Another formula is : Starch, 2 ounces ; white glue, r ounce ; acetic acid, ounce, and a i few drops of oil of cloves. The glue is first soaked in cold water, melted, and boiled, and while boiling the starch mixed with cold water is added.
Arrowroot following has been given as a good recipe : Best Bermuda arrowroot 3} ounces Gelatine (Nelson's No. 1) 16o grains Methylated spirits . 2 ounces Carbolic acid (pure) 12 minims Water (cold).... 30 ounces Mix the arrowroot into a stiff cream with a portion of the water, while the gelatine is placed to soak in the remainder. When the gelatine is softened, and the arrowroot well mixed, pour all together into an iron saucepan and bring to the boiling point. Keep at this heat for about five minutes, being particularly careful to stir continually from the moment the mixture is placed on the fire. When sufficiently cooked, pour into a basin to cool. When cool, add the carbolic acid and spirit (previously mixed) in a thin stream with constant stirring ; then bottle, and keep well corked.
Albumen has been recommended as a mounting medium. The method of preparing a solution will be found given in the directions for preparing albumenized paper.
Gum is a very adhesive medium. A pale-colored gum arabic is used. Take about four ounces, and dissolve it in about eight ounces of distilled water. If the gum has a dirty appearance it should be previously washed in a little cold water to remove all impurities. When dissolved in the distilled water it can be kept in well-filled bottles tightly corked. If required to be kept for any length of time the addition of a small quantity of salicylic acid will act as a preservative. It will then keep for fourteen or fifteen days. If hot water be used to dissolve quickly its keep ing properties are considerably lessened.
Dextrine Mountant.—Formula : White dextrine (pure) t ounce Boiling distilled water 3 ounces Methylated spirit ounce Pour the boiling water on the dextrine and dissolve. Then add the spirit, and strain through fine muslin or calico.
Solution has been often recommended as a mountant, the only drawback to its employment is its liability to become dry and crumbly, causing the picture to leave its support.
The method of its production is to dissolve pure masticated rubber in about forty times its weight of chloroform or benzole.
Gelatine and Alcohol is a very favorite one with amateurs, owing to its simplicity and cleanliness. The method of preparing it is to soak about one ounce of gelatine in ten ounces of water. When it is thoroughly swollen it is melted by gradual heat in a water vessel, and about four ounces of methylated alcohol slowly added, well stirring the solution during the addition. If required to be kept for any length of time, a few drops of a carbolic acid solution must be added as a preservative.
r1OUNTING.—The operation of adhering the print to a suitable support. Although photo graphs may be attached to wood, glass, or many other substances, cardboard is the one generally used. The art of mounting only comes by practice. The materials that are required are a suitable cardboard mount and a good mountant. Under the respective headings will be found some information with regard to the selection of these. The prints are first trimmed to size. It is important that they be cut evenly and in proper proportion, as nothing has a worse appearance than a badly cut picture. The mount employed should be of a color and size to suit the picture with regard to its dimensions, to allow of a sufficient margin. The back of the print having been brushed over with the mountant, it is laid very carefully on to the mount, exactly in the center. It is then pressed gently down into perfect even contact with a soft handkerchief, or rolled with a print roller specially devised for the purpose (see Fig. 292), and afterwards rolled or Gelatino-chloride prints which have been glazed by the talced glass process are much more difficult to mount than ordinary albumenized prints. The following remarks by the author* may be found useful.
Gelatine is peculiarly susceptible to moisture, and this, in the case of gelatine prints, where the surface has a high polish, is plainly seen. If we take a piece of dampened paper and lay our glossy print upon it, face upwards, we shall see that this gloss gradually fades away until the surface of the print has become quite dull.