The conservation of a plan of the Royal Botanic Garden, Edinburgh

There had been some efforts to repair the plan at an earlier date, but these repairs were totally unsympathetic. Nor were they successful as one of the repairs had itself torn.

Continuous rolling and unrolling had no doubt contributed greatly to the damage of what was an increasingly weak structure. The poor condition of the plan posed handling problems for the RGBE. It was difficult to store without causing further damage, and there was no possibility of being able to exhibit it.

Removal of the linen
In order to remove the linen support, the damaged areas of the primary support were held in place with an adhesive (methyl cellulose) and a facing sheet of tissue paper to reduce the likelihood of any further damage when the plan was placed face down.

The plan was then turned over so that the linen was uppermost. The textile was then removed manually as it was found that the linen was sufficiently degraded to simply break up. The underlying adhesive was tested and confirmed as a common starch paste adhesive. The adhesive on the back of the plan was removed manually. The old paper repairs were removed to allow for thorough washing.

The object was then fully relaxed by spraying with a 50:50 solution of IMS and water, then ‘blotter washed’. The plan could have benefitted from further washes, but the support and media are not able to sustain further washing and drying


The plan following the removal of all of the varnish and washing

Lining
Lining was carried out using Japanese tissue and wheat starch paste adhesive to give the support a secondary sympathetic layer and piece together the detached sections. The plan was then repaired. Both lining and repair were carried out using the sintered glass wall board in the Conservation studio.

A layer of Terylene (shirt fabric) was adhered directly onto the glass to act as a release layer and permit the removal of the plan from the wall board once it was dry. A double layered lining was then adhered on top of this, made up of small sheets of handmade Japanese tissue applied at right angles to each other; this lining was to stay on the plan once it was dry. The double lining was necessary to ensure that sprung tears were fully aligned and the object’s heavy weight paper was fully supported. The lining papers were cross grained to avoid a strong grain direction in the linings. The lining paper closest to the object was Tosa Kozo senka-shi (13gsm), and this was applied across the grain direction of the plan. The external lining paper was Kurotani Kizuki kozo-shi (22.5 gsm), and this was applied with the grain direction of the object.

Infill and repair
Infill and repairs along the edges were carried out whilst the plan was on the wall board, using the Japanese tissue Tosa Kozo senka-shi (13gsm) and wheat starch paste adhesive. Any sprung tears or large cracks were then filled in using toasted cellulose powder. Larger areas of loss were filled with pieces of toned Japanese tissue but not fully integrated with the object.

From left to right: detail of area of loss before and after repair.

After repair, the edge of the plan remained uneven, even though the repairs had been attached and now lay flush to the object. It was decided that toning/correcting this edge and creating a finished ‘square’ object would not be suitable for this piece.


From top to bottom, detail of the top edge of the plan before and after treatment.

Presentation
The best option for the long term preservation of the plan was that it remained flat. If the plan was to have been rolled, there was a strong likelihood that the cracks would reopen under such stress. Therefore, the conserved plan was mounted by its edges only onto a rigid support. This ensures that all conservation work is entirely reversible. The rigid support chosen had an aluminium honeycombed centre and a surface skin of glass fibre, making it incredibly lightweight but rigid and very strong. It has the added advantage that it could be mounted very simply into a frame for display. The finished plan was then provided with a custom built case.

The work carried out on the plan took a total of 125 hours.


From left to right: plan before treatment and after treatment.


Follow up
The importance of the plan was not fully understood until after the work was completed. After comparison with other items, it is now believed to be the work of James McNab, who was Curator of the gardens at a time of great change. The inclusion of so many ‘order beds’ charting the different varieties of plants suggests that the plan was used as a teaching aid. Perhaps most interestingly, the plan has helped to explain some of the quirky architecture of the RBGE. A rounded wall at the north east boundary of the garden has been viewed for many years as an oddity. However, the plan revealed that its shape was vital to accommodate a huge willow tree that was obviously regarded with great interest and importance.


Detail of plan before and after treatment, showing willow tree and the boundary wall which was built to accommodate it.