Storing and preparing preforms
How to receive a batch, where and how to store preforms and what to do before blowing in winter. Below is an interactive checklist for the warehouse and the shop.
Warehouse and shop checklist
Receiving a batch
Storage
Before blowing in winter
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Why storage conditions matter
A preform is a blank that will be heated and stretched several times over. Whatever happened to it in storage shows up in the bottle: dust, condensation, overheating in the sun or deformation in a crushed box.
Sun and heat
In direct sun a box of preforms gets hotter than the air around it. In summer this can bring the material close to its glass transition and affect blowing. Keep boxes in the shade and indoors.
Winter conditioning
Cold preforms heat differently in the blow moulder oven than warm ones, and bottles come out with uneven walls. So in winter the batch rests in the warm shop for at least a day with the boxes closed, so no condensation forms on the cold plastic.
