Packaging foods in glass
Practical Action
Figure 15: Jar sealer
Figure 16: Bottle cooling equipment
Processing
Some products are heat processed after packing into glass containers. They should be heated
and cooled gently in order to avoid breaking the glass. One method of controlled cooling of
containers after processing is shown in Figure (16). Cold water enters at the deep end of the
trough and overflows at the shallow end. Hot bottles are placed in at the shallow end and roll
down to the deep end. The temperature is cool at the deep end and gets hotter along the
trough, so minimising the shock to the hot containers.
Labelling
Paper labels are the most common type used on glass containers. They can be plain paper
that is glued onto the glass or alternatively self-adhesive types. Figure 17 shows a simple
frame which can be used to hold plain labels, wipe glue over top of label in stack, roll jar
along guide rail over label, roll and press jar and label into rubber mat. Small labelling
machines (Figure 18) can be used to apply strips of glue to labels. A typical powered labeller
has an output of about 40 labels per minute.
Figure 17: Labelling table
Figure 18: Small labelling machine
Water soluble glues such as starch or cellulose based glues are best if containers are
returnable, so that labels can be easily removed. However, these glues may loose adhesion in
humid climates. Non water-soluble glues, based on plastic polymers, are available and
advice on the correct type should be sought from the suppliers.
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