112 SWEETENED CONDENSED MILK 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 be done once per week 

 only, 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 



