Much ado about waterstains
In conservation, the removal of water stains is a challenging problem.
Often this is done for aesthetical reasons. The stains in themselves are usually not harmful to the canvas structure and paint layer. In the case of the Fredrikshald Theater scenery, there is a visually disturbing line of stains in the middle of the backdrop. These stains are caused by the leakage of water onto the canvas while it was rolled up, resulting in a vertical pattern of stains. The discolouration and tidelines take attention away from the scenery as a whole. The borders also suffer from disturbing stains in the middle of the light blue sky. Since every stain reacts differently to treatment, we tried a variety of materials to find the most effective and least harmful method. The paint layer in both backdrop and border is water soluble, so we needed to consider treatments that don’t soak the canvas too much.
In the backdrop we used concentrated Methocell A4C gel applied by brush through Japanese paper. The idea is that the gel and the tissue limit the amount of water that comes in contact with the painted canvas. In addition, the Japanese paper will absorb dirt and soiling from the water damage. The borders of the stains were sharp with concentrated dirt to begin with, and this method softens their outline. To remove them completely is difficult as the stains are rather old, and more invasive and tougher treatments could affect the paint layer adversely.
In the borders the stains are reacting quite differently, and a variety of methods have been tried. Initially, Sepiolite a white clay was tested in combination with ethanol. The Sepiolite acts like a face mask, and the theory is that the clay will extract the dirt from the painted surface. However, this method was only partly successful, and we decided to do something more similar to the backdrop group with Methocell in a gel form, in combination with a mixture of water and ethanol.
The results of the removal of these trials is not quite satisfactory and further tests will be undertaken.