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Treatment
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17 Jun 2005
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10753/1-3, 10756/11-13, 10760/9-10, 10754/12, 10763/6
Remove gelatin that is actively degrading if possible. Where gelatin can be removed, the fragments will be relined: photographs before each stage are necessary therefore. Consider using microchamber paper to halt further deterioration.
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Western Art on Paper
- Reason
- Storage
- Description
- This frame and the other 9 frames noted on the requisition were treated as a group as they all had been noted as having very deteriorated gelatin. It was possible to remove the gelatin from the papyrus fragments in 3 of the frames (10753/1-3), but the extreme difficulty in doing this called for the treatment of the remaining 7 frames to be re-assessed. Additionally the fragments inside most of these frames, unlike those in 10753, had been attached with cellulose nitrate adhesive. Experience of removing such fragments by previous conservators had shown the treatment to very difficult and only partially successful (10752/2 and 3).
This was discussed with the curator. It was thought that if a method could be found to establish whether or not active deterioration was still taking place this would direct any further course of action. If the gelatin was no longer deteriorating the papyri could be left in storage and checked periodically. If this was not the case and the gelatin was still slowly deteriorating further, another course of action such as placing the frame in an anoxic environment, would have to be considered.
A request was made to the Conservation Science section to see if a method for establishing whether deterioration was ongoing could be found. The subsequent report (AR2005/13) recommended that the degraded areas be mapped (traced) and the frames monitored.
The deteriorated areas were then traced but it was found that this cannot be done with accuracy because the real extent of the deterioration can only be noted in certain lights. In order to see this clearly the frames have to be held at an angle and tracing is not then physically possible. For this reason the frames were photographed also. The exact set-up is recorded here for future monitoring:
Frames raised 3 cms away from black card background using formica slats each end of the frame;
Photograph lights in WAP studio lowered so that light passes both above and below the frame;
F stop 5.6, one-thirtieth of a second, used with camera hand held at an angle that highlights all the deteriorated areas of the gelatin including the spots or rings which appear on some.
A test which could be carried out in the studio using A-D strips was then undertaken. These strips are designed for monitoring photographic acetate film and will indicate the presence of acetic acid by changing the colour of the strip when enclosed for 24 hours with the suspect material. These tests are limited and are not quantative but the off-gassing of acetic acid is a good indicator that some chemical activity is taking place.
Firstly small pieces of gelatin which had been removed and bagged from the papyri in frames 10753/1-3 were tested. The indicator strips are a strong blue colour which will change from blue to blue-green to green-yellow according to the amount of acetic acid present. No change in the colour indicates that there is none present. The strips showed no colour change after enclosure with the gelatin from the 10753 frames. New gelatin film was also tested and here there was also no change.
Three frames were then tested, chosen as representative were:
10754/12 which has a number of 'rings' noted on the gelatin
10756/11 this series is very deteriorated and cellulose nitrate adhesive is visible on the film, frames 12 and 13 have very friable fragments inside and so 11 was opened
10763/6 has one edge quite dard and cockled but otherwise the film is reasonably clear
The frames were opened and the A-D strips were placed in contact with the gelatin film, but not the papyrus, in the most deteriorated areas. They were then covered and left in the dark for 24 hours. Results were good, showing only a small colour change in the strips placed inside 10754/12 and 10756/11. There was no change in the strips placed in 10763/6. The frames and strips were photographed.
The A-D strips were removed from the frames and examined further. Although minimal, there was a definite change of colour, towards green, on the edges of the strips placed in 10756/11 and 10754/12. It was decided to put some microchamber paper along the inside edges of the glass mounts of these two frames. This paper is a pure paper containing a combination of molecular sieves and alkaline buffers to trap and neutralise the by-products of deterioration (such as acidic gasses from the gelatin) and also airborn pollutants (pollution entering the frame from outside). If further deterioration is taking place in these frames it is hoped that this will inhibit all or part of it. Therefore 2 layers of 4mm strips of Microchamber Micro-leaf Endpaper 130 gsm (supplier Conservation Resources) were pasted along each of the four glass edges before the mounts were resealed. As previously with 10756/11 and 10754/12 the old buckram binding was left in place and the frames were sealed with 3M scotch Magic tape no. 810 over the original binding.
There is yet a possibility that Conservation Science can use a probe to detect gasses inside the frames . In this case frames 10756/12 and 13 or 10760/9 and 10 would be suitable candidates as they are very deteriorated, contains cellulose nitrate adhesive and their particular friability make it undesirable to open the frames.
At present the recommendations of monitoring will be followed. In previous years photographic monitoring had proved of limited use because of the difficulty of taking photographs with consistent lighting conditions. For this reason the present method used was with lighting and angle which shows the whole extent of the deterioration not visible when looking at the papyri straight on with the naked eye, or even on a dark background using a copystand. The latter was the method used in 1992 when the papyri were photographed for monitoring (not 10754/12) and which at least show no change to the papyri seen in normal light. Monitoring, by comparison with photographs and tracings, will take place in three months time, September 2005 and thereafter at longer periods if no changes are observed.
In January 2006 photographs of the deteriorated areas were taken through the Leica microscope, x 30, for accurate future monitoring.
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- Treatment