Never wrap a wet painting in plastic, as this will promote mold growth. Also, the surface may be quite fragile and nothing should come in contact with the surface until it has been thoroughly dried and inspected.
Paintings wrapped in plastic should be removed from the plastic to prevent mold growth if they were in a damp environment, even if there is no overt indication of water damage once they are removed to a safe and dry environment.
If the painting is glazed, the frame should be removed as soon as possible. The microenvironment between the glass or acrylic and the surface of the painting could be very damaging and could lead to sudden mold growth on the surface of the painting, a severe problem that is very difficult to reverse. The glazing will also impede the drying of the painting.
Surfaces (other than art) can be treated with a 10% solution chlorine bleach (one cup of bleach (e.g. Clorox) to one gallon of water).
For mold on the actual artwork, the reverse surface can be lightly misted with 70% alcohol in water. Commercial rubbing alcohol is perfect for this as it normally comes already diluted to 70%. Oddly, pure isopropyl alcohol is not as good as the 70% mixture at killing mold, so, in this case, more is not better. The alcohol and water will desiccate and often kill most active mold. The goal is to just barely dampen the surface. A simple hand-pump sprayer adjusted to a very fine mist is perfect for this. Try to avoid spattering.
If small colonies of mold are growing on the surface of a painting, you can consider lightly dabbing the surface with a cotton swab dampened with the alcohol/water mixture. However, be aware that this is a potent solvent for artist materials and could also damage or alter the paint surface. Testing on an inconspicuous spot first is always a good practice.
When dry, the surface should be vacuumed carefully with a HEPA filtered vacuum. Even when dead, mold can cause potentially dangerous allergic reactions and the HEPA filter will trap the bits of mold from being spewed into the air. It will also trap mold spores so you won’t be spreading them around. Mold on the face of a painting should be removed with a soft brush. Brush the mold up into your vacuum’s nozzle, held just above the surface of the painting.
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