Pull up a technical data sheet for almost any adhesive and you will see a viscosity figure, often something like 2,500 cP or 800 mPa·s. If those numbers do not mean much at a glance, this guide is for you. Understanding adhesive viscosity units helps you read spec sheets accurately, match products to your equipment, and catch formulation issues before they become production problems.
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Request InformationThe Most Common Adhesive Viscosity Units
Centipoise (cP) and Millipascal-Seconds (mPa·s)
These are the two units you will encounter most often, and they are numerically equivalent: 1 cP equals 1 mPa·s. Water at 20°C measures approximately 1 cP, which gives you a useful baseline. From there, adhesive viscosity ranges tend to fall like this:
| Viscosity Range | Consistency | Typical Use |
| 50–500 cP | Watery to light oil | Spray systems, curtain coaters |
| 500–5,000 cP | Light to medium syrup | Roller coaters, laminating |
| 5,000–50,000 cP | Heavy syrup to thick paste | Extrusion guns, bookbinding |
| 50,000 cP+ | Paste to putty | Gap filling, product assembly |
Hot melt adhesives are measured in cP at their application temperature, typically between 175°C and 205°C. A reading of 3,000 cP at 175°C tells you how the product behaves while molten in your applicator, not at room temperature. Water-based adhesives are measured at 25°C and can range from a few hundred to well over 10,000 cP depending on solids content and formulation.
Pascal-Seconds (Pa·s)
The Pascal-second is the SI unit for dynamic viscosity, more common in scientific literature and some European supplier specs. The conversion is simple: 1 Pa·s equals 1,000 cP. An adhesive listed at 3.5 Pa·s has a viscosity of 3,500 cP.
Krebs Units (KU)
Krebs units appear occasionally in specs for water-based adhesives with coating-like consistencies, measured using a Stormer viscometer per ASTM D562. They are more common in the paints and coatings world, but worth recognising if they show up on a data sheet.
How Viscosity Is Measured
The Brookfield viscometer is the industry standard for adhesive viscosity testing. It measures the torque required to rotate a spindle through the adhesive at a set speed, reporting results in cP or mPa·s. It is a core tool in adhesive quality auditing because batch-to-batch viscosity consistency is one of the fastest ways to confirm a product is performing to spec.
Always note the temperature alongside any viscosity reading. The same adhesive can measure very differently at 20°C versus 25°C, and a figure without a temperature reference has limited practical value.
What the Unit Tells You and What It Doesn’t
A viscosity figure reflects lab conditions. It does not automatically predict how an adhesive will behave under the shear rates, pressures, and temperatures of your production line. Most adhesives are also non-Newtonian, meaning their viscosity shifts under mechanical stress, thinning during pumping, then recovering body once applied. This thixotropic behaviour is useful but it means viscosity alone does not tell the whole story.
When a product is stringing, sagging, not wetting correctly, or clogging equipment, viscosity is often the first variable to investigate. If your current formulation is not quite right, custom formulation allows for viscosity adjustments tailored to your specific equipment and application requirements. For a broader review of how your adhesive is performing, an adhesive audit is a practical place to start.
Talk to a Viscosity Expert
Reading a viscosity unit correctly is one thing. Matching it to the right adhesive for your application is another. If you have questions about spec interpretation or want to review your current adhesive setup, contact us and one of our technical advisors will help.
