TAPPI T460

Introducing TAPPI T460 – Industrial Physics

TAPPI T460 is a global TAPPI standard method that’s used to measure the air resistance of paper using the Gurley porosity testing method. 

This TAPPI porosity test measures the amount of time required for a certain volume of air to pass through a test specimen. The air pressure is generated by a gravity-loaded cylinder that captures an air volume within a chamber using a liquid seal. 

What is air resistance testing?

Air resistance is the resistance to the passage of air, offered by the paper structure, when a pressure difference exists across the boundaries of the specimen. To measure it, you’ll need to work out the time it takes for a given volume of air to flow through a specimen of given dimensions. Air resistance tests should be performed under specified conditions of pressure, pressure difference, temperature, and relative humidity. 

The air resistance of paper may be used as an indirect indicator of Z-directional fluid permeance. It’s also a useful test to help you with other variables such as degree of refining, absorbency (penetration of oil, water, etc.), apparent specific gravity, and filtering efficiency for liquids or gasses.  

Air resistance is influenced by the internal structure and also the surface finish of the paper. Internal structure is controlled by the type and length of fibers, degree of hydration, orientation, and compaction of the fibers. It’s also affected by the type and amount of fillers and sizing.  

The Gurley porosity testing technique assesses the air permeance of paper and board using an air resistance tester or a porosity tester. It’s carried out using the Gurley apparatus and is suitable for papers and boards with an air permeance of between 0,1 µm/(Pa•s) and 100 µm/ (Pa•s).  

TAPPI T460 air resistance testing

The TAPPI T460 porosity testing method is used to measure the air resistance of approximately 6.45 sq. cm. (l sq. in.) circular area of paper using a pressure differential of 1.22 kPa. 

This pressurized volume of air is directed to the clamping gasket ring, which holds the test specimen in place. Air that passes through the paper specimen escapes to the atmosphere through holes in the downstream clamping plate. 

This TAPPI testing method measures the volume of air that passes through the test specimen, along with any possible leakage of air across the surface. It’s unsuitable for rough-surface papers which cannot be securely clamped to avoid significant surface and edge leakage. 

TAPPI T460 testing devices

So, how can Industrial Physics improve your TAPPI T460 testing? 

PROFILE/Plus Porosity 

The PROFILE/Plus® Porosity tester gives you automated paper roughness and porosity measurements to international standards.  

Brought to you by Technidyne, our specialist optical, surface, and physical property testing brand, the PROFILE/Plus® Porosity helps you to achieve a uniform paper surface for high-quality printing.  

Technidyne PROFILE/Plus® Roughness Sheffield with Porosity 

The Profile/Plus Roughness Sheffield with Porosity accurately and automatically measures surface roughness of paper and air permeance to industry standard methods. 

Brought to you by Technidyne, our specialist optical, surface, and physical property testing brand, this Profile Plus device is an industry-leading automated roughness of paper and porosity tester. 

Need TAPPI T460 testing solutions? Get in touch

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

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

While on the subject of water absorption, why not check out our blog on how to test surface porosity with 3 techniques. Or perhaps you’d prefer this read on testing the physical and optical properties of paper. 

If you have any questions about TAPPI T460 and how we can help you with your air resistance testing, then please just get in touch!

Contact us – Industrial Physics 

Your global test and measurement partner for TAPPI T460