Bleaching is a dirty word in conservation, one whispered secretly. However there is no denying that there is something roguishly fun about sticking an old page from a book into a bath of bleach and watching it go from brown to bright white! I can state that the Rev will also be seeing some bleaching treatment in the next couple of weeks, and might then go on the wall!).
This is what we have been doing in the last week with Alan Buchanan, a visiting lecturer of ours, who is very charismatic and great to listen to. We have been working very scientifically and thoroughly, ensuring variables were recorded before starting out, and a control kept.
Preparing the paper for washing
Prior to our various forms of cleaning, it was necessary to record the primary data of the paper, so that we could see the difference once cleaned. We were using pages from the same book, so although they varied slightly in weight, they were very similar on most parts. Each sheet was weighed five times at intervals of 20 seconds, and a mean average taken from those recordings. One sheet was kept as a control and has remained unwashed.
Washing the paper
A simple and straight forward method of cleaning, and one often with satisfactory results as the water will yellow when significant amounts of dirt are removed. Prior to immersion, the page had to be humidified. Immersing a document immediately into water is too much stress for the paper, it needs to be gently introduced to water so that it will accept it more readily. Once humidified we put the page into the water, at about 30 degrees, and left it for 30 minutes. After this, the page came out and was left on the drying rack to dry. In order to flatten it after that, it would need to be humidified again and pressed. Pressing is not something we are doing in our experiments.
In my opinion, this was the method of washing with the most obvious results as a distinctive residue of dirt left on the blotter. Again, prior to the was, we humidified the page. There are a few methods of float washing including ones where the object is left at an angle and water permanently run underneath it, but Alan assured us that there is no evidence to support one method working better than the other, and in his experience, this was an effective one. In a bath containing two sheets of blotter, water is introduced until it reaches the same level as the blotter, no more. Then the humidified object, recto up is placed onto the blotter. We also left this for 30 minutes. The benefit of this method is that the recto is kept dry, or at least away from the water and relatively untouched, which would be important with fragile media. If the document itself was fragile, it could also be placed on bondina before going on the blotter, which would protect it.
The third method of cleaning was the blotter wash, it is an extremely gentle form of washing, should the object have friable media or is delicate in itself. Primarily the first sheet of blotter is lightly wetted, this is a little more needed than for humidification, but not much. At this point both the dry and wet blotter should be weighed. On a clean surface, the dry blotter is placed down, then a sheet of roofing felt (goretex is the more expensive version of the same thing) then the object, recto up, the second sheet of roofing felt, and finally the wet blotter. This should then be covered with a piece of plastic and weighed down to keep the moisture contained. This is then left for an hour or more, as it is a gentle technique and needs time to work. If the object is very delicate, bondina can be used either side of the object. The method works by gravity pulling the water from the wet blotter through to the second, as well as the capillary matting from the roofing felt – this allows vapours through, but not droplets of water. As the second blotter is dry, it will be naturally pulled through to this blotter, via the object, cleaning it in the process. The reason for the object being recto up is so that any matter drawn through the object would show on the verso. Once the hour is up, the blotters are weighed again and there should be a considerable difference in weight.
Washing on the vacuum table
This is not as delicate as the blotter wash, but more so than the other methods. The object must first be humidified before washing to prevent it form being stretched on the vacuum table. The object should be placed on top of a cotton sheet on top of the machine as this will draw the water through quicker and will protect the object. It will also protect the machine from any dirt removed. Once on the table, it can be sprayed gradually all over with water until cleaning is complete.
Localised and differential washing
We were particularly looking at localised washing with additives such as IMS (Industrial Mentholated Spirits) and Synperonic A7 (detergent that reduces surface tension and cleans).
The solutions were made at 100ml quantities as follows:
50ml IMS and 50ml Water
100ml Water and a drop of Synperonic
These were used in conjunction with the vacuum table. The object had to be humidified prior to being washed on the table. The area needing attention was masked out using melinex and the object placed on top of a cotton sheet. Using a very fine brush, the IMS or Symperonic was added directly to areas such as foxing spots, hopefully reducing them, though it was not massively successful. The object should be placed recto up so that anything that is drawn out through the suction, comes out on the verso.