Very unstable to moisture you have is a paint based on polyvinyl acetate (PVA). A surface painted with such painteasily washed with a sponge with soapy water.
If the paint is produced based on acrylic resins, it is resistant to water and soap solutions. This paint can be succeeded only mechanically with a spatula, or flap disc on the angle grinder (angular grinding machine). This method is suitable and if necessary clean the large surface. In this embodiment, the suitable belt sander.
Another option is mechanical removal with a wide spatula involves pre-wrapping the cleaned area Newspapers, and as the glue needed to cook the starch paste with the consistency of liquid sour cream. After drying of the paste paint along with the Newspapers to remove easier. Less cheap, but more simple variation of this option involves instead of glue, use Wallpaper glue.
The paint can be removed with chisels. It's a slow and tedious method, but the paint clean the surface can be very efficiently and not producing excessive noise.
With the construction of the dryer section it is possible to rock the place with old color, gradually helping with a spatula. This method is suitable for paints based on acrylic resins.
You can use a special wash on a chemical basis. When the remover is applied on the surface area that needs to be cleaned, it begins to soak into the paint and destroy it. Can be applied with a brush with natural bristles and no plastic parts.
The washes contain harsh substances, organic solvents, acids. Thanks to them, the paint changes its original structure, there is no negative impact on the surface under the paint. Produced such work if possible, ventilate the room. Be careful not to inhale a couple of washes, they are toxic.