What does it mean to soak paper in lime water?

When making paper, raw materials should be soaked with lime water, which is called lime soaking water. According to relevant data, limewater is alkaline, mainly to treat some ingredients in raw materials that are not needed for papermaking, so that the ingredients needed for papermaking are looser, so that it is easier to disperse in water to form pulp in the post-treatment process, so the raw materials should be soaked with limewater first for papermaking. Papermaking, one of four great inventions of ancient china, was invented in the Western Han Dynasty and improved in the Eastern Han Dynasty.