Q. I have a 5×9-foot acrylic painting with natural cypress in it (across the middle of the picture). It was caught in about 3 feet of water in Hurricane Katrina. Is there any method I can use at home to clean it? My mother-in-law is the artist, and she said she thinks that warm water with a little soap should take the icky residue off just fine.
A. I am truly sorry for the damage that both your painting and home sustained by the hurricane. While I dont want to add to your anxiety, you need to understand some important issues regarding acrylic paintings. Recently, a conference in London focused on research about the nature and response of acrylic paint films to the effects of cleaning. Acrylics are complex mixtures. A small amount of materials incorporated in manufacturing, to make pigments and the liquids blend together and to guard against freezing, rises to the surface of acrylic paint films. These by-products are easily dissolvable in water. Acrylics take up water in a spongelike way when its introduced to the film. When acrylics are aggressively cleaned, the process can potentially alter the surface appearance of the paint film. The long-term consequence of cleaning acrylics is not fully understood.
Your painting was in long-term contact with dirty water. It took in pollutants from the water and in turn, some of the water-soluble materials in the acrylic film were released into the floodwater. In addition, a piece of cypress that also has water-soluble components appears to have left a stain on the surface of the painting. As with other complex conservation problems, you need to consult the services of a trained professional. I would advise against using warm water and soap to remove the residue and cypress exudates. The paint film could sustain more damage with this type of treatment. A conservator would be able to assess if the residue is removable and what method of dirt removal will leave the film intact. Given the extreme nature of the damage and the materials within your painting, the treatment of this artwork may be very complicated and time-consuming.