Filling & Labelling Plastic Bottles: Best Practices

Getting filling and labelling right protects your product, prevents leaks and gives your packaging a clean, professional finish. This guide covers the practical steps that matter most for plastic bottles.

Prepare the bottles

Always fill into clean, dry bottles. Even a small amount of dust, moisture or residue can contaminate the contents or stop labels sticking properly. Let rinsed bottles drain and dry fully before you start a run.

Fill and leave headspace

Never fill to the brim. Leave headspace at the top so the liquid can expand with temperature changes and so the cap seats without forcing product past the thread. Headspace also reduces splashing and glugging during filling.

Torque the cap correctly

The single biggest cause of leaks is the wrong cap torque. Too loose and the seal fails in transit; too tight and you distort the neck or crack the closure. Aim for consistent, moderate torque and test a sample from each batch by inverting the sealed bottle. See our caps and closures guide for closure types.

Label adhesion: HDPE vs PET

Surface material affects how well labels stick:

For more on materials, read HDPE vs PET bottles.

Apply labels flat

• Apply to a clean, dry, room-temperature surface
• Keep the label flat and work out air as you go
• On curved or tapered bottles, use a label sized to the flat panel to avoid wrinkles and lifting edges
• Smooth firmly from the centre outwards

Batch and lot marking

Add a clear batch or lot code to every bottle for traceability. Print or over-label it consistently so it stays legible through handling and delivery.

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