Chapter Nine

Repair tests

Our poor sacrificial item has been torn up and punctured through, to replicate the types of damage to be repaired on The Key.

Applied puncture

Applied puncture

 

Applied tear with overlapping sections

Applied tear with overlapping sections

As mentioned in our last post, several repair techniques were trialled which involved mimimal use of water, to avoid causing tide lines in the areas of severe discolouration.
The first technique was a traditional one, using wheat starch paste made with water and applied to a thin hand-made Japanese tissue. The tissue was pasted out onto blotter before applying it to the item, to absorb as much water out of it as possible, but it still wasn’t dry enough, and a faint tideline did form on one end of the repair:

Starch on tissue repair, with tideline circled

Starch on tissue repair, with tideline circled

Test number two used a modified cellulose adhesive (called Ethulose) dissolved in ethanol applied to the same hand-made Japanese tissue. It looked promising, but the adhesive bond proved too weak for this application:

Modified cellulose adhesive in ethanol, on Japanese tissue

Modified cellulose adhesive in ethanol, on Japanese tissue

The third test trialled a patch made from remoistenable Japanese tissue. The tissue had a mixture of starch paste and methyl cellulose (both made with water) applied to it, which was allowed to dry; the paper was then torn to the right size and shape for the repair. The adhesive was re-activated with a very light application of moisture from an artists’ brush. This technique worked well, providing a strong bond with an unobtrusive tissue patch, and did not cause tidelines:

Remoistenable water-based adhesive on Japanese tissue

Remoistenable water-based adhesive on Japanese tissue

A remoistenable repair using the ethanol-based adhesive was not trialled due to the weak nature of the adhesive evident from the second test described above.

The fourth and final test used BEVA 371 film on a very thin Japanese tissue called Tengujo. BEVA film comes in a roll on release papers, and firstly it was applied to the Tengujo using a heated spatula set to 70°C. This was then cut to shape and applied to the tear with the same heated spatula. The technique was highly successful as it provided a strong bond and an even less obvious patch than the remoistenable adhesive. The patches applied were very small but effective, which suggested they would be useful as sutures (small repair strips applied along a tear at intervals):

BEVA suture in place on tear

BEVA suture in place on tear

 

BEVA patch in place on puncture

BEVA patch in place on puncture

After evaluating all the test results, the course of action I am choosing to take is to use small sutures of BEVA film on Tengujo tissue to hold the tears in place where the overlaps change direction:

Incorrectly overlapped tear

Incorrectly overlapped tear

 

Correctly overlapped tear

Correctly overlapped tear

The suturing will be done from the front, to ensure all the tears are correctly aligned, then the whole item will be turned over and each tear repaired along its entire length.

Chapter Eight

The sacrifices we make

I have thought long and hard about what would be the best approach to take to repair the tears in The Key. My initial thought was to use a remoistenable lining paper, but there are two problems with repairing it in this manner:

  1. The yellow discolouration throughout the print is water soluble, which means that if an aqueous adhesive is applied to it, the yellow discolouration may move with moisture and dry with a dark ring around the edge of the area (known as “tide lines”). This is very likely to happen as there are lots of areas on the print where it has already occurred (refer to blog Chapter Five); and,
     
  2. There are faint annotations on the back of the print, which means that an overall lining of the print will cover these and make them almost impossible to read, and a partial lining would look cumbersome and mean some areas are supported while other areas are not.

To test various repair techniques and decide on the best one, a sacrificial item was sourced at an op-shop:

Sacrificial trial object - front view

Sacrificial trial object - front view

This item has extensive yellow discolouration and iron gall ink annotations, and is brittle and easily damaged, just like The Key.  I found that the yellow discolouration moves on the trial object just as it does on The Key, so the potential for forming tide lines on The Key can be accurately replicated.

Trial object: application of water to yellow discolouration

Trial object: application of water to yellow discolouration

 

Trial object: tide line formed

Trial object: tide line formed

Different repair techniques will be trialled on this object to ensure a technique can be developed which does not cause movement of the yellow discolouration. This will mean that the tears on The Key can be stabilized individually rather than lining the entire back surface, therefore allowing the annotations on the back to remain visible.

The repair techniques to be trialled include:

  1. Traditional repair with wheat starch paste and hand-made Japanese tissue
  2. Traditional repair with solvent based adhesive like a modified cellulose and hand-made Japanese tissue
  3. An aqueous (water-based) remoistenable tissue patch
  4. A non-aqueous remoistenable tissue patch
  5. A low temperature heat activated adhesive like BEVA 371 on tissue
  6. Small “sutures” made from Japanese tissue adhered with wheat starch paste
  7. Small “sutures” made from Japanese tissue adhered with a non-aqueous modified cellulose adhesive.

All of these techniques will introduce the smallest amount of moisture possible and also cause the least amount of cockling along the interface between the adhered and non-adhered areas. The technique deemed the most successful on the trial object will be put into place on The Key.