It requires good brushes to use linseed paint, and therefore it is important to wash them out after you finish your work. Linseed soap has the advantage that it is a natural product, which means that there is no pigs or other animal remains that have been used to make the soap (unlike brown soap). Therefore it is ideal to use when you are cleaning your brushes, because the oil in the soap dissolves the paint on the brushes. This also means that the soap should not be used on painted woodwork and lacquered wood, as it can cause the paint to peel off.
PLEASE NOTE: The video is in danish but we are working on English subtitles