Following on from the Keeping a lid on it blog post, Jill Saunders reveals more about the outer side of the iron coffin lid and its decorative detail.
By marketing on 19 Jul 2012
We positioned blocks of Plastazote strategically on the table ready to turn the board onto so that the weight could be evenly spread and the iron pegs could be clear form the ground. Once the correct way up, we could see the extent of detail on the exterior surface. There was a great deal of dust but beneath this we could see remains of a border decoration (suspected leather), the area where the coffin plate had been (impression preserved in suspected leather), and a smaller area above this which seemed to outline another second plate.
In the middle of this second, smaller plate outline there was still a pin with a fragment of metal left (which seemed to be copper alloy). We were delighted to have such a wealth of material remains but the features were thick with dust and would need a good clean before any consolidation or lacquering could take place. Though some of the suspected leather border seemed secure and firmly attached to the iron below, in places the adherence was poor with parts lifting off. It is important to remember that archaeological materials often bear little resemblance to materials as they were originally made and can have very different qualities. The majority of the ‘leather’ was very different to fresh leather and was brittle, probably due to degradation and infestation with metal salts. Brittleness is of course synonymous with fragility, so we had to think careful about how we could go about removing all the dust without damaging the material.
We were happy that the brush and vacuum method used on the inner surface would be effective and gentle enough for clear areas. We experimented with cleaning through mesh netting in places where there were features so that if they were broken they would be held in place and could be easily reattached (Fig. 6). We found however that this inhibited the action of the brush too much and did not allow effective cleaning so we proceeded carefully without it. Of course we placed netting over the end of the vacuum so that if anything was dislodged it would be saveable. I should note that these are special object vacuums – much lower suction than the domestic variety!
Removing the dust made a significant difference and features stood out much more clearly from the iron surface. However during cleaning we noticed some pieces of decorative detail were loose or detached. As we could see clearly where they had come from, we decided to re-attach them using a standard conservation-grade adhesive. This proved quite difficult though as deformation meant that there was very poor contact between the broken off pieces and the surface from which they had come. They were very brittle so it would not do to try to push them down to improve contact – however gentle, this would only break them. We found that applying the adhesive around the edges of the fragments, as opposed to beneath them, succeeded in holding them in place; and we knew that the lacquer which we planned would further secure all features.
Watch this space for the next entry covering how scanning electron microscopy helped us understand different materials on (and in!) the coffin: Name that fibre!