Sono soluzioni con soluti appiccicosi.

Per pulirle bisogna sapere quale era il solvente originale.

You are familiar with paint?

There are two sorts:

1. Like automobile paints and those you give to children which can be washed out with the original solvent. You may find it hard to remove because you are not using the right solvent. Water for some, white spirit for some, acetone for others.
2. House paint and some types of artists paint. With these there is a solvent, a pigment (colour) and a binder. When the solvent evaporates a chemical reaction takes place so that the binder joins the pigment particles together in a plastic sheet. Once fully cured (reaction with oxygen may be involved) the solvent will not dissolve it. Some food and other liquids act like this. As you can often clean your paintbrushes with detergent and warm water, you may be able to clean of the spots this way, before they are fully cured. Mechanical action (rubbing) pulls the particles off the surface and the detergent coats them so they stay in the water.