MOUNTANTS (Fr., Colles ; Ger., Kleisters) The adhesive by means of which a print is attached to its mount. Of the very many mountants available, starch is by far the most widely used, yet it keeps badly and is unsuitable for glazed prints. A glazed P.O.P. print mounted with plain starch may lose its glaze and show markings, whereas if an alcoholic solution were used the print would be unaffected.
Arrowroot.—This is an excellent mountant when d little gelatine is added :— Bermuda arrowroot 2 oz. 122 g.
Gelatine . . go grs. 11.5 „ Water . . 18 oz. s,000 ccs.
Soak the gelatine in some of the water for an hour or two, and melt by heat. Mix the arrow root into a cream with a little water, and add to the gelatine, stirring all the time. Boil the whole in an enamelled saucepan or in a water bath till a clear jelly forms, and add slowly 2 oz. of methylated spirit and 6 drops of carbolic acid. Allow to cool, and keep as airtight as possible.
Dextrine.—This is a good mountant of a white, creamy character ; it keeps well. A formula is :— Best white dextrine 25 oz. 90o g.
I If 36 „ Sugar4 ,, ,, • • Water . . 3o „ s,000 ccs.
Carbolic acid (so %) 1f „ 54 g• Mix the dextrine with the water, boil for five minutes, add the sugar and the acid, and finally the alum dissolved in about 2 oz. of hot water. The alum may be left out if desired, as it may injure some prints, particularly those on collodio chloride paper. Inferior dextrine is likely tc remain sticky and not dry properly.
Another and a more simple dextrine formula which will meet all requirements is to rub up s lb. of best white dextrine with enough cold water to make a stiff paste and add so oz. of water, and 6o drops of oil of winter-green. Bring the whole to a boil, when it should be like clear gum. Pour into pots or jars, and in about twenty-four hours it should set in the form of a good white creamy paste. Use cold.
Dextrine and Gum.—This has no advantages over dextrine alone. The best formula is :— Gum arabic (best white) f oz. yo g.
Dextrine . 2 „ 355 ,, Liquor ammonia; 2 mins. •5 ccs.
Carbolic acid . 6o ,, Water8 oz. 1,000 „ . .
Powder the gum and mix thoroughly with the dry dextrine, and rub up with 2 oz. of the water to make a smooth paste. Add the re maining 6 oz. of water and boil for ten minutes ; when cool, stir in the ammonia and carbolic acid. This will keep for months.
Gelatine.—Most gelatine mountants have to be heated before use. A standard formula is : Gelatine . . I oz. IIo g.
Glycerine If 50 ccs.
Alcohol . . 1f „ 55o „ Carbolic acid 20 mins.
4 Water (about) 1 oz. soo „ Cover the gelatine with the cold water and allow to soak for twenty hours or more. Pour off any excess of water, place the gelatine in a jar stood in a saucepan, and heat till melted ; then add the glycerine, alcohol and acid with constant stirring. If too stiff, add water.
A liquid gelatine mountant, and one always ready for use, is made by soaking i oz. of gelatine in 3 oz. of water for twenty-four hours, melting by heat, and adding f oz. of chloral hydrate, afterwards heating for half an hour and adding sufficient washing soda to render the gelatine mixture neutral to litmus.
Gum.—Ordinary office and commercial mixtures of gum are likely to cause fading because of the chemicals used to preserve such mixtures. A suitable formula for a photo graphic mountant is : Best gum arabic . 5 oz. 275 g.
Glycerine . . I „ 69 „ Alcohol . . 4 „ 220 „ Water 12-20 „ CCS.
Dissolve the gum in the water, add the glycerine and finally the alcohol.
Indiarubber.—Indiarubber solution (see" India rubber ") is useful for mounting glazed and dried prints without cockling. Cut a piece of paper + in. smaller than the print in both dimensions, place it centrally upon the back of the dry print, coat the exposed margin with the solution, remove the paper, and press the print down on the mount. In course of time, the rubber perishes and the print leaves the mount.