fungal decay. It is also difficult and bulky to storę in an untreated State for any length of time. For these reasons it was decided to conserve all the organie finds.

The wet wooden combs were often incomplete and very fragile, especially the teeth. The surfaces were soft and degraded; the cores stronger and less degraded. Some of the combs excavated in the early seventies had been allowed to simply air-dry and were brittle and fragile. The leather purses and straps were in generally good condition: brown in colour and soft though fragile and easily torn. Sometimes the leather had clelamin-ated indicating a breakdown in structure during burial. Textiles were dark in colour, fragmentary and very fragile.

Objects were carefully washed and examined for evidence of surface decoration such as gilding or paint, for example traces of yellow pigment were noted on comb no. 1745. All wood and leather items were accurately drawn prior to treatment to provide records to monitor any shrinkage or distortion. Wood species were routinely identified by specialists before treatment. The conservation of wet organics has evolved greatly over the last fifteen years. The aim of all the treatments is to dry the materiał without causing excessive shrinkage and avoiding