PETpla.net Insider 03 / 2014

BOTTLE MAKING 34 PET planet insider Vol. 15 No. 03/14 www.petpla.net Laboratory tests on sample bottles – Bottles, preforms and closures, part 9 Mould trials and examination of sample bottles Normally the finalised mould design is used to make a single cavity for the production of sample bottles in a labo- ratory machine. These sample bottles are then tested comprehensively to see whether they meet the defined requirements. This article will cover the next steps in bottle examination from strass cracking resistance to segment weight distribution. PETplanet insider is publishing extracts from successive chapters of Ottmar Brandau’s “Bottles, Preforms and Clo- sures”, which was first published by hbmedia. A newly revised version is reissued under the Elsevier imprint. Stress cracking resistance Failure in the base area under the influence of alkaline solutions (stress cracking resistance) is espe- cially important for bottles intended for carbonated products. Although today many conveyor systems are lubricated with acid lubricants, this test is still demanded by a number of customers. The bottles are tested in freshly blown condition and/or after a defined ageing period. The test bottles are pressurized at up to 5.3 bar by either filling them with carbonated water or connecting them to compressed air hoses. They are then placed in separate dishes with diluted soda lye. The criterion for the