Sweat Fastness
Sweat fastness is a fastness rating that evaluates how little a textile’s color changes and how little it transfers to other textiles when affected by moisture, salts, and other components contained in sweat.
Contents5 sections
Definition and Overview
Sweat fastness is a quality item that checks color change and staining on attached white cloth after a textile is brought into contact with a test solution that simulates sweat and treated under specified conditions. It is important because it evaluates both color change caused by sweat and color transfer.
In testing, evaluation is generally performed using acidic and alkaline sweat solutions. For clothing worn close to the skin, testing assumes contact between textiles, or between a textile and lining, during sweating while worn.
Features and Impact on Products
Sweat fastness does not directly indicate the thickness, stretch, absorbency, breathability, or hand of a textile. It is an evaluation related to color durability, mainly affected by dye, hue, dyeing method, and aftertreatment.
If the value is not sufficient, dark textiles exposed to sweat or moisture may look dull, or color may transfer to light-colored fabrics, linings, underwear, and the like. The impact on appearance is especially significant in designs that combine dark and light colors.
- Color change: the textile’s own color tone changes due to the action of sweat.
- Staining: dye transfers to another textile in contact with it.
- Sweat fastness is a separate evaluation from absorbency, which indicates how easily sweat is absorbed.
Main Applications
It is checked for clothing worn close to the skin and prone to sweating, such as T-shirts, shirts, blouses, innerwear, sportswear, and uniforms. It must be considered not only for spring and summer items, but also for autumn and winter items that can become stuffy when layered, as well as clothing worn during exercise or work.
Areas such as the underarms, neck opening, back, and waist are especially affected by sweat. For specifications where different colors or materials come into contact, such as color-blocking, prints, embroidery, tape, and lining, confirmation using combinations close to the finished product is useful.
Selection and Handling Notes
When selecting a textile, check the test results for the sweat fastness required for the application, separating color change from staining. Because results may differ depending on color, material, processing, and lot, it is important to test the adopted color in the actual combination.
Sweat fastness differs in test conditions from color fading due to washing and color transfer due to friction in dry or wet conditions. Assuming wearing situations where sweat, washing, and friction overlap, also check washing fastness and rubbing fastness.
It is not a direct indicator for judging shrinkage or sewability. However, when sewing together dark and light textiles or accessories, check whether wet conditions after sewing cause transfer to the contact area, and conduct advance testing or washing tests if necessary.
Frequently Asked Questions
What is the difference between sweat fastness and washing fastness?
Sweat fastness evaluates color change and staining caused by a sweat-like solution, while washing fastness evaluates color durability against water, detergent, mechanical action, and the like during washing. Even if one is good, the other is not necessarily at the same level, so both should be checked according to the application.
If sweat fastness is good, will color transfer to white clothing not occur?
Even if sweat fastness is good, color transfer due to other factors such as wet rubbing, washing, or long periods of close contact may still occur. For specifications that combine dark and light items, it is important to check rubbing fastness and washing fastness in addition to sweat fastness, and to carry out advance testing on the product.
