40 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS even if the Weights and Measures authorities in a manufacturers' area con- sider a method of marking to be within the Act, another officer elsewhere may make a prosecution if he thinks otherwise. It is believed, however, that in most cases of doubt, local officers do refer back to their correspond- ing authority in the manufacturers' area. Mention should also be made of the necessity not to quote misleading wording or to give misrepresentation on outer transit containers or shippers. It is not required to mark these with contents but care should be taken to check that any wording referring to contents is within the Act. As an example, everyone in the trade refers to aerosol containers as 6 oz, 8 oz, etc., but to declare "Contents 200g" on the cans and refer to "8oz size" on the bulk transit shippers is an offence. Where a coffret or carton contains a number of packs it is permitted either to mark the individual packs or to affix a label to the outside of the coffret specifying its contents. If the latter method is employed all items in the coffret must be listed, even if some of them are exempt from the Act as individuals, e.g. on account of their small size. It is only necessary, however, to quote the contents of those items covered by the Act. Calculation of declared quantity It is obvious from the spirit of the Act, and the manner in which it is being operated, that manufacturers should relate the declared contents to a figure which they believe will be met by the pack at all stages of its life. The ambiguity in this area is the meaning of a "mistake or accident beyond his control", always assuming, of course, that he had taken all reasonable precautions and exercised diligence in control. Factors affecting the calcula- tion of quantity are:- (a) the standard fill (b) variation in the size of the container (c) variation in the accuracy of the filling machine (i) by level of fill, or (ii) by quantity dispensed (d) processing loss, e.g. by spray testing, de-aeration, temperature changes, etc. (e) loss on storage after filling and (f) control of all stages of the process. It is normally assumed that the standard fill is a known quantity for any particular combination of pack and product. It is that quantity in a

INFLUENCE OF THE WEIGHTS AND MEASURES ACT ON PACKAGING Jrl mean size container filled to the standard level or the quantity dispensed by a filling machine at its mean setting when working with perfect effic- iency. The variation in the size of the container is quoted in terms of capacity variation by the container supplier, and it is essential that this variation is quoted at the standard filling level. This variation is only important when containers are filled to a level, either by vacuum or pressure. The variation in the accuracy of the filling machine, whether this be in the level of fill, or volumetric quantity dispensed, can sometimes be obtained from the machine supplier. It is, however, best obtained in practice as it may vary slightly with product or the speed of filling. If a plastic container is filled by vacuum, any collapse at the time of filling resulting in a subsequent drop in level when the vacuum is removed, must be taken into account. If the product is filled in two stages, as with aerosols, the variation at each stage must be determined. Any processing loss must be determined or estimated. If a pack is of the dispensing type and it is normal practice to test it after filling, e.g. spray testing of aerosols, plastic squeeze packs or manually operated perfume dispensers, or operation of cream or emulsion dispensers, then the quantity dispensed must be estimated. Any liquid product, subject to aeration, which may de-aerate after filling will decrease its volume and this must be allowed for if the declaration and control are in terms of volume. If, however, both the declaration and control are in terms of weight, this factor can be ignored. A similar calculation will apply to a product filled at an elevated temperature if a volume is the unit of declaration and control. It is impossible to say what loss on storage should be allowed. One cannot over allow, otherwise the declared figure may be too low, but one equally cannot under allow or there may be many packs on the market below the declaration. It is necessary to determine or estimate the anticipa- ted loss of weight or volume from a standard pack, filled and sealed in the standard manner with a correct closure whatever form this may take. The period and condition of this storage loss depend upon the movement of stock, conditions of storage and methods of distribution, but it is safer to estimate for well in excess of the average age at the time of sale under normal storage conditions. I believe that many manufacturers consider two years at 20øC to be a suitable criterion for calculating this loss. It is possible to ignore the higher losses found in packs exported to tropical climates as these packs are exempt, but if this is done then no declaration of contents