The next step for the Egyptian jar was un-gluing all the fragments …to glue them together again.
We had two different cases: fragments that remained adhered together and fragments that were already separated, bearing remains of an old adhesive on their edges. The old adhesive had to be removed since it had many negative issues. First, it prevented the fragments from being joined back together by creating an unnecessary thickness at their junction. Moreover, when reconstructing the ceramic, the old adhesive prevents the fragments from fitting together well.
This old adhesive had a light brown color and after a few tests, it was found to swell when warm water was applied on it.
Here is what it looked like:
To remove the adhesive from the break edges, we used a Preservation Pencil, a tool looking like a pen and emitting water steam. Once softened, the adhesive was very easily removed with a scalpel or a brush.
And here is the result :
For the fragments still adhered together, it was a little more difficult since the water had to penetrate inside the jar but not too much because of the water-soluble ink on the surface. Compresses, or poultices, of water were applied on the interior of the ceramic, to cover the breaks. Most of the fragments fell apart quite quickly contrary to areas where the jar was very thick.
Now the building could begin ! … well almost since it was necessary to plan precisely how to proceed and in which order to arrange the fragments. First, we had to find where each of them was going, to estimate the losses. For that purpose every fragment was given a number and they were located on a map so as to keep track of their location.
Then the gluing really began, using the conservator’s favorite adhesive: Paraloid B72, diluted in acetone.
The more the jar grew, the more it needed a support, first on the outside, since its bottom is rounded….
…then on the inside to prevent it from collapsing on itself because of some particularly heavy fragments.
Losses in the ceramic had to be filled at the same time as the gluing to provide structural support to the jar and prevent it from collapsing. Moreover those areas to fill would have been difficult to reach once the gluing was complete.
There was one large loss that definitely needed to be filled since one of the surrounding fragments was holding by only a few millimeters to another one.
Filling this area was a bit tricky. The fill material needed a support to be applied on the jar. Japanese tissue paper was glued inside of it and strengthened by applying several layers of Paraloid B72. It also needed to be shaped according to the curve of the jar.
The fill material used is a mixture of Paraloid B72 and glass micro-balloons, looking like a very light white powder; plaster is also traditionally used to fill losses, but glass micro-balloons are lighter and don’t bring any salts to the ceramic. That kind of fill is also reversible and completely neutral towards the ceramic.
Here’s the fill once finished and polished with a heat spatula, ready to be painted.
More fills and building to come in a next post !