LABELLING BOTTLES Special care is necessary in labelling bottles that are to contain photographic chemicals. First make the outside of the bottle per fectly clean and dry ; use gummed labels, or attach by means of liquid gum, and smooth into close contact. When quite dry, write on the label with ordinary or waterproof ink, or even with pencil, which is more permanent than some inks. Coat, when dry, with size made by dissolving J oz. of common glue in 21 oz. of water, and when this is dry apply a thin coat of oak or hard carriage varnish. A label varnish much used in laboratories, etc., is the following :— Sandarac . . 2- oz. 78 g.
Mastic . . . I „ PP Camphor . • 24 grs. 17 Oil of lavender . 3J drms. 12.25 ccs.
Turpentine . . 2 7 „ Ether . . . 3 10-5 „ Alcohol . . . 2.1- oz. ), Macerate for several weeks, agitating until dissolved.
A less efficient method is to attach the paper label in the usual way, warm it, and smear with wax by rubbing with the end of a candle. Another plan is to coat the attached label with celluloid varnish, made by dissolving celluloid (old films will serve if the gelatine is cleaned off) in acetone, amyl-acetate, or methylated spirit.
The bottle itself may be written upon, using one of the inks given under the heading " Ink for Glass, Porcelain, etc." There are many special recipes for pastes for attaching labels to chemical bottles. Caustic soda and nitric acid are sometimes included with the object of breaking up the starch granules, and alum and sugar to increase the adhesive proper ties. One of the best of the many formula: is :
Wheat flour . . 2 oz. 220 g.
Powdered alum . 160 grs. 37 ,, Cold water . . 10 oz. 1,000 ccs.
Formaline . . 4o drops 8.5 „ Mix the first three ingredients together, boil in an enamelled saucepan, and when cold stir in the formaline.
In America it is common to label flat bottles in the following way. A strip of glass is cut in. narrower than the flat side of the bottle, and the paper label should be about I in. smaller than the glass strip. The written side of the label is pasted to the glass strip, the edges of which are then smoothed. Both bottle and strip are then warmed, and the two attached together with a cement made by melting 1 part of beeswax with 3 parts of resin.
Names may be etched on bottles and the etch ing left plain or filled with Brunswick black or other pigment. Mix up the two following solu tions :—(1) Sodium fluoride, 36 grs. ; potassium sulphate, 7 grs. ; distilled water, 2 oz. (2) Zinc ,chloride, 14 grs. ; hydrochloric acid, 65 drops ; distilled water, i oz. Mix the two solutions and write on the bottles with a quill or camel-hair brush ; leave for about five minutes and then wash off.