Container stability
Flat bottles need consistent orientation and guide control so labels do not skew as the bottle moves through the conveyor.
Flat bottle labelling
Flat bottle front and back labelling machines
Flat bottles need controlled presentation through the labelling station so front and rear labels land squarely on the correct panel. A twin-side labeller uses side labelling heads with guide rails and hold-down control to apply two labels during one pass.
Selection points
What to check before choosing a machine
- Suitable for flat plastic, glass or metal containers used in cosmetics, household, chemical and food products.
- Can support front branding labels and rear ingredient, barcode or safety labels.
- Guide rails, side belts and pressure plates are selected around container width, height and stability.
- Coding and inspection can be planned around the same line layout where required.
Label registration
Front and back label start points need setting around bottle face, label gap, sensor type and product speed.
Changeover planning
Width, height and pressure settings should be easy to repeat across different SKUs and label sizes.
Related routes
More front and back labelling applications
Use these pages to compare similar pack formats and label application routes.
Flat bottles
Front and rear labels on flat and rectangular containers.
Oval bottles
Controlled labelling for shaped and oval packs.
Round bottles
Separate front and back labels rather than full wraparound.
Cartons and flat packs
Top, bottom and face labelling for flat products.
Need help with flat bottle labelling?
Send your pack dimensions, label size, label material and output target. Lancing UK can help shortlist the most suitable front/back labelling route.
Flat bottle engineering
Use the usable label panel, not the overall bottle width, as the placement datum
A flat-sided bottle can still include shoulder taper, heel radius, mould seams, recessed panels or flexible walls. The front and back label positions should be defined from repeatable pack features and kept clear of transitions that prevent even wipe-down.
Keep the bottle square through both label heads
Side guides establish the product path, while side belts or pressure devices can stabilise the bottle through the dispense and wipe-down zones. The contact area should be chosen so the container remains upright without being squeezed or deflected. Tall, narrow or partly filled bottles may need additional control because their centre of gravity can move during acceleration.
When the front and back labels differ in length, each applicator should be set independently while both positions refer to the same bottle datum. The label trigger, dispense delay and wipe-down should be checked at normal product spacing, not only with isolated bottles placed by hand.
- Measure the flat panel between the shoulder, heel and side radii.
- Identify mould seams, embossing, handles and recessed areas.
- State whether the bottle is plastic, glass or metal and whether it is filled.
- Mark the nominal front and back positions on a drawing or sample.
A placement tolerance is only meaningful when the pack datum, measurement direction, sample condition and test speed are defined.
| Panel feature | Specification or trial question |
|---|---|
| Flatness and recess | Does the label contact one continuous surface, or must it bridge moulding, embossing or a recessed panel? |
| Shoulder and heel transition | How much clearance is needed above and below the label so its edges remain on a stable surface? |
| Side radius | Can the label be fully wiped down before the panel curves away, and is the artwork positioned within that usable width? |
| Mould seam or container joint | Will a label edge cross a seam that changes adhesion, appearance or barcode readability? |
| Bottle rigidity | Can side-belt and wipe-down pressure be applied without squeezing the pack or changing the label datum? |
| Guide contact zone | Is there a consistent area for rails or belts that does not touch a pump, trigger, handle or the intended label? |
| Coding and inspection | Where will variable data be printed, how will it be checked and can the reject system remove an incorrectly labelled pack? |
Common failure modes to reproduce during the trial
- Label skew caused by a bottle leaning or entering at an angle.
- Edge lift where the label reaches a shoulder, heel or side radius.
- Different front and back heights because the two heads use inconsistent datums.
- Bubbles or wrinkles caused by panel recess, dust, moisture or uneven wipe-down.
- Product deformation from excessive guide, belt or pressure-plate force.
Acceptance evidence to retain
- Both production label-roll specifications and winding directions.
- Recorded guide, belt, head and sensor settings for each format.
- Measured front and back samples from normal steady running.
- Results after a stop/start and a completed format change.
- Confirmation of coding, inspection and downstream transfer.
Flat bottle questions
Details that affect the final machine setup
Can a front and back labeller use two different label sizes?
Yes, twin applicators can be configured with separate label rolls and independent positions. Both label specifications and the required relationship between them should be supplied for the trial.
How much flat panel area is required?
There is no single universal minimum. The usable area depends on label dimensions, side radius, shoulder and heel transitions, wipe-down method and the container material, so a drawing or production sample is needed.
Can flat plastic, glass and metal bottles be handled?
Each material can be considered, but rigidity, surface finish, weight and friction affect guide pressure, side-belt contact and adhesion. The intended production container should be tested.
Can coding and label inspection be integrated?
Yes, coding, barcode or label-presence inspection can be planned with the labeller where the required print area, controls, product spacing and reject method are defined during line specification.
Labelable panel review
Check recesses, seams and radii before fixing label size
A flat-sided bottle may still have a recessed panel, mould seam, rib or edge radius that limits the area available for reliable wipe-down.
| Panel edge | Keep the label clear of abrupt radii unless the label construction and wipe-down have been trialled across the transition. |
|---|---|
| Recess | Confirm the applicator can press the label into the panel without the surrounding rim blocking contact. |
| Mould seam | Mark raised or irregular seams on the drawing and avoid placing critical print or barcode areas over them. |
| Flexible wall | Test filled and empty states where guide or wipe-down pressure can change the surface shape. |
Panel design questions
Questions about flat and recessed label panels
A nominally flat bottle still needs usable panel boundaries that keep the label away from abrupt radii, seams and unstable surfaces.
How close should a label run to a shoulder, base radius or side edge?
There is no universal edge distance because label stiffness, adhesive, bottle curvature, mould tolerance and wipe-down method all affect whether the label remains flat. The label should sit inside a panel area that can be contacted consistently without forcing the material over an abrupt change in geometry.
Confirm the boundary with a drawing and production-equivalent samples.
What if the front and back panels are not parallel?
Non-parallel panels can require different head angles, guide references or label positions on each side. Using one nominal centreline for both faces may create a visually unequal result even when each head repeats accurately.
Treat the two faces as separate applications, record their datums independently and verify the pack remains controlled between them.
Can a recessed panel be labelled without trapping air at the edge?
It may be possible when the label fits inside the recess, the panel is sufficiently regular and the wipe-down device can contact the material progressively. Problems arise when the label crosses the recess wall or the applicator first seals the perimeter and traps air beneath the centre.
Use the final label construction and bottle samples to prove the application sequence.
How should mould seams, ribs or embossing be treated in the label design?
Keep critical label edges, barcodes and small text away from raised seams, ribs and embossed features where possible. These features change contact pressure and can create local lift, bubbles or visible distortion.
If the artwork must cross them, include the worst production samples in the trial and agree what visual finish is acceptable before ordering the machine.