Treatment of a Deruta Maiolica dish, Part II

By Jane Townsend

Editor's note: This continues on from Part I here.

I needed to formulate a plan of proposed treatment now which included removing the rivets, cleaning using a mixture of dry cleaning techniques and damp swabs of deionised water and possibly a cleaning solution of de-ionised water 80%, 20% IMS (industrial methylated spirits) and a few drops of Synperonic A7 (non-ionic detergent)®.

Once I had cleaned the object thoroughly, taking care not to contaminate the break edges as this could inhibit the bonding later, I would need to do a dry run to assess the completeness of the dish and establish a bonding plan.

I was not prepared for how long the cleaning process would take and my estimates for time were way below the actual time taken.

I planned to assemble and support the dish using Magic tape and bond with Paraloid® B-72, an ethyl-methacrylate copolymer thermoplastic acrylic resin, chosen for its reversibility. I would then need to colour fill any missing areas with epoxy resin together with a bulking agent and dry powder pigments, retouching as necessary.

The treatment began with removing the old rivets; some came away with very little pressure whilst others required an application of small pieces of cotton wool soaked in deionised water and placed on the plaster-type substance which was holding the rivets in place. This was then covered in cling film and left for about 30 minutes. This softened the plaster enough to allow the rivets to be gently removed by hand.

The slow process of cleaning began. I used a dry cleaning method for the foot rim and old areas of loss (where it was important to use a very gentle approach.) A dry brush was followed by Groom/stick®, a processed and kneadable rubber, and Wishab Sponge®, a filled and vulcanised latex sponge.

Initial cleaning of the glazed areas on the reverse with deionised water and cleaning solution on cotton wool swabs removed the bulk of the accumulations but a number of particularly rough areas of glaze had trapped dirt and for this I used Autosol®, an emulsion of aliphatic hydrocarbons, cleaning agents and polishing agents. This was a lengthy process using cotton wool swabs and did not completely remove the rougher areas but was successful with the dirt. The residues were removed again with deionised water and cotton wool swabs.

One particularly difficult area was the break edge that followed the firing crack where glaze had partially filled the crack and dirt had accumulated. This needed to be approached with extreme care not to get any of the cleaning materials onto the break edge whilst removing the accumulated dirt, as I did not want it to impede the join when bonding.

My attention then turned to the small shards in the plastic boxes; I separated those from the front and the reverse and surface cleaned using the same methods as before but on a much smaller scale. My skills at making cotton wool swabs improved.

The tiny shards were laid out on Plastazote®, a closed cell, cross-linked polyethylene foam, so that they were accessible and easily identifiable and were able to be placed inside a plastic box during the rest of the process.

Once the cleaning was completed I was able to carry out a dry run, assembling the dish using Magic Tape®, to hold it in place, though due to the size and weight of the dish this did stretch during the process and needed frequent tightening of the tape to ensure a precise fit. I completed a pencil drawing of the bonding plan showing the order in which the sections needed to be assembled to ensure nothing was "locked out," whereby once bonded some parts could no longer be added due to the nature of their shape.

I planned to use Paraloid B- 72 for the bonding, as this material can be removed in future if and when further conservation is required. We had previously made and stored the Paraloid B -72 in tubes as part of our early practical sessions on the course.

Stay tuned for the last part!