CAN WASHING 147 



ing has become defective in spots and that iron is exposed. The 

 exposed iron is chemically acted upon by the acid and some 

 of the other constituents of the cream, causing the formation 

 of metallic salts, which hasten the decomposition of some of the 

 constituents of the cream, either through chemical action, or 

 by accelerating the action bf bacteria, or enzymes, or both, and 

 leading to diverse flavor defects in butter, such as metallic 

 flavor, tallowy flavor, fishy flavor, etc. 



Rusty cans are objectionable also for sanitary reasons. Rust 

 spots present a rough surface, on which remnants of milk and 

 cream lodge readily and from which they are difficult to re- 

 move, and the rust spots harbor and hold moisture to such an 

 extent, that it is very difficult to thoroughly dry the cans by the 

 use of equipment and methods entirely adequate, for the drying 

 of cans free from rust. The tendency of rusty cans to not be 

 perfectly clean and completely dry, causes these cans almost 

 invariably to become foul-smelling, and to pollute the cream 

 and injure the butter made from it. 



Replacing Old Cans by New Ones. An effective means to 

 maintain a satisfactory standard of quality and condition of the 

 cans in use is to adopt a system whereby, at definite intervals,, 

 each month or so, a certain per cent, say one per cent, of the 

 cans, those that are in the poorest condition, is discarded. In 

 this manner there is a constant renewal of cans and at a com- 

 paratively small cost at any one time. 



Retinning Rusty Cans. Some creameries maintain a tin- 

 shop of their own, where defective cans may be repaired and 

 rusty cans retinned. When this can be done at a moderate ex- 

 pense, it is certainly a commendable practice. In many in- 

 stances, however, experience has shown that the cost of re- 

 tinning was out of proportion to the value of the can, and was 

 too great to justify it. 



There are now in operation several outside concerns, who 

 are specializing in repair work of this type and who dismantle 

 old cans, retin the pieces and reassemble them in a manner 

 that the repaired can is practically as good as new, and at a 

 cost somewhat lower than the price of a new can. 



