Knowledge Base
Viscosity testing in paints and coatings glossary and fact sheet
Key terms
| Term | Definition |
| Viscosity | A fluid’s resistance to flow. |
| Dynamic viscosity | Resistance to flow under an applied shear, measured in pascal seconds (Pa.s), poise (P), or centipoise (cP). |
| Kinematic viscosity | Dynamic viscosity divided by density, measured in centistokes (cSt); what a flow cup effectively reports. |
| Shear rate | The rate at which a fluid is deformed, in reciprocal seconds (s-1); higher during spraying, lower during leveling. |
| Newtonian | A fluid whose viscosity does not change with shear rate. |
| Non-Newtonian | A fluid whose viscosity changes with shear rate; most paints and coatings behave this way. |
| Thixotropy | A time-dependent thinning under agitation and recovery at rest. |
| Krebs unit (KU) | A paint viscosity scale derived from the Krebs paddle method at 200 rpm. |
| Flow cup | A cup with a precision orifice; drain time in seconds indicates viscosity. |
| Cone and plate | A geometry measuring dynamic viscosity at a tightly controlled high shear rate. |
Standards reference
| Standard | Scope | IP standards page |
| ISO 2431 | Flow time of paints and varnishes using flow cups. | Live |
| ISO 2884 | Determination of viscosity using rotary viscometers; part 1 is cone-and-plate at high shear. | Live (general page) |
| DIN 53211 | Flow time of paints and coatings using the DIN flow cup. | Live |
| ASTM D4287 | High-shear viscosity by cone-and-plate viscometer. | Not linked in this hub |
| BS 3900-A7 | Determination of viscosity (British Standard) referenced by cone-and-plate. | Not linked in this hub |
| ASTM D2162 | Basis for certified viscosity calibration oils. | Not linked in this hub |
Instrument quick facts
| Instrument | Method | Key figures |
| TQC Sheen Digital Krebs Viscometer DV2300 | Krebs paddle at 200 rpm | About 37 to 141 KU (10 to 5,000 cP); accuracy 2 percent of full scale. |
| TQC Sheen Cone and Plate Viscometer CP1 | Cone-and-plate, high shear | Shear controlled to 10,000 s-1 (BS/ISO) or 12,000 s-1 (ASTM). |
| TQC Sheen Digital Rotothinner DV2700 | Rotational, 3 modes | 0.1 to 350 poise (10 to 35,000 cP); manual, max-hold, timed. |
| TQC Sheen Multi Spindle Viscometer | Brookfield method | Broad range via interchangeable spindles. |
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Related Products
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TQC Sheen Krebs Viscometer
The TQC Sheen Krebs Viscometer DV2300 is a digital rotational viscometer that measures paint and coating viscosity using the KREBS method - a paddle rotating at a constant 200 rpm in a fixed volume of sample. It converts torque into three simultaneous outputs: Krebs units (KU), centipoise (cP) and grams (g), with automatic unit conversion shown on the LCD display. Used by paints and coatings QC laboratories, paint manufacturers, automotive OEM coating suppliers, printing ink producers, adhesive manufacturers and cosmetics QC labs, the DV2300 supports ASTM D562 Krebs-unit specifications alongside direct viscosity readings for a wide range of Newtonian and near-Newtonian fluids.
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Online Range
TQC Sheen Multi Spindle Viscometer
Our modern digital viscometer conforms to the Brookfield method and it’s ideal for a wide range of viscosity testing applications.
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Online Range
TQC Sheen Viscosity Cups (Dip/Immersion), according to ISO 2431
The TQC Sheen Viscosity Cup ISO 2431 (Dip/Immersion) is a flow-time viscosity cup compliant with ISO 2431 - in dip/immersion form with a handle for point-of-use paint and coating viscosity checks directly from the container. Available in multiple orifice sizes covering the paint viscosity working range.
FAQs
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It depends on the product and how it is applied. Use a flow cup for a quick check of thin products, a Krebs viscometer for mid-range decorative paints in KU, and a cone-and-plate viscometer for dynamic, high-shear measurement of non-Newtonian coatings.
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A flow cup measures how long a sample takes to drain through an orifice, giving a fast, relative kinematic reading. A rotational viscometer measures the torque needed to turn a spindle, cone, or paddle in the sample, giving dynamic viscosity and the ability to measure at a controlled shear rate, which matters for non-Newtonian coatings.
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The TQC Sheen Cone and Plate Viscometer controls shear to 10,000 s-1 for BS and ISO methods, or 12,000 s-1 for ASTM. These rates represent application by roller or brush, so the measured viscosity reflects how the coating behaves in real use rather than at rest.
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Viscosity is strongly temperature dependent, so a small change in sample temperature can shift the result. Reliable testing means measuring at a defined, stable temperature, and comparing results only when they were taken under the same conditions.
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Krebs units (KU) are a paint viscosity scale from the Krebs paddle method, in which a paddle turns in the sample at 200 rpm and the torque is converted to KU. The Digital Krebs Viscometer reports KU, centipoise, or grams, and is widely used for architectural and decorative paints.
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