112 SWEETENED CoNDENSED Mi1,K—SEALING 
hand. Machines of this type will fill from twenty-five thousand 
to thirty thousand cans per day (ten hours). 
These machines are of complex construction and must re- 
ceive proper care. It is best to clean them thoroughly after each 
day’s work. But, since their inlet and discharge are closed her- 
metically, the complete washing may he done once per week 
enly, without seriously disturbing their efficiency or impairing 
the product. For thorough cleaning, the filler should be dis- 
sected, removing all detachable parts, such as valves, pistons, 
tubes, etc. When freed from all remnants of condensed milk, 
the parts should be scalded, dried and replaced in the machine. 
In order to guard against all possible contamination by remnants 
of wash water, it is advisable to reject the first few cans of milk 
of the next filling. When not in use, the filling machine should 
be covered with clean cloth, or oil cloth, to protect it from dust 
and flies, etc. 
‘ 
As soon as the cans are filled, they should be “capped.” If 
allowed to stand open, dust, dirt and flies, or other insects are 
prone to reach their interior, and the prolonged exposure of the 
condensed milk to the air and light causes the surface to crust 
over and to develop a tallowy flavor. 
SEALING. 
Kinds of Seals——The seal must be air-tight and firm enough 
to prevent its breaking during the rough treatment to which the 
cans are exposed in transportation. There are several methods 
of sealing the cans, depending largely on the construction of the 
can. Most of the cans used are sealed with solder. There is a 
groove, around the opening, the periphery of the cap fits into this 
groove and the latter is filled with solder. In the case of cans 
which are sealed without solder, the cap or the entire end of the 
can is crimped onto the can so as to make a hermetical seal. The 
McDonald seal with the friction cap, the Gebee seal with the burr 
cap, and the Sanitary can seal with the top of the can crimped on 
after filling, are the chief types of solderless seals. In the case of 
the McDonald seal, a tightly fitting cap with a wide flange is 
pressed into the opening. ‘The “capped’’ can passes under a 
series of steel rollers pressing the flange firmly against the top of 
