The purpose of priming with lye is to maintain the light colour of floors produced of pine, ask, beech and hevea. If the floor is not primed with lye, it will go darker when exposed to daylight. The lye priming prevents the natural yellowing process of the wood but does not offer any protection against wear and tear. Therefore, after priming with lye the floor must be treated with natural soap or wood floor oil. The floor should not be taken into use before it has been finished with either soap or oil.