Wednesday, April 1, 2009

The Humidification Chamber

Last week I wrote a post about an archival collection which was recently donated to the Annapolis Heritage Society. We have now had a little bit of time to start digging (not literally but almost) through this material and I am still very excited. There are a about three banker's boxes full of documents which date between 1763 and 1890. The vast majority of these documents were written between 1800 and 1830. The collection includes journals, ledgers, debit slips, letters and various other manuscript documents. This is very exciting since it is a wonderfully detailed chronicle of what was happening in one particular part of the community.

Sadly, some of the documents are in very poor condition. This is not surprising considering that they had been stored in an attic for years. The document at the top, a letter written to Darby Cronin in 1806, is an excellent example. The holes are actually areas where a mouse has chewed on the letter. At the bottom is a dark stain known as a tide mark. These are caused when a section of piece of paper gets wet. By the nature of the paper, the water will start to move through the document. As the water moves, it picks up the surface dirt and brings it along for the ride. When the water dries, it leaves a dark stain or tide mark. On top of these problems, the document has been folded and somewhat crumpled for the better part of the last 200 years.

What do we do with such a document? Is there a way to do this economically? Today's post will show the various steps we go through to clean and flatten such a document. The first step in any conservation work with sheets of paper is to dry clean the document. In the top image we can see a dry cleaning pad. This is essentially a mesh bag filled with powdered eraser (you can also buy loose powdered eraser by the tube). Using small circles, the pad is rubbed over the entire surface of the document. This will remove any loose dirt which could potentially cause stains. When dry cleaning, I am always careful not to rub dirt from one area into an area which has already been cleaned.

The next step is to test the ink to see if it is colourfast. The last thing you want to do is treat your paper and end up with a blank piece of paper at the end because the ink has bled away. Place a very small drop of water on the page and quickly place a piece of blotting paper on top of it to remove the water. If the ink is secure, you will not see anything on the blotting paper. If you see ink on the blotting paper, do not move to the next step. That step is to build a humidification chamber. I'll admit it, I adore the term humidification chamber. It gives me visions of some medieval torture device. In reality, it is a shallow plastic tub with a lid as seen in images 2 and 3. In our case, this is an inexpensive tub from the local hardware store. In image 2 I have placed a small, elevated plastic tray in the bottom of the tub. This tray allows me to keep the document out of the water when it is poured in the bottom of the tub. This is a crucial step since the last thing you want to do is get the document into the water. While I am setting up the chamber, I put a kettle on to boil (if all else fails, I can have a cup of tea). When the water is hot, it is poured into the tub, the document is set on top of the tray and the lid is placed lightly on the tub.

The document only spends a couple of minutes in the humidification chamber. You don't want the paper saturated just relaxed. Almost immediately the paper will curl upward and then start to relax into a flat position on the tray. When it has relaxed, the document is quickly removed and placed between two sheets of blotting paper. The blotting paper will help to remove any moisture on the surface while the paper dries. For the drying itself, the blotting paper sandwich is placed between two sheets of glass as shown in image 4. The glass prevents the documents from curling while they dry. I am using fairly heavy sheets of glass so I have not added any extra weight to the top of the glass. It is critical to make sure that all of the folds are flattened before the document goes under the glass. if they are not, they will be more difficult to remove in future. The documents will now stay under the glass for at least 24 hours.

When I take them out tomorrow, I will use the back of my hand to see if the paper feels cool. If it is cool, it is still damp and should go back under the glass. Image 5 shows some of the documents that I worked on yesterday. As a comparison, these were in similar condition to the document shown in the image at the top of this post. As I move along with this collection, I will try to make posts on some of the other conservation treatments which are needed.

All for now,

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