Testing pH

Similarly to the recent post on paste, this is another self indulgent post, designed to remind myself of techniques I have used for the future when my brain starts to forget them!

pH is necessary to test on any number of occasions, for any number of reasons. Our recent washing and bleaching session saw us testing the pH of paper before and after doing experiments on the pages of a book. There are are also various methods of testing pH, though I am only looking at the one here at the moment.

Testing pH using a Probe Meter

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Before starting to test the object, the machine must first be calibrated. Once calibrated, it can be used for a day or so, but after leaving for a period of time, it must be calibrated again. The picture shows two pippett jars and two small pots. One jar has an acidic solution with pH of 4, and the second with a neutral pH of 7. A small amount of each solution is put in each small pot and the pippett jars can then be put to one side.

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The probe is kept in an airtight pot with a small amount of deionised water to keep it safe. The next step is to remove the probe and dip it into the pH7 pot. At this point the machine should then be altered so that the dial rests on 7. The probe is then washed with deionised water and dipped in the pH4 pot, again the dial should be moved to meet four.

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This is repeated until the dial no long needs to be moved. The machine should now be calibrated.

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Once calibrated, it is very simple to test the pH. Although one stipulation for this method is that the tested item has to be wet. If testing a dry object, a drop of water can be dropped onto the object and left to soak in. The probe is then rinsed in deionised water and placed on the object, and the reading taken.

Obviously one negative point of this process is that there is the possibility of tidelines, so if it is possible to test whilst humidifying anyway, the risk will be much reduced.

Making Wheat Starch Paste

This is a post I have been meaning to do for a while, both for me to refer to in the future and for anyone interested, and have finally got my act together after a nudge from Sago On Tuesdays! I hope that I may be able to add to it in the future as I learn new techniques. At the moment I only have three or four to list, but they are good ones that I like.

Paste at the V&A

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The V&A use shofu paste powder for their paste, it is one of the most refined pastes and is a good tackiness and consistency. It is also not necessary to let it stand like with common paste, it can be cooked immediately.

– Mix 27g shofu powder to 200ml water in a beaker and stir together
– Place the beaker on a hot plate on a medium heat
– Stir for about 15 mins or until the liquid starts to go clear and thicker
– Turn up the heat and continue to stir until the paste is thick enough and stays on the stirrer.
– Cover the beaker with a damp cloth and place in a sink of cold water to cool
(have a cup of tea)
– Once cool transfer the now jelly like paste to a clean beaker
– Fill with water until the paste is all cover and recover with a damp cloth
– This can now be left for a few days on the side (not fridge)
– When using it, take how much you need and sieve it three times
– Do not return served past to the beaker

In this case and all cases where paste is cooked on a hot plate, the paste must be on the heat for at least 35 mins and constantly stirred. This is so that the enzymes can open up and create the tackiness.

Paste at Camberwell College of Arts

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Paste at Camberwell is unfortunately the slowest process, but very authentic in terms of how it was made once upon a time. It makes quite a sticky dense paste, with little liquid, which is good for many purposes.

– Mix 1 part paste to 4 parts water and leave to stand for 20minutes
– Poor the mix into the top part of a double boiler (above), and fill the lower part with water
– Set to a high heat and constantly stir until mixture becomes like custard
– Lower the heat and continue to stir until it has been cooked for about 35 mins, it should be clear like silicone
– Leave to cool and then sieve 2/3 times

Paste at the The National Arhives

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The National Archives also use shofu paste because of its good qualities, and unlike anywhere else I have been, they also use a saucier, which removes the need of a stirrer! Their paste is also at 20% concentration, which I find a little too liquid, but it is made for everyone, so is what most people there require.

Using a saucier
– Mix 20g of shofu powder with 100/150ml distiller water (dry/wet)
– Put the mixture in the saucier and set to level 4 (out of 5)
– Allow to cook for 30 mins
– Sieve 2/3 times
– Keep in the fridge when not in use

Using a microwave
– Mix 20g of shofu powder with 150ml of water in a beaker
– Microwave at short intervals as below, stirring in the middle
60s/20s/20s
– Sieve 2/3 times

Paper washing and bleaching, vol 1

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.

Weighing the paper
The first four pages, ready for cleaning

Washing the paper
Immersion
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.

Humidification
Ceder humidification chamber
Immersing the page into 30 degrees water
Drying the page on the rack

Float washing
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 second page being float washed
The remaining stained blotter

Blotter Washing
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.

Wetting the blotter
The cleaning method in action

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.

Setting up the table for washing
The object on the vacuum table
Washing the object with a water spray

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.

Washing localised areas

Making Solvent Set Tissue

Today was the final lecture from our visiting tutor who has been teaching us board reattachment. For her final instalment, we looked at solvent set tissue, which is not completely dissimilar to gelatine set tissue, and can also cross over into the heat set tissue theme as well – a multifunctional tool!

The reasons for using solvent set tissue, are twofold, the first being to be used when a book has such sensative leather that to get any paste or anything containing water would cause darkening – this form of paper repair is completely water free and therefore at no threat of causing this. The second key use is speed, as once set up, the process can be much quicker than using paste and tissue. It does have its downfalls as well, which is why it might not be used all the time – it is more permanent than wheat starch paste, if it gets erectly onto the leather rather than the repair tissue, it cannot be removed.

So the technique is as follows:

  • Initially tone some tissue in preparation for it to be pasted onto
  • Get the equipment ready, including a squeegee, a small screen print tray and a water trough to cover them both once used – the adhesive is extremely quick to dry and will not come off once stuck.
  • Humidify the toned tissue.
  • Lay the frame onto a sheet of melinex – this is what the adhesive will end up on.
  • Paste out small batches of adhesive along one edge of the screen and squeegee evenly over the rest of the frame.
  • Once evenly spread, remove the frame and lay out the toned tissue, ensuring a flat surface.
  • Allow to dry.
  • This can then be stored for future use.
  • When using, reactivate with solvent.

The adhesive used is called Lascoux and is an Acrylic glue. It is of the same family as PVA, though unlike PVA, it is completely non-reversable once dried. It is possible to reactivate the adhesive with solvent once dried, though it will not remove it, just make it sticky again. It is this method that is used to reactivate the adhesive on the tissue when you want to use the tissue on a book.

Essays, Letters and Poems 1781, vol 4

Well I’m getting there – I’m not convinced I will finish this book before Christmas given that I’m off next week, but we will see how I do on Thursday and Friday. I’ll need to tone and pair my spine piece and then attach it – bit nerve wracking…

Anyhow – last week was fairly successful – I did in fact manage to attach my boards, using a method of board slotting, as previously planned. First of all, I had to slice through the edge of the board to create a space for the aerocottong to slot into. This was primarily done with a sharp scalpel and then retraced with a cobblers knife to get the width.

The slot made in the edge of the board with scalpel and cobblers knife

Once the board was slotted, the aerocotton on the spine was pasted out and pushed into the hole. Both this and the board slotting create a thicker board edge than would have previously been present, hence it is important to put the book in the press to set well and to the correct thickness. It is primarily nipped for about five minutes, checked for movement, and then left for much longer. I was able to leave mine in the press overnight as I completed it at the end of the day.

Melinex used to protect the text block whilst pasting the aerocotton
The aerocotton slotted into the board edge
In the press

The following day gave me two well attached boards, which was a happy moment! Next I moved onto lifting the edge of the boards in preparations of the leather reback. This was done by first lining the leather with Tengujo 5gsm and Cellugel, to adhere it and prevent the leather darkening. This tissue prevents any loss of friable leather pieces that may have been dislodged during the lifting.

The result - a nice strong attachment
Lifting the edge of the board in preparation for the leather reback

 

 

Joint tacketing

Part of our series of lectures on board attachment included learning and practising joint tacketing. This particular method of reattaching the boards, is not necessarily a popular one as it is quite interventive and requires piercing the spine of the book. Conservators in Oxford have honed their technique and have it down to a fine art, but this is perhaps because they use the method quite regularly.

Another reason for not using this method of attachment that regularly is because it requires a high shoulder to the book, which are often not present. Indeed most of us has to make sample books to work on as our work books from The Courtauld and Lambeth Palace did not have such high shoulders.

One tacket and one piercing point

The technique is to pierce the spine from the inside of the shoulder, either using an awl or a needle screwdriver (which break quite easily), once the hole is made, a hoop of linen thread is inserted into the hole, and looped over itself to be secured in place. Next hole must be put in corresponding areas of the boards to be reattached. At each sewing station, one hole is made on the edge of the board, coming out into two hold on the underside of the board. This way, the two pieces of thread, are passed through the two holes and tied in a knot on the inside of the board, or spread out as in the picture below.

Two threads spread out

It is a very secure method of board attachment, though interventive as mentioned earlier. A way to avoid lifting the hole spine of the book being worked on, it is possible to cut a small ‘L’ along the edge and lift a small piece of the spine to attach the threads.