TAPPI T551

Introducing TAPPI T 551 – Industrial Physics 

TAPPI T 551 is a global TAPPI standard method that’s used to measure the thickness of paper and paperboard using the soft platen method.  

TAPPI is the technical arm of the American Paper & Pulp Association (APPA), and it gathers and disseminates information concerning production matters. 

The TAPPI T 551 paper testing method describes a procedure for measuring the thickness of a single sheet of paper, or paperboard, using soft synthetic rubber platens against the paper. This is to minimize the effect of surface roughness. 

Because of the relatively high pressure (50 kPa), this paper thickness testing method may not be suitable for measurement of tissue or other soft or low-density materials. This is because the structure may collapse at the prescribed pressure of 50 kPa (7.2 psi). 

Why is paper thickness testing important?

Paper thickness testing using the TAPPI T 551 approach is useful for product control purposes, design of end use products, and for acceptance testing for conformance to specifications.  

The soft platen method largely eliminates the surface roughness effect and, because the platen closing pressure is more uniformly distributed over the test area, partially eliminates the “compressibility effect.” Soft platen thickness gives the same results as effective thickness, which is defined as theoretical thickness – obtained from the relationship of extensional stiffness to bending stiffness. 

TAPPI T 551 paper testing devices  

So, how can Industrial Physics improve your TAPPI T 551 paper testing? 

Technidyne PROFILE/Plus® Thickness 

The PROFILE/Plus® Caliper automatically measures the caliper of paper or board samples. It includes paper feed for automated profile testing.  

Our paper thickness tester was developed to help you to meet the requirements of ISO 534, ISO 18522, TAPPI 411, TAPPI 551 and TAPPI 580. 

Need paper testing solutions? Get in touch 

At Industrial Physics, we’ve specialized in the design and manufacture of testing instruments for pulp, paper, and packaging industries for almost 100 years and have a wealth of experience behind us. 

We like to share our knowledge and, across the knowledgebase section of our website, we publish lots of blogs on related subjects. For example, why not have a look at our quick guide to paper pulp evaluation? Then you could read up on sample preparation for paper testing.  

If you have any questions about TAPPI T 551 paper testing and how we can support you, then just get in touch. 

Your global test and measurement partner for TAPPI T 551