AATCC 133 - Colorfastness to Heat: Hot Pressing

The AATCC Test Method 133 – Colorfastness to Heat: Hot Pressing is used to determine the resistance of color change or transfer in textiles when exposed to high heat.

The specimens are conditioned in accordance with ASTM D1776 before being tested. The bottom plate of the hot press is covered with the appropriate heat resistant sheeting: wool flannel and dry, undyed cotton cloth. The specimen for testing is placed on top of these layers before the top plate of the hot press is brought down. The top plate is left down for 15 seconds at a temperature based on the ironing instructions of the textile care label. ANSI/ISEA 107 instructs that only dry samples are required to be tested.

Once completed, the sample is evaluated for color change against a pristine specimen in a lightbox in D65, artificial sunlight, against the AATCC Gray Scale for Color Change. The heat resistant sheeting is evaluated for staining in a lightbox with the AATCC Gray Scale for Staining. To pass, the specimen shall be at least a grade 4.5 for color change, and at least a grade 3.0 for staining.

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