A good mucilage for sticking labels on tin is one of the popular wants of the day. Every little while, also, formulas or methods are published, and we should judge from this that many of the methods given are not very satisfactory. We give below some of the most general methods suggested.
The addition of about 3 or 4 per cent. aluminum sulphate (not alum), or, better still, about 10 per cent. of butter of antimony, is said to greatly improve the adhesiveness of the mucilage. Others have suggested roughening the surface with acids in small degree on applying to the tin; thus, honey, flour, treacle, etc., have come into use as seen in formula No. 1.
(1) Make gum tragacanth into a mucilage of the desired consistency with hot water, and then add to it 10 per cent. of flour.
(2) Boil 2 pounds of flour with 1 quart of water to make a stiff paste; add 2 ounces of tartaric acid and 1 pint of molasses. Boil together until stiff and add 10 drops of carbolic acid.
(3) Shellac, 2 parts; borax, 1 part; water, 16 parts, are boiled together until the shellac dissolves.
(4) Add 1 ounce of dammar varnish to 4 ounces of tragacanth paste.
(6) Balsam of fir, 1 part; turpentine, 3 parts. Dissolve. This is only applicable with good qualities of well-sized labels.
(7) Clean the surface by rubbing with a solution of caustic potash and then thoroughly wipe before applying the label. This is employed on the principle of attributing the difficulty to the presence of a thin film of grease, and is also the case with the addition of water of ammonia to the paste.
(8) Brush the surface over with a thin streak of butter of antimony, or with oleate of mercury, clean well, and apply the label.
(9) Brush over with strong tannin solution, allow to dry and apply the label, previously well gummed.
(10) Apply Venice turpentine to good starch paste.
(11) Soften good glue with water and then dissolve in it acetic acid of 10 per cent. strength.
(12) About 15 per cent. of glycerine added to the paste is said to work admirably.