Certain chemical changes in the pigments can be reversed, and the original colour restored. The blackening of _tan_, that orange pigment used by Koriusai and many other artists, can be removed and the original brilliance brought back. The same is true of a certain white that blackens with time. The processes employed are, however, easily capable of misuse; and the few persons who know the methods prefer not to make them public. If a portion of a print is missing, due to a tear or to the ravages of moths, it is legitimate and desirable to tint the paper that is used to fill in the hole so that it matches its surroundings. Water-colours and a fine brush are employed. But on no account should the surface of the print itself be painted; if the colour has worn off in spots, any attempt to restore it will merely increase the damage still further. A very thin print, or one that has been torn in several places, is best treated by pasting on the back of it while damp a dampened sheet of thin, tough Japanese paper. The operation, simple as it sounds, is difficult and requires practice to produce a smooth result. Some collectors paste down the four edges of their prints on thin sheets of cardboard to preserve their flatness. The practice is an undesirable one; it prevents any examination of the back of the print; and does not achieve its end, since the print and the mount expand and contract differently, and wrinkles are almost sure to appear eventually. The better practice is to apply a mere touch of paste to the two upper corners of the print, and affix these lightly to the mount. Over this is then placed a mat, with a hole cut to fit the print exactly, covering and holding down the print's edges, and protecting it from abrasions. The size of the mount and mat is determined by individual taste; 3 or 4 inches margin would seem to be the minimum desirable. After many experiments I have adopted 22½ × 15½ inches as the size for my own collection. Mr. Gookin prefers 25 × 16; but he also finds 23 × 15½ satisfactory if the economy of space is any object. As to thickness, tastes also differ; the mount should be at least thick enough not to bend much with ordinarily careful handling. Heavy Japanese Vellum makes the best mats; it is expensive, but it greatly enhances the appearance of the prints.