It is always preferred to use dedicated plain PVC/PVDC foils for specific product blister packing. This is because it may not be possible to clean the foils to eliminate cross-contamination due to different products.
In general, the primary packaging materials must be well protected from environmental contamination and product cross-contamination by wrapping them to foil rolls with double polythene bags during their storage and transfer from the warehouse to the packaging lines. Even when the unused foil roll is returned from packaging lines to the warehouse it must be properly covered by double polythene bags. Also, it is to be ensured that when the foil rolls are received from the suppliers they are well protected.
When transferring the foil roll from the warehouse to the packaging line, the outermost polythene bag should be removed in the air-lock between blister-packing machine room and the packaging corridor. This is to eliminate contaminants like dust, and dirt accumulated on the outer polythene bag of foil roll before it is transferred to blister packing room.
Examination of cleanliness of primary packaging material depends upon its type, such as bottles, containers, foils, sachets etc. Inhouse methods should be developed for this purpose.