For bookbinding and repair, the quality of the glue is very important. Flexibility when dry and pH neutrality are both important for long-term preservation. In our conservation lab we use Jade 403, which is a pH-neutral PVA (Polyvinyl Acetate) glue. Jade 403 is available from some art supply stores and bookbinding supply vendors. Other known types of PVA are Sobo and Elmer’s, however these glues are not designed for long term durability and flexibility.