Contamination of many surfaces with water, soot, smoke, tannins and tobacco can result in color coming through the paint surface to cause stains. Stains caused by water will leave a tide mark and after drying, the paint around the stain can be removed and the surface repainted. If the surface may become damp again, remove the source of the water or paint with chlorinated rubber or a hard varnish. Patches of soot or smoke should be removed before coating. Use of an insulating paint before the final coat can help. Nicotine should be removed with an alkaline cleaner (bleach) before coating. Remember to wash off all the alkali before attempting to paint.
some ingredients, notably antidegradants, will not only bloom to the surface of a rubber article, they will migrate to contacting surfaces and at times make a visible stain that may be objectionable