Chapter Seven

Treatment Stage 2 – Tape removal

Following the large scale surface cleaning step, the next step – tape removal – seems minor by comparison.
There are two strips of masking tape on the back of one end of the print:

Masking tape on back of The Key

Masking tape on back of The Key

And a temporary repair that was applied when the item first came in to us to stabilise an at-risk area of the print:

Temporary repair strip

Temporary repair strip

All three of these repairs will be removed.
The temporary repair was easily removed just by peeling the tissue away from the print by hand. This is exactly how the Conservation staff would have expected the repair strip to behave. It was a reversible repair with minimal impact on the object.

After removal of temporary repair strip

After removal of temporary repair strip

The masking tape proved to be fairly easy to remove, too. Luckily, the adhesive layer was still sticky and had not become yellow and brittle. This meant that the tape carrier could be removed by warming the adhesive layer with a heated spatula to soften the adhesive and lift the carrier off.

Using a heated spatula to remove masking tape

Using a heated spatula to remove masking tape

Residual adhesive was partially removed by warming the adhesive in contact with a square of blotting paper. The soft texture of the blotter allowed the adhesive to cling to it and be lifted away.

Adhesive residue from masking tape transferred to blotter

Adhesive residue from masking tape transferred to blotter

The remaining adhesive will have to be removed with solvents. The print is too long to fit in the fume hood, but luckily only one end needed to be in there, so with some extra support, The Key turned into The Bridge.

End of print in fume cupboard, for solvent application

End of print in fume hood, for solvent application

The remaining adhesive was removed using small hand rolled cotton swabs dipped in tetrachloroethylene. This solvent is known to work well on sticky masking tape adhesive, and it lived up to its reputation. The adhesive was removed, but as is so often the case with pressure sensitive tapes, some degree of staining was left behind.

Removing adhesive residue with solvent on cotton swab

Removing adhesive residue with solvent on cotton swab

The print is now (temporarily) in a more fragile state as the torn right hand end is no longer held together with masking tape.

Before masking tape removal

Before masking tape removal

 

After masking tape removal

After masking tape removal

This entire area will be stabilised during the repair and lining stage.

Chapter Six

Treatment Stage 1 – Surface Cleaning

It is generally the case that a conservation treatment begins with surface cleaning. Dry particulate matter needs to be removed off the surface of the item so that any treatment steps involving liquids won’t drive that dirt further into the fibres of the paper.

This item, being so large, called for a cleaning technique that could cover broad areas of paper but be very gentle at the same time. The method chosen for the back was crumbed vinyl eraser.

Bag of eraser crumbs

Bag of eraser crumbs

This is worked onto the surface of the print using a gloved hand. The surface dirt sticks to the crumbs and they become discoloured. Once discoloured, the crumbs are brushed away, and fresh crumbs used in their place. This is repeated in a systematic way across the full length and width of the object until it is completely cleaned. Areas of pencil annotation were not cleaned so as to avoid erasing any of the pencil. Ink annotations can be cleaned very gently using this method. As you can see from the images, quite a bit of dirt was removed. Cleaning the back of the print in this manner took around 3 hours.

Working crumbed eraser over the surface of the print

Working crumbed eraser over the surface of the print

 
 
 
Latex gloves after surface cleaning

Latex gloves after surface cleaning

Small areas of more stubborn dirt were cleaned using solid vinyl erasers. This particular eraser is shaped like a pencil to make it easy to hold and use. Plus, it is wrapped in paper to keep the eraser clean, which means no dirt is transferred from the eraser to the object.
These two techniques combined produce a successful outcome.
Localised cleaning before application of vinyl eraser

Localised cleaning before application of vinyl eraser

 
Localised cleaning after application of crumbed eraser

Localised cleaning after application of crumbed eraser

 
Localised cleaning after application of vinyl eraser

Localised cleaning after application of vinyl eraser

The front of the object was a different matter. It is much more damaged and fragile than the back. Cleaning the front was investigated very closely, including microscopic examination, to see if the paper fibres were being disturbed during cleaning.

Cheryl trials surface cleaning using a microscope

Cheryl trials surface cleaning using a microscope

Unfortunately, they were being picked up, so neither crumbed eraser, nor solid vinyl eraser, was gentle enough. A similar print which has been treated in the lab previously was cleaned using a product called Smoke Sponge. This was used at the National Library after their fire in 1985 to clean soot from their books.
Used with a gentle dabbing motion rather than rubbing, the dirt can be picked up off the surface of the print with little impact of the paper fibers.

Cleaning a loose fragment using the smoke sponge

Cleaning a loose fragment using the smoke sponge

 
Smoke sponge after cleaning, showing adhered dirt

Smoke sponge after cleaning, showing adhered dirt

It was surprising how much dirt was removed (although the print didn’t actually look that much better – such is life!)

Again, areas of pencil annotation were avoided, but areas of ink annotation could be cleaned. Edges and tears also have to cleaned very carefully to avoid dislodging loose fibres or fragile edges.
Cleaning the front of the print in this manner took around 4 hours.
So in total, investigating and surface cleaning the print took a couple of days. It is not the sort of work you can do 8 hours straight. You need regular eye and muscle breaks. The work needs to be gentle on the body as well as the print.

Chapter Five

Treatment Proposal

So, having thoroughly gone over The Key from top to bottom, front to back and left to right, now is the time to come up with a treatment proposal to stabilise it.

Conservation treatments don’t try to “restore” the item to its original state. Instead, conservators remove damaging materials and products as much as possible, stabilise the item once that threat is removed and place it into a storage environment where the ongoing deterioration will be slowed right down.

This item is a bit tricky though. As described previously, it was produced using iron salts suspended in gelatine which were developed in acidic chemicals. These acidic chemicals have not only made the paper quite brittle, but they seem to have damaged the residual gelatine as well.

A test was carried out on one of the small loose fragments of the print (about 1cm x 1.5cm). It was washed in deionized water and dried on a blotter.

NAA: A710, 51 - fragment after water wash

NAA: A710, 51 - fragment after water wash, showing brown degradation product washed out

After this simple step the paper actually seemed thinner and softer, which poses the question: did some of the original material wash away (such as the residual gelatine), or did washing the degradation products out of the paper return it to a more flexible state? If it is the first scenario, it is a bad result – we wouldn’t want to remove original material irreversibly from the object. If it is the second scenario, it is a good result, as it has restored some flexibility to the paper, which may not now be as prone to physical damage.

What to do???

As much as we might like to try and wash the print with water to remove acidic degradation products, we run the risk of washing out the image as well, which would further reduce the density of the already faded lines. So, unfortunately, washing the print in water is probably out of the question. 

Could we wash the print in an organic solvent to try and wash some of the degradation product out, but not risk solubilizing the image? A second fragment was washed in ethanol.

NAA: A710, 51 - fragment in ethanol bath

NAA: A710, 51 - fragment in ethanol bath

Unfortunately, nothing was washed out of the fragment, so this procedure wasn’t going to get us anywhere.

Forgetting about “wet” cleaning then, we can turn our attention to “dry” cleaning. The print can be surface cleaned (or “dry” cleaned) with erasers, front and back. This will remove loose surface dirt and brighten up the paper a bit. The front surface will have to be cleaned very carefully to avoid any pencil annotations, and to avoid disturbing the paper fibres which have become brittle and fragile with age.

Remember, too, this item is more than 2.3m long and 0.7m wide, so it is going to take QUITE A WHILE to surface clean it with a regular eraser!

Once the print has been cleaned, the masking tape will be removed so that the tears can be repaired more appropriately and more thoroughly. The full length of the tears will be repaired so that the whole vulnerable area is supported, rather than the current hit and miss approach.

NAA: A710, 51 - old repairs

NAA: A710, 51 - old repairs

The tears will be repaired using a thin tissue paper coated with a starch based adhesive. These are called “remoistenable” tissues and are something we make up in the lab. We make them ourselves so we can control the type of tissue used, the size of the sheet of tissue used and the formulation of the adhesive. The preparation of the tissue and a trial run of using them will be detailed in another blog post.

Once the individual tears have been repaired and allowed to dry, the entire print will be lined using whole sheets of remoistenable tissue. This will give strength to the object, keep it flat and provide a margin around the edges to hinge and mount the print for exhibition

The reason we use remoistenable tissue is so that we can tightly control how much moisture is being introduced to the object during the treatment. Too much moisture could cause the image to bleed, or tide lines to form (these are dark lines that form around small areas that wet out more than the adjacent areas)

NAA: A710, 51 - pre-existing tide lines

NAA: A710, 51 - pre-existing tide lines

After the print has been lined onto tissue, the areas of loss will be in-filled with toned paper. This will serve to reduce the visual impact of the losses making them less distracting to the viewer.

Once the print has been repaired, it will be dried between acid free blotters, paper-makers felts and pressing boards to keep it flat and wrinkle free.

The last stage in the treatment will be to mat and house The Key for safe storage.

Stay tuned to see if it all goes to plan…