The colorfastness rating is determined using a gray scale or color scale, which provides a standardized reference for evaluating the degree of color transfer or staining on the test specimen. The scale consists of a series of color patches or shades that range from light to dark, typically in increments of staining or color change.

Here's a general process for determining the colorfastness rating using a gray scale or color scale:

1. After the rubbing process is completed, the test specimen and rubbing head are separated.

1. The test specimen is compared to the color patches on the gray scale or color scale. The color patches typically have a rating or designation associated with them, such as "1" for no color transfer or staining and "5" for severe color transfer or staining.

1. The colorfastness rating is determined by matching the appearance of the test specimen to the closest color patch on the scale. For example, if the test specimen shows no color transfer or staining, it may be rated as "1" on the scale. If there is slight staining, it may be rated as "2," and so on.

1. The colorfastness rating provides an indication of the material's resistance to color transfer or crocking. Higher ratings (closer to "1") indicate better colorfastness, while lower ratings (closer to "5") indicate poorer colorfastness.

It's important to note that different standards and test methods may use slightly different scales or criteria for colorfastness evaluation. The specific scale and rating system used may vary depending on the industry, country, or testing organization. Manufacturers and testing laboratories typically follow relevant industry standards or specifications when conducting colorfastness testing.