These areas should be scraped most aggressively until clean wood is revealed. Once the inside is cleaned and scraped the saya must be reasembled with rice glue. To make the glue take a small quantity of Japanese rice and cook by boiling until edible. Cover for a couple of days in a small container to reduce moisure loss and allow to sit. After sitting for two days work it into a paste with a bamboo spatula.
Distilled water is added to achieve the correct consistancy.
When all lumps have been eliminated and the texture is smooth, it can be further refined by pressing through a layer of clean white cotton. Gather together the edges and twist until the glue is extruded in beads through the fabric. Dab the joint surfaces with glue until they are covered but do not get glue into the interior. Do not over glue as the excess will be squeezed into the blade cavity. Bind both sides of the saya together with tape or cord and allow to cure for one week.