The invention encompasses a method of forming silicon nitride on a silicon-oxide-comprising material. Here, by the use of the epoxy resin containing the prescribed filler, which can minimize a change in moisture content in an electrochromic film, the moisture content in the electrochromic layer can be stabilized to a level near the use of the sealing glass relative to the environmental changes such as a high temperature and a high humidity. The wrench may also be used as a hand tool, for instance for clamping an object or workpiece for performing work on the object.