(a) Greaseproof-waterproof fibre pails and tubs for dry or solid or semi-solid articles must conform with the requirements of Item 291, except that the interior of the pail or tub must be lined or so treated as to prevent penetration by the material with which the pail or tub is filled for shipping.
    (b) Side-wall must be constructed of more than one ply not spirally wound, no single ply to be less than .012 inch in thickness, with outer ply waterproofed and all plies firmly glued together;

    Sidewalls may be constructed of fibreboard of single ply meeting the test requirements in paragraph (a) of Item 291, with outer face waterproofed and the ends of fibreboard forming joint or overlap must extend at least two inches beyond beginning of the overlap and must be firmly glued together throughout entire area of overlap and such overlap must be reinforced by metal rivets, staples or stitches not more than six inches apart, or must be fastened by a double row of metal rivets, staples or stitches not more than two inches apart in each row, or secured by a barbed steel strip not less than gauge 22 and not less than one inch wide extending entire length of joint with barbs pressed through fibreboard and clinched on inside.
    (c) Tops and bottoms must be so fastened to sidewalls as to provide a tight seal and withstand ordinary handling and shipping without showing signs of sifting or loss of any contents. When tops and bottoms are made of fibreboard having wooden segments reinforcing circumference not less than 1/2 inch thick, and not less than 1 1/4 inches wide at joint between segments, fibreboard may be not less than same test as shell.
    (d) Drums described in Items 294 and 296 also may be used for transporting semi-solid articles.