Methyl Cellulose is an acid-free adhesive, often used for bookbinding and paper repair. By itself it is a weak adhesive, however, when added to PVA glues, it extend the drying time , allows the glue to be spread easier. By extending the drying time it also enables repositioning of the glued paper or bookcloth. Comes in powder a form. Mix one pint warm water (or room temperature) to 1 or 2 tablespoons of powder, depending on desired viscosity. After mixing with water, this product has a 6 month shelf life as long as it's kept in a covered container.