COMPARISON · DISPERSION · MIXER SELECTION
The two terms are routinely confused in specifications, and the confusion is expensive: they describe different machines with different shear mechanisms, different viscosity ranges and different jobs in the process.
A high speed disperser uses a saw-tooth disc to wet powder into liquid at low to medium viscosity. A high shear disperser uses a rotor-stator head to create intense local shear, typically for emulsification or fine deagglomeration.
A high speed disperser turns a large toothed disc at high tip speed. The disc creates a circulating flow pattern and a high-shear zone at its edge; the job is wetting powder and breaking soft agglomerates across a whole batch.
A high shear disperser, or high shear mixer, uses a rotor turning inside a close-fitting stator. Material is drawn in and forced through narrow slots, so the shear is intense but confined to a small volume, and the machine is usually designed to pump product through that zone.
High speed disperser: pigment wetting, pre-mixing and letdown in paints, inks and coatings. It is the first machine in most wet processes, and its disc diameter is set as a proportion of vessel diameter.
High shear disperser: emulsification, homogenisation and fine deagglomeration where droplet or particle size depends on intense local shear. It is common in creams, lotions, adhesives and inline processes.
Buying a high speed disperser for an emulsification duty gives poor droplet control; buying a high shear mixer to wet out a tank of pigment gives a slow, uneven premix. Both mistakes are common when the specification says only 'high shear disperser'.
The practical test is the job: does the material need the whole batch circulated and wetted, or does it need intense shear in a small zone? That answer selects the machine, not the label.
| Criterion | High speed disperser | High shear disperser (rotor-stator) |
|---|---|---|
| Working element | Saw-tooth disc | Rotor inside a slotted stator |
| Shear zone | At the disc edge, across the batch | Confined, high intensity |
| Typical viscosity | Low to medium (up to ~50,000 cP) | Low to medium; paste versions exist |
| Main job | Powder wetting, pre-mix, letdown | Emulsification, homogenisation, fine deagglomeration |
| Typical capacity | 50 – 5,000 L (single shaft) | Batch or inline, sized to flow |
| Common industries | Paints, inks, coatings, agrochemicals | Creams, adhesives, food, fine chemicals |
Use a high speed disperser when the task is wetting powder into a batch and preparing a millbase.
Use a high shear rotor-stator when the task is droplet size, emulsion stability or fine deagglomeration in a small volume.
No. High speed refers to disc tip speed in a saw-tooth disperser. High shear refers to a rotor-stator head that generates intense local shear. A machine can be high speed without being high shear.
Poorly. It can create a coarse emulsion, but droplet size control needs the confined shear of a rotor-stator.
Not efficiently at production scale. The shear zone is too small to circulate a full batch, so wetting is slow and uneven.
The high speed disperser. It prepares the millbase; rotor-stator machines are used later or for specific products.
Combined machines exist, typically a saw-tooth disc plus a rotor-stator on a second shaft. They are useful where a single vessel must do both jobs.
Describe the product, the batch size, the target fineness and how often you change product. POLYC MACHINE engineers will tell you which machine fits — and where a trial is required before performance is guaranteed.