BEWOED SIZE

119

When European resins are used, the resin should be brought up to a tem-
perature of 140° C. during melting, so that any crystals of a high melting-
point will be melted and dissolved. When the resin is melted the steam is
turned off, and agitation started at the high speed; 9 Ib. of caustic soda in
solution is run in slowly through the y-litre vessel. While this is running
in the casein solution is prepared; 20 litres of water is run into the 130-litre
vessel The steam which is taken to a jet at the bottom of the vessel is turned
on and 12 Ib. of casein tipped in. With the steam still on, i Ib. 2 oz. of caustic
soda in concentrated solution is added, and the solution stirred quickly. The

FIG. 36.-

[Becker and Co,
-BEWOED Mm, SHOTONG STEAM-JACKETED PANS AND MEASURING VESSELS

temperature should not be higher than 82° C, This is diluted to 60 litres at
33P to 43° C., depending on the melting-point of the resin- When mixed, a
further I Ib. 2 02. of caustic soda is added.
When the 9 Ib. caustic solution is all added to the resin, it is necessary to
cool the resin further to 100° C. This can be done with water, or more con-
veniently by using part of the casein solution through the |-inch pipe. The
correct temperature is easily observed by the sudden drop in the amount of
steam given off. If casein solution is used for this cooling, the amount used
must be repkced with water, and the bulk and temperature of the casein solu-
tion brought up to the original figures. This 60 litres of casein solution is
run into the resin through the 2-inch pipe.
A rosin-wax size can also be produced by the Bewoid process* This may