To create the crosshatching effect, we tested several different methods. First, we looked outside our conservation colleagues and went to a company manufacturing high quality laser-cut Perspex blocks to see if they could make a reverse crosshatched mould. Creating such extremely fine detail proved difficult even for the laser cutter and, though the effect was achieved, it was too difficult to produce a good useable mould.
In a second attempt, a positive Perspex block was manufactured so a composition negative could be cast. A mould was taken from the negative to give the background design which was adhered directly to the frame using the traditional method of wetting the back of the mould with hot water. However, this method was extremely time-consuming and keeping the thickness of the cast consistent along the entire length of timber proved difficult.
Further methods were tried and tested with hessian type material and wire mesh applied to a frame sample and coated in gesso then removed just before the gesso dried. However, none of the tests proved too successful in giving the desired effect.
After trying these different methods, the team decided to take a traditional approach and create a frame with a more ‘hand-made’ look. As we had never attempted this before, we carried out a number of tests on small sections of timber to develop the technique and skill required for the cross-hatching design. A Perspex guide, designed in-house and made by Gordon Yeoman at the National Library of Scotland, ensured that all the scores made by hand in the gesso would be at the same angle.