A homeowner decided to wash a set of red living room curtains for the very first time, carefully following the cleaning instructions listed on the label. He avoided bleach products and washed the curtains on the delicate cycle setting. But despite his diligence, the color nonetheless faded significantly after washing; his once-red curtains were now a shade of faded pink, and they no longer matched the color scheme of the living room.
This is a common challenge that textile manufacturers face, whether they’re dyeing textiles for curtains, blankets, clothing or any other colorful fabric. If a large-scale textile manufacturer fails to identify problems with fading or color bleeding in its products early on, it could lead to customer dissatisfaction later. Yet there is a solution to this problem. Using the Grey Change and Grey Stain color scales, which are included in the software packaged with some advanced spectrophotometers, textile manufacturers can identify both fading and bleeding early on in the dyeing process. These two color scales are specifically designed to analyze color fastness and dye durability, allowing manufacturers to refine their dyeing processes and invest in the most durable dyes for their products.
The Problem with Some Colorful Textile Dyes
Certain textile dyes are more prone to fading and bleeding than others and environmental factors like exposure to UV rays or frequent washing can significantly alter product color depending on the chemical makeup of the dye.1 This is why textile manufacturers must consider the color fastness of the dye being used for each product, as different types of dyes will have different benefits and downsides.
The term “color fastness” refers to a dye’s durability against fading and bleeding; a dye that has excellent color fastness will be durable and long-lasting, even when exposed to environmental factors that cause color fading or bleeding. A dye with poor color fastness won’t be as durable. For instance, one type of dye that is known for its excellent color fastness is an azoic or naphthol dye.2 These dyes produce bright, bold colors, especially in the red and orange spectrum, and are highly resistant to fading in the wash or even when exposed to bleach. Conversely, acidic dyes tend to be resistant to color fading when they’re exposed to sunlight, but they’re much more prone to fading and bleeding after washing. Here are a few more examples of common textile dyes and their typical color fastness:
- Basic: Excellent light and wash fastness.
- Disperse: Good light and wash fastness, but sensitive to nitrogen gas.
- Direct: Fair lightfastness, but very poor wash fastness.
- Reactive: Great light and wash fastness, but prone to bleeding excess dye unless it’s washed well during manufacturing.
- Mordant: Good light and wash fastness, but only available in a small range of colors.
- Premetallized: Good light and wash fastness, but only available in a small range of colors.
- Sulphur: Fair light and wash fastness.
- Vat: Excellent color and wash fastness. It’s perhaps the most durable textile dye used by manufacturers.
- Fluorescent brighteners: Fair wash fastness, but very poor lightfastness.
While this basic list of color fastness can give you a general idea of which textile dyes will be the best choice for your textile products, the list isn’t foolproof. For example, although sulphur dye is generally fairly resistant against color fading after being washed or exposed to sunlight, some manufacturers have found that certain sulphur-dyed yarns will occasionally fade after about six months of use. This is why it’s important to test your dyes for true color fastness using the Grey Change and Grey Stain scales; every dye reacts differently with each fabric you use, so by testing each new product in advance, you may produce more durable, colorful textiles.
Using Grey Change and Stain Scales to Ensure Color Fastness
Both the Grey Change and the Grey Stain color scales can help you refine which textile dyes you use to create your products as well as evaluate your dyeing processes. These color scales work by comparing a textile’s baseline color (the color of the product shortly after being dyed) to the color of the product after it has been washed or exposed to light. While it’s possible to perform a rough version of this color analysis using visual assessment alone in some cases, you may not detect a subtle change in color between washed and unwashed textiles with the naked eye. More importantly, visual assessment does not allow you to distill your observations to the objective data necessary for meaningful color comparison, communication, and correlation to process variables. A spectrophotometer can help you detect, record, analyze, and communicate even subtle color changes in color after the very first wash as well as over time, allowing you to determine whether the dye you’re using is durable enough for your products and identify areas of potential process improvement.
The Grey Change Scale Detects Early Fading
To best detect color fading, you can use the Grey Change scale, which identifies even subtle losses of color in textile samples. The Grey Change scale works by comparing the baseline color of the sample to five pairs of grey standards, each representing a different stage of color fading. First, you can measure the color of your product sample using a spectrophotometer. From here, you can then wash your sample and re-measure the color, comparing it to the original with the Grey Change scale. If the sample receives a Grey Change scale rating of 5, that means there was no color loss whatsoever. If, however, the sample receives a Grey Change scale rating of 1, almost all of the sample’s color was lost during washing. Generally, dyes with good color fastness will have a rating of about 4 or 5 on the Grey Change scale. Dyes that noticeably fade (going from red to pink, for example) will generally have a rating of about 3 on the scale. Dyes that are very prone to fading will have a rating of 1 or 2 on the scale.
For many manufacturers, it’s important to perform this test after multiple washes to simulate use over time. For example, a pair of dark blue jeans might appear to retain its color initially but fade to a much lighter blue after repeated washing. Quantifying those changes is critical to accurately assessing color fastness and implementing protocols to improve durability of color. Additionally, the scale can be used to quantify color change as the result of UV exposure, typically in an artificial aging environment.
The Grey Stain Scale Tests for Bleeding
While the Grey Change scale is used to detect color fading in a sample, the Grey Stain scale can be used to test textiles for bleeding and possible transfer staining. Even if a textile sample doesn’t fade in color, it’s possible that excess dye in the fabric will bleed onto other clothes during washing and result in staining. This happens often with direct red dyes in particular, especially if a piece of red fabric is washed alongside white fabrics.3 The Grey Stain scale can help you detect this problem shortly after you dye your fabric, allowing you to refine your dyeing process in response.
The Grey Stain scale works in much the same way as the Grey Change scale, analyzing the color of the sample against five standard color pairs. This time, however, you’ll measure the color of a piece of white test fabric, both before and after washing. After the white fabric is washed alongside your dyed fabric sample, you can use a spectrophotometer to analyze the color of the white fabric. Did it change in color? If the white fabric receives a rating of 5 on the Grey Stain scale, then it did not change in color, meaning that your colorful fabric sample didn’t bleed and stain the white fabric. If the white fabric received a rating of 1 or 2 on the scale, then significant color bleeding occurred, and you may have to refine the type or the amount of dye that you use in your textiles to prevent future bleeding.
How to Use the Grey Change and Grey Stain Scales
In order to use the Grey Change and Grey Stain color scales to analyze the durability of your textile dyes, you’ll need to operate your spectrophotometers in reflectance mode. Next, you can configure the display of your instrument so that it shows you the color scales. From here, you can simply follow the specific instructions for mounting your fabric samples onto the port of your spectrophotometer. As long as you are operating in standard reflectance mode and your sample is either backed by a white uncalibrated tile or made completely opaque, you can obtain an accurate Grey color scale reading for each sample. A number of HunterLab instruments s are capable of measuring samples using both types of Grey scales, as they are included in our innovative EasyMatch QC software. Because this software is already included with the spectrophotometers, you won’t have to perform a visual assessment of the Grey color scales yourself; this analysis is done for you, with a great degree of accuracy.
For more than 60 years, HunterLab has worked closely with the textile industry to find solutions to the varied challenges manufacturers face. Our spectrophotometers are designed to accurately detect the color of textile samples and include specialized software with the ability to make Grey Change and Grey Stain comparisons, offering manufacturers a fuller picture of their products. Using these tools and techniques, you can refine your textile dyeing process and create products that are as durable as they are beautiful. Contact us to find out more about our renowned instruments and which spectrophotometer may be best suited to your needs.
- “Why Does Ultraviolet Light Cause Colors to Fade?”, https://www.loc.gov/rr/scitech/mysteries/colors.html ↩
- “Textile Dyes and Color Fading”, http://textilesfr.co.uk/technical/textiles-dyes-colour-fading/ ↩
- “Why Are Red Dyed Items Susceptible to Bleeding?”, May 23, 2007, http://www.pburch.net/dyeing/dyeblog/C1605100905/E20070523145730/index.html ↩