2. Boil the leaves with 10% sodium hydroxide solution. Boil the prepared lye in a stainless steel pot or an iron pot, then add a proper amount of washed leaves and boil. At this time, gently rotate the blades with a glass rod or tweezers to prevent the blades from overlapping and make them evenly heated.
3. Cook for about 5 minutes. After the leaves turn black, take a leaf and put it in a plastic basin filled with clear water. Wash it carefully with clear water.
4. When the residual lye on the leaves is washed clean, take it out, lay the leaves flat on a piece of glass, gently brush off the rotten mesophyll on both sides of the leaves along the vein direction with a small tube brush or a soft-haired old toothbrush, and rinse with small-flow tap water while brushing until only veins are left.
5. Soak the vein in hydrogen peroxide for 24 hours to achieve bleaching effect. Brush the pulse sheet, rinse it, and put it on the glass sheet to dry. Air-dried to a semi-dry and semi-wet state, coated with all kinds of dyes, and then sandwiched in old books and newspapers, and then taken out after absorbing moisture, it can be used as veins bookmarks.