13.—(1) If the intended use is known, caps, lids, gaskets, stoppers and similar sealing articles must be tested by applying them to the containers for which they are intended under conditions of closure corresponding to the normal or foreseeable use and on the assumption that such articles are in contact with a quantity of food filling the container.
(2) The results of any tests carried out under sub-paragraph (1) must be expressed in mg/kg or mg/dm2 as appropriate in accordance with the requirements of regulation 9(2), taking into account the total contact surface of sealing article and container that is potentially in contact with the food.
(3) If the intended use of an article of the type mentioned in sub-paragraph (1) is not known, it must be —
(a)tested separately from the container for which it is intended, with the result being expressed in mg/article; and
(b)the value added, if appropriate, to the quantity migrated from that container.