Paper and Printing Recipes / A Handy Volume of Practical Recipes, Concerning the Every-Day Business of Stationers, Printers, Binders, and the Kindred Trades

by John Sawtelle Ford

To Make Glue Waterproof.

The best substance is bichromate of potash. Add about one part of it, first dissolved in water, to every thirty or forty parts of glue; but you must keep the mixture in the dark, as light makes it insoluble. When you have glued your substances together, expose the joint to the light, and every part of the glue thus exposed will become insoluble, and therefore waterproof. If the substances glued together are translucent like paper, all will become waterproof; if opaque like wood, only the exposed edges will become so, but they also protect the interior—not exposed parts—against the penetration of moisture.