THE GLUING OF WOOD 63 
• 
coagulation of the glue and the copper solution, are broken up and until a 
smooth violet-colored glue is obtained. 
Glue prepared by formula No. 11 has proved to be exceptionally strong and 
durable, even under wet or damp conditions. 
CASEIN GLUE FORMULA NO. 4B ** 
Formula No. 11 as above specified but without the copper solution represents 
an earlier stage of casein-glue development, known as formula No. 4B. The 
mixing is the same as for formula No. 11 except for the omission of the copper 
chloride. The glue made by formula No. 4B has a medium consistency, excel- 
lent working properties, a good working life, and makes joints of high strength, 
but it falls somewhat short of formula No. 11 in water-resisting properties, 
especially when the lower amounts of lime are used. 
CASEIN GLUE FORMULA NO. 20 
Ingredients ^ghi 7 
Casein a 100 
Water 200 
Sodium hydroxide (caustic soda) 10 1 
Water 50 
Bring the casein and water together according to the directions for mixing 
glue prepared by formula No. 11. Dissolve the caustic soda in water in a 
separate container, and while the mixing paddle is revolving sprinkle the 
caustic-soda solution into the damp casein. Stir slowly until a thin, smooth 
glue has been obtained. The consistency of the finished product may be altered 
by adding more casein if it is too thin, or by adding water if it is too thick. 
Silicate of soda is sometimes added to thicken or to reduce the cost of the 
glue per unit of volume. 
This glue has exceptional strength when dry, but when exposed to moisture 
it weakens as rapidly as animal or vegetable glue. 
BLOOD-ALBUMIN GLUE— HOT PRESS FORMULA 34 
Ingredients Parts by 
weight 
Blood albumin (90 ; per cent solubility) 100 
Water 170 ' 
Ammonium hydroxide (specific gravity 0.9O) 4 
Hydra ted lime 3 
Water 10 
Pour the larger amount of water over the blood albumin and allow the mix- 
ture to stand undisturbed for an hour or two. Stir the soaked albumin until 
it is in solution and then add the ammonia while the mixture is being stirred 
slowly. Slow stirring is necessary to prevent foamy glue. Combine the 
smaller amount of water and the hydrated lime to form milk of lime. Add the 
milk of lime, and continue to agitate the mixture for a few minutes. Care 
should be exercised in the use of the lime, inasmuch as a small excess will 
cause the mixture to thicken and become a jellylike mass. The glue should be 
of moderate consistency when mixed and should remain suitable for use for 
several hours. The exact proportions of albumin and water may be varied 
as required to produce a glue of greater or less consistency or to suit an 
albumin of different solubility from that specified. 
PARAFQRMALDEHYDE-BLOOD-ALBUMIN GLUE FORMULA 35 
This formula produces a blood-albumin glue, which may be pressed either hot 
or cold. 
Ingredients 
Parts by weight 
Blood albumin (90 per cent solubility) 100 
Water - 140 to 200 
Ammonium hydroxide (specific gravity, 0.90) 5% 
Paraformaldehyde 15 
33 Butterman, S. Op. cit. ^ Henning, S. B. Op. cit. 35 Lindauer, A. C. Op. cit. 
