Wednesday, 30 September 2015

Conservation of Tracing Paper

Over the past few weeks, I have been working on a collection of architectural plans on tracing paper. These are often in fairly bad condition due to the inherent fragility of the paper. Papers from the 19th and early 20th century were made transparent by either impregnating the paper with oils (such as linseed or poppy), treating them with a strong acid, or by over beating the fibres. These manufacturing processes result in a weak paper sheet that is at high risk of tearing and creasing.
Architectural plan on tracing paper, before treatment. Shows extensive tearing and creasing.
The treatment of tracing paper is complex. Most tracing papers are very sensitive to moisture, which means that traditional paper repair techniques such as using wheat starch paste and strips of Japanese paper are not suitable, as the repair is too damp. Also, due to the transparent nature of the tracing paper, these kind of repairs can be highly visible and distracting.

There are a range of alternative repair techniques available to stabilise tracing paper such as using a heat set tissue with a synthetic adhesive or preparing remoistenable tissues with adhesives such as Klucel G (which uses a solvent to reactivate the adhesive) and isinglass and Japanese paper. I decided against these methods as the heat set tissue tends to not create a strong bond and may fail. I was also cautious of using Klucel G and solvents, due to the effect it may have on the oils in the paper. Isinglass is slightly trickier to handle as it must be kept warm whilst in use, but must not exceed a temperature of 60°C, otherwise its adhesive properties are reduced.

Architectural plan on tracing paper, before treatment.

I wanted a repair technique that I could prepare relatively quickly and would stabilise the tracing paper, without being visible from the recto. I decided to use a bridge repair method that involves taking individual fibres from Japanese tissue and adhering each end across the tear with wheat starch paste. To do this I ripped up a small piece of Japanese paper and soaked it in water. I then drew out individual strands using tweezers and dried them on a glass weight, before cutting them to size with a scalpel. I then adhered these fibres across the tear with a dot of wheat starch paste at each end. I then pressed these locally under Bondina™, blotter and weights and left them to dry.  
Architectural plan on tracing paper, after treatment.
Architectural plan on tracing paper, after treatment. Detail of verso showing bridge repair.
This repair creates a surprisingly strong bond, which quick and easy to carry out while being sympathetic to the material. The plans are now much easy to access and view.

Architectural plan on tracing paper, after treatment. Rehoused in a polyester sleeve.


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