Older canvas oil paintings can sometimes need quite a bit of restoration. One of the main steps involved in most restoration processes involves finding and removing mould from the painting. The specific process you use depends on how much mould damage there is. However, if you are careful and use the right cleaning techniques, the mould can be removed and the painting restored.
Put the canvas oil painting in bright sunlight for several hours to dry up any moist mould.
Use a soft-bristled brush to carefully brush away the dried mould. A sawdust brush, for example, should not damage the canvas oil painting.
Fill a spray bottle with water and add several drops of household bleach. You don't need a lot to kill mould.
Mist the canvas oil painting where the mould was located. Also, mist the other side of the canvas right where the mould was on the opposite side.
Allow the canvas oil painting to dry completely. Place it back in the sun to speed up the drying process.
If mould is damp, do not wipe it away. This will damage the oil painting while making the mould problem worse.