Thin-to-thick transition
Lotions, shampoos and gels may be too thick for simple gravity filling but not as heavy as industrial pastes.
Viscous liquid filling
Viscous liquid filling machines for thick, sticky and slow-flowing products.
A practical route for products that sit between standard liquid filling and full paste filling, including gels, lotions, shampoos and semi-viscous products.
Piston and volumetric fillingSemi-auto to automatic linesUK advice and support
10–5000mlcommon dosing ranges
Pistoncontrolled viscous fills
Line-readyfill, cap and label
Viscous liquid filling
Not sure whether you need a liquid filler or a paste filler?
Use this route when your product is thicker than a free-flowing liquid but may not need a heavy paste filler. Terms such as viscous liquid filling machine, thick liquid filler, gel filling machine and high-viscosity liquid filler all need the same practical specification check.
Viscosity alone is not enough. Foaming, tailing, solids, temperature, fill size and container opening all influence the equipment route.
Product behaviourViscosity, temperature, particulates, aeration, stringing, settling and whether the product changes during the day.
Fill requirementTarget fill volume, tolerance, dose range, container neck opening, headspace and whether the fill is by volume, level or weight.
Container and closureJar, bottle, tub, cartridge, pail or jerrycan dimensions, cap style, labelling area and pack stability on conveyors.
Production targetRequired bottles per minute or per hour, number of SKUs, changeover frequency, cleaning process and operator involvement.
Foamy products
Detergents and shampoos can need slower filling, diving nozzles or product handling adjustments to avoid foam and trapped air.
Sticky products
Honey, syrup and gels need clean cut-off and may need heating or a different feed arrangement.
Not sure whether it is liquid or paste?
Send the product, viscosity notes and container details. The specification can be narrowed before you commit to one machine family.
What counts as a viscous liquid?
A viscous liquid is thicker than a free-flowing liquid and may need slower filling, different pumps, larger nozzles or positive-displacement dosing.
Is a viscous liquid filler the same as a paste filler?
There is overlap. Some products sit between liquid and paste, so the machine route should be selected after reviewing viscosity, foaming, stringing and container type.
Can viscous liquid fillers handle shampoo and gels?
Yes, many viscous liquid applications include shampoos, gels, lotions and detergents, but foaming and product compatibility need checking.
Viscous-product boundary
Decide whether the application is controlled by flow, displacement or product condition.
A product can be called a “liquid” and still need paste-filling features. The practical boundary is whether it flows into the dosing system consistently, whether pressure or temperature changes its behaviour and whether the nozzle can stop the product cleanly.
Free-flowing or foaming liquids
Gravity, overflow, peristaltic, diaphragm or other liquid-filling methods may be more suitable when the product flows readily, foams, requires fill-to-level presentation or needs a tubing-only product path. Compare the broader Lancing liquid fillers range rather than forcing a paste-filling solution.
Thick but smooth products
Piston or pump-based positive displacement often becomes relevant where a controlled dose must be drawn and discharged despite high resistance to flow. Confirm product feed, chamber refill and cut-off at the normal filling temperature.
Particulate or fibrous products
Viscosity is only one issue. Measure the largest piece and review every restriction. A route that handles the base sauce may still block on herbs, seeds, fruit pieces or fibres.
Elastic or stringy products
Products that stretch after the valve closes may need a shut-off nozzle, suck-back or a different product path. The test should include the real time between containers and the required neck cleanliness.
| Condition to record | Why it matters | How to make the trial repeatable |
|---|---|---|
| Product temperature | Can change viscosity, pressure, dose time and cut-off. | Record temperature at the hopper and nozzle during the run. |
| Time after mixing | Settling, aeration or thickening may change later fills. | Test at a representative batch age and standing time. |
| Feed level or pressure | Can alter refill consistency and pump performance. | Use the planned hopper or supply arrangement and record its operating window. |
| Container opening | Limits nozzle diameter and affects splash or smear. | Use production packs and the smallest intended opening. |
Shortlist evidence
Use a product sample to prove the boundary between liquid and paste filling.
Send a sample, pack and process information. Lancing can compare the real fill against piston, pump and other routes instead of relying on an approximate viscosity label.
Product movement
Can the product enter the dosing system without cavitation, air pockets or excessive pressure?
Dose control
Does the selected principle remain repeatable across the required fill range?
Finished presentation
Does the nozzle leave the neck and outside of the container clean enough for closure and labelling?
Viscous filler FAQs
Questions at the liquid-to-paste boundary.
Is there one viscosity number that defines a paste filler?
No. Pumpability, particles, temperature, elasticity, air content and the pack opening can be more important than a single viscosity figure.
Why should temperature be recorded during a trial?
Many products change viscosity as they warm or cool. Without temperature, a speed or accuracy result may not be reproducible in production.
Can a viscous liquid be filled by gravity?
Some can, but fill time and cut-off may be poor. The correct method should be tested against output, accuracy and presentation requirements.
When is a peristaltic filler more suitable?
Peristaltic filling can be useful for compatible lower-viscosity products or applications needing a tubing-only path. Very thick products and large doses may require another route.
What causes a viscous product to fill inconsistently?
Common causes include changing temperature, trapped air, inconsistent hopper feed, particles, incomplete chamber refill, seal leakage or variable operator timing.
What should be sent for a viscosity review?
Send the product sample or data, fill temperature, largest particles, dose range, pack opening, target output and a video showing how the product flows at the point of fill.