A Technical Guide
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Good labelling practices

Rowan A Beattie, Managing Director, Pyrotec

Introduction

In order to optimise productivity of the self-adhesive (pressure sensitive) labelling operation, the following practices must be adhered to at all times.

Handling and Storage

  1. Scoring of or moisture on the edges of label reels must be avoided as nicks to or weakness of the backing paper edges will cause web breakages on the production line. On receipt handle the reels with care. Do not drop.
    • Place the packets and/or reels onto pallets or shelves. These pallets or shelves to have solid wood surfaces or to be covered with smooth cardboard.
    • Do not cut the outer plastic wrapping with a sharp object. This can damage the edges of the backing paper.
    • Pick up reels of labels by hand, not by using a hard or sharp object e.g. screw driver, fork lift truck, etc. Sharp objects can cause damage to the edges of the backing paper.
  2. Self-adhesive labels should be stored at between 15°C and 25°C at 55% RH, away from direct sunlight and in their original packing and not on the floor.
  3. Always store reels of labels on the flat sides of the roll. Storing on the circumference can put pressure on the label face and could elongate the inner core.
  4. Label reels issued to production must be stored on smooth surfaces as in (1) above.
  5. Have a rodent and pest control policy in place. The edges of labels can be chewed by rats etc.
  6. Shelf life of labels is normally 12 months from receipt, when stored in the correct conditions.
  7. Do not store reels of labels higher than 500 mm and place thin cardboard between reels.
  8. Ensure a practice of FIRST IN – FIRST OUT so labels are not stored beyond their shelf life.
Production

To ensure trouble free labelling, the following factors are important:

  1. Presentation of bottles to the labelling beak must be consistent. If bottles are not presented in the same plane every time, inconsistency of label positioning will result.
  2. The bottle surface to be labelled must not be contaminated with moisture, condensation, dust, silicon release agent, varnish, grease, etc. The presence of any of these elements will result in the adhesive not being able to adhere to a stable surface. Bottle temperature should ideally be above 13°C when labels are applied.
  3. The surface to be labelled must be smooth (i.e. free of ridges). Ridges, stipples and imperfections will prevent 100% of the adhesive being in contact with the surface and could result in label lift.
  4. The labelling head must be mounted in such a way as to avoid vibration. Vibration will result in inconsistent label positioning.
  5. The label reel must be firmly wound; having tension applied at all times to enable ease of dispensing of the label. A slack web will result in the labels following the web around the beak and not releasing from the backing.
  6. Product and label microswitches and/or sensors must be clean and free of paper dust and lint.
  7. The leading edge of dispensing beak must be 1mm in diameter, smooth (no nicks) and clean.
  8. Guide rollers and dispensing beaks must be kept clean of paper dust, adhesive and other foreign matter which could ‘snag’ the edges of the backing paper.
  9. Sufficient pressure must be applied when wiping down the labels to the bottle to maximise adhesive flow.
  10. Adhesion of the label to the container surface increases from application to 24 hours after application when ultimate adhesion takes place. Depending upon the label material, adhesive type and container surface, the label may be removable shortly after application.
  11. After ultimate adhesion of the label to the container, should the label or adhesive and residue need to be removed, use toluene.

PROBLEM POSSIBLE SOLUTION
Label does not adhere to the surface
  • check for surface contamination
  • test contamination by cleaning
  • surface with ethyl acetate
  • check surface is smooth and free of ridges
  • check the label is being dispensed at the same speed as the bottle is travelling
  • ensure label wipe down pressure is sufficient and covers the complete label
  • ensure adhesive for the specific application is suitable
  • ensure the caliper/rigidity of the label paper is suited to the bottle diameter
Web breaks
  • check for nicks on the edges of the web
  • ensure web guides are clean, free of adhesive and paper dust
  • check labelling beak is smooth
  • check web for too deep die cutting
Labels do not dispense or dispence erratically
  • ensure label reel and web is consistently taught/firm.
  • check forward movement of web is consistent
  • (does not jerk)
  • ensure the labelling beak edge has a diameter of 1 mm or less and round
  • check for ease of label removal from the backing paper
Label placement is inconsistent
  • gap between labels must be consistent
  • presentation of the bottle to the labelling beak varies
  • labelling beak is too far from the bottle. No more than 2mm
  • product and/or label sensors to be clean
  • check settings of sensors are correct for the applicable opacity of the backing paper
  • check sturdiness of labelling head/applicator



HOW TO DEAL WITH PROBLEMS INCURRED WITH CERTIFICATION SEALS
  • To prevent downtime, Pyrotec must be contacted directly to investigate the problem.
  • Should it happen that Pyrotec is not available, or should it for example happen during evening shift, then the industry can make use of another seal range. SAWIS must be informed of this as soon as possible.
  • Should Pyrotec’s investigation show that it was a seal problem, a claim can be submitted by the involved institutions for the downtime and additional costs to solve this problem. These claims must be directed to SAWIS. These claims will only be considered if Pyrotec was involved in the investigation.
  • Pyrotec’s conclusion was thus that if the problem was caused by the applications equipment, they themselves have the right to invoice the involved institutions for the costs involved to investigate the problem.

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