BS 3900-A7

Introducing BS 3900-A7 – Industrial Physics

BS 3900-A7 is a global BSI paint testing method that enables you to determine the viscosity of liquid paints at a high rate of shear.

The British Standards (BS) are the testing standards produced by the BSI Group which is incorporated under a royal charter, formally designated as the national standards body (NSB) for the UK.  

The BS 3900-A7 index of viscosity testing methods were developed for a range of liquid paints, but it excludes chemical tests.  

Why is viscosity testing useful?

The higher the viscosity of a fluid, the more it will resist flow. When you move two fluid layers against one another you create a friction: known as flow resistance. By measuring this resistance, it’s possible to calculate the sample’s viscosity. The formula for working out a sample’s viscosity is a simple one: viscosity = shear stress / shear rate. 

Shear stress is the force per unit needed to move one layer of liquid in relation to the other and shear rate is the measurement of change in speed at which intermediate layers move with respect to one another. The result is often expressed in centipoise (cP), the equivalent of 1 mPa s (millipascal second). 

The BS 3900-A7 paint testing standard contents

Within the BS 3900-A7 viscosity testing standard you will find the following contents included: 

• BS 3900-07 viscosity testing scope 
• Content and usage of BS 3900 paint testing 
• Tests method for liquid paints (excluding chemical tests) 
• Tests involving chemical examination of liquid paints and dried paint films 
• Tests associated with paint film formation 
• Optical tests on paint films 
• Mechanical tests on applied coatings 
• Durability and environmental tests on paint films 
• Evaluation of paint and varnish defects 
• Testing of coating powders 
• Tests for release of biocides from antifouling paints. 

Industrial Physics viscometers and paint testing solutions

So, how can Industrial Physics improve your BS 3900-A7 viscosity testing? 

TQC Sheen Cone and Plate Viscometer CP1
The Cone and Plate Viscometer (CP1) is a standard test for dynamic viscosity testing. It’s faster and more accurate by use of new high precision microprocessor controls. As non-Newtonian fluids exhibit different viscosities relative to the shear rate applied, the Cone and Plate Viscometer tightly controls it to 10.000 s⁻¹ (BS / ISO) or to 12.000 s⁻¹ (ASTM). These are generally accepted to be representative of paint application via a roller or brush and so reflect ‘real world’ application. 

TQC Sheen Digital Rotothinner™ DV2700 

The Digital Rotothinner™ DV2700 is used to measure the viscosity of paint, coatings and inks in P or cP units. We developed this industry-leading Rotothinner viscometer for highly reproducible results and insightful stability analysis. 

Need viscosity testing solutions? Get in touch

We’ve learnt a thing or two about paper and board testing over the decades. Now Industrial Physics is recognized as a brand that likes to bring new, innovative viscometers to market. 

We like to share our knowledge and we’re here to help you to answer your questions about viscosity testing. Across the knowledgebase section of our website we publish lots of blogs on related subjects.   

First up, why not try this blog that explores how to measure viscosity? Then we hope that you find our viscosity calculator and our viscosity conversion table helpful. 

If you have any questions about BS 3900-A7 viscosity testing and how we can help you with other aspects of your paint testing, then just get in touch!

Your global test and measurement partner for BS 3900-A7