Measuring the Mechanical Properties of Leather and Textiles – Compression and Penetration Tests

LEATHER LOOP COMPRESSION 

The leather loop test is used to give an indication of softness. A loop of leather is held in a spring-loaded clamp and a platen used to apply a compression/de-compression cycle test on the loop. Measurements of the force exerted on the leather during the compression stroke (applied energy) and the force exerted by the leather during the decompression stroke (recovered energy) are recorded. The ratio of the recovered /applied energy is calculated and defined as the “springiness” of the sample. This parameter is a good measure of the softness of the leather. 

Leather Loop Compression testing 

PENETRATION TESTS 

Penetration measurements can be used to test the tensile and time-dependent properties of materials. 

Lastometer Rig and illustration of a typical test

Lastometer 

Example leather standard: ISO 3378. 

Also known as the ‘Ball Burst Test’, the Lastometer Rig identifies the strength and distension of the grain. This test exceeds the requirements of the standard method, as grain crack is measured without stopping the test. ‘Material Yield’ at grain crack is also accurately identified. Additional results for this test include the strength and distension of the grain at grain crack and ball burst, and the distance between grain crack and ball burst. The Lastometer rig comprises of the specimen holder and penetrometer. 

The Bagginess Test Rig and illustration of a typical test

Bagginess 

Example leather standard: EN14689. 

Upholstery leather that was originally smooth is often blamed for stretching and becoming wavy after use. This phenomenon is known as ‘bagginess’ and is a feature upholstery tanners test for. This property is caused by ‘creep’ or ‘relaxation’ – permanent deformation over time. It may be seen as waviness of the leather on what was originally a smooth cushion cover on upholstered furniture. The Bagginess Test Rig offers a method that automatically measures the bagginess of leathers. 

The Bagginess Test Rig meets the CEN Standard for determining the bagginess of leather together with its creep and stress relaxation properties after repeated loading. Bagginess is the permanent deformation or retained set in the material measured after the removal of a defined force applied for a specific time. 

Textile Burst test illustration

Textile Burst Test 

Example textiles standard: ASTM D3787. 

A similar concept to the ball burst and lastometer tests for leather, this method is useful for measuring the tensile properties of textiles that can achieve a high strain before failure. A force is applied to a clamped textile sample via a spherical plunger until it breaks. The maximum force achieved is recorded as the breaking force.

Read the next instalment Measuring the Mechanical Properties of Leather and Textiles – Tear and Peel Tests on the blog next week. 

There is a Texture Analysis test for virtually any physical property. Contact Stable Micro Systems today to learn more about our full range of solutions.

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For more information on how to measure texture, please visit the Texture Analysis Properties section on our website.

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