ASTM D6116 Standard Test Method for Blocking

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ASTM D6116 provides a leather blocking resistance evaluation method that accredited laboratories offer as a testing service. These laboratories provide detailed analytical reports that include blocking ratings, ease-of-separation ratings, and assessments of grain damage or finish peeling. Manufacturers use the results to evaluate leather materials against quality specifications and improve their suitability for finished products. The results also enable manufacturers to identify potential production problems and maintain consistent product quality and customer satisfaction. 

• Determines the resistance of leather to blocking under controlled temperature, humidity, and pressure conditions.
• Applies to completed and coated leather products.
• Simulates conditions that leather may encounter during storage and processing.
• Uses SI units as the standard units for reported values.
• Provides two alternative procedures: the Petri dish method and the perspirometer method.
• Assesses the ease of separation on a pass/fail basis through visual evaluation of surface damage.

What are the Uses of ASTM D6116 Testing?

ASTM D6116 testing assists laboratories in evaluating the blocking resistance of finished leather materials. Manufacturers and engineers use the results for quality control, product development, and process optimization. This standard-

• Evaluates the blocking resistance of coated and finished leather.
• Determines the adhesion that develops between leather surfaces under heat and pressure.
• Supports quality control during leather processing and manufacturing.
• Identifies potential blocking problems during storage and transportation.
• Minimizes production delays and material damage caused by surface adhesion.
• Supports product development and formulation optimization.
• Assists supplier qualification and material verification programs.

Which Materials Can Be Tested Under ASTM D6116?

ASTM D6116 applies to leather materials that manufacturers finish and coat for use in the blocking resistance test. The method can be used for various leather materials such as shoe upper leather, garment leather, and upholstery leather. The technique cannot be used on wet blue leather. The analyst identifies the leather type and coating finish and prepares the specimen properly to obtain accurate results. 

Why is ASTM D6116 Important?

ASTM D6116 is a standard method for measuring the blocking resistance of leather materials after processing. Blocking is a significant problem in leather processing, storage, and transportation. When stacked under pressure and elevated temperature, coated or finished leather surfaces can adhere and damage the surface, causing the finish to peel and the product to be rejected. The test results can be used to assess leather quality, compare leather quality across different leather products, and ensure consistent processing performance. These findings also help manufacturers and engineers avoid production problems and ensure product quality. 

ASTM D6116 Testing Process and Data Collection

The technician cuts the leather samples and places them in water at 23 ± 2°C for 4 hours. The technician extracts the specimen and folds it in half. The technician folds the specimen and places it under pressure in a Petri dish with a 2000 g weight or in a perspirometer. The technician puts the assembly in an oven at 80 ± 3°C for 2 hours. After removing the assembly from the oven, the technician allows the specimen to cool for 30 minutes. The technician carefully unfolds the fold by hand and checks for ease of separation, damaged grains, and finish peel. The lab makes a pass or fail judgment on the visual assessment and records the blocking rating. 

Common Challenges and Troubleshooting

ASTM D6116 testing fails to produce accurate results when technicians apply the pressure incorrectly, the pressure isn’t consistent, or the temperature is not controlled. Blocking varies depending on the leather type and thickness. Technicians always maintain proper conditioning time and temperature during specimen preparation to meet the standard. The technicians also adjust the oven temperature and check the applied weight or pressure. If there are any significant differences between repeated measurements, the laboratory must confirm the validity of the specimen preparation, conditioning, testing conditions, or evaluation procedure before reporting the final measurement. The standard has no precision data or bias data, and users are advised to check the reliability of the method using reference samples. 

• The laboratory reports blocking resistance using the applicable Pass/Fail classification, such as 1-Pass or 2-Fail, rather than a numerical unit.
• The analyst records the ease of separation and documents surface damage, including finish peeling, grain damage, or other visible deterioration.
• The technician records the applicable test method, temperature in °C, pressure in the specified unit, and other relevant test conditions.
• The laboratory compares the blocking resistance classifications and observed surface condition among leather samples to evaluate consistency under the specified test conditions.
• The analyst uses the blocking resistance results and observed surface condition to assess the leather’s suitability for storage, transportation, further manufacturing, or intended end use.

Link to ASTM D6116