Fabric Heat Shrinkage Test

Determine the dimensional stability and colour change when subjected to hot pressing. Test to be done for fabrics with more than 50% synthetics.

Apparatus required:

Heating device, e.g. iron press, providing even heat transfer to the specimen from the top by close contact at a controlled temperature and a given pressure of 2 bars.

Test specimen:

• Cut one pieces at least 40 x 40 cm out of the fabric. Lay the fabric plain on a table and mark with three 35 cm pairs of bench marks parallel to the width as well as to the length to the fabric.
• Cut another white piece in size 40 x 40 cm out of the same fabric. Instead of the same fabric also white cotton fabric can be used.

Procedure:

1. Lay the fabric flat on the bottom plate of the press. Place one dry, white cotton fabric or the same fabric as specimen but undyed, on top of the specimen, lower the top plate of the heating device and leave the specimen for 15 seconds at a temperature of 170 °C. Polyamide fabrics must be tested at 160°C.
2. Let the test fabric cool down on the bottom plate of the press.
3. Remove the specimen and let the fabric relax under 20°C ± 2°C and 65 % ± 2% RH For 4 hours.

Evaluation:

• Lay the specimen on a flat surface without stretching. Measure and record the distance between each pair of benchmarks to the nearest millimeter and calculate the dimensional change.
• Colour change of the specimen must be assessed with the grey scale accord. ISO 105 -A02
• Pressure mark must also be assessed.