(a) Containers shall be cleaned thoroughly immediately before filling, and precaution must be taken to avoid soiling the inner surfaces subsequently.

(b) The inside surfaces of containers of metal, glass, or other material shall be washed by spraying in an inverted position with running water at a temperature of at least 180 °F. The container washing equipment shall be provided with a thermometer to register the temperature of the water used for cleaning the containers.

(c) Perfect closure is required for hermetically sealed containers. Heat processing shall follow promptly after closing.

(d) Careful inspection shall be made of the containers by competent plant employees immediately after closing, and containers which are defectively filled or defectively closed, or which show inadequate vacuum, shall not be further processed until the defect has been corrected. The containers shall again be inspected by plant employees when they have cooled sufficiently for handling after processing by heating. The contents of defective containers shall be condemned unless correction of the defect is accomplished within six hours following the sealing of the containers or completion of the heat processing, as the case may be, except that (1) if the defective condition is discovered during an afternoon run the cans of product may be held in coolers at a temperature not exceeding 38 °F. under conditions that will promptly and effectively chill them until the following day when the defect may be corrected; and (2) short vacuum or overstuffed cans of products which have not been handled in accordance with the above may be incubated as provided in paragraph (i) of this section in the inspected plant under Program supervision, after which the cans shall be opened and the sound products passed.

(e) Canned products shall not be passed unless, after cooling to atmospheric temperature, they show the external characteristic of sound cans; that is, the cans shall not be overfilled, the ends of the cans shall be concave, there shall be no bulging of the cans, the sides and ends of the cans shall conform to the products, and there shall be no slack or loose tin in the cans.

(f) All canned products shall be plainly and permanently marked on the containers by code or otherwise with the identity of the contents and date of canning. The code used and its meaning shall be on record in the office of the circuit supervisor before use.

(g) The canned products must be processed at such temperature and for such period of time as will assure keeping without refrigeration under usual conditions of storage and transportation as evidenced by the incubation test.

(h) Lots of canned products shall be identified during their handling preparatory to and during heat processing by tagging the baskets or cages in which the cans are being conveyed, with a tag which will change color on going through the heat processing or by other effective means so as to insure the proper channeling of the products for effective heat processing after closing the cans.

(i) Facilities shall be provided to incubate at least representative samples of the fully processed canned products. The incubation shall consist of holding the canned products for at least 10 days at about 98 °F. The extent to which incubation tests shall be required by inspectors depends on conditions such as the record of the inspected plant in conducting canning operations, the extent to which the plant furnishes competent supervision and inspection in connection with the canning operations, the character of the equipment used, and the degree to which such equipment is maintained at maximum efficiency. Such factors shall be considered by the circuit supervisor in determining the extent of incubation testing at a particular plant. In the event of failure by an inspected plant to provide suitable facilities for incubation of test samples, the circuit supervisor may require holding of the entire lot under such conditions and for such period of time as may, in his discretion, be necessary to establish the stability of the canned products. The circuit supervisor may permit lots of canned certified products to be shipped from the inspected plant prior to completion of sample incubation when he has no reason to suspect unsoundness in the particular lots, and under circumstances which will assure the return of the products to the plant for inspection should such action be indicated by the incubation results.