Reduction Clearing
Reduction clearing is a post-treatment in which polyester and similar fabrics dyed mainly with disperse dyes are washed in a solution containing a reducing agent to remove excess dye remaining on the fiber surface and improve fastness.
Contents6 sections
Definition and Overview
Reduction clearing is one of the washing processes carried out on fabric after dyeing. Using a reducing agent and an alkaline agent, it removes unfixed dye remaining on the fiber surface and between fibers, with the aim of reducing color transfer and staining on the finished product.
It is a treatment often performed for polyester dyeing with disperse dyes. Unlike the dyeing process, which fixes dye inside the fibers, this is a process that removes excess dye after dyeing to improve quality.
Features
Fabric that has been properly reduction cleared is less likely to allow excess dye on the surface to transfer to other fabrics through washing or friction. In particular, for dark colors, it is an important post-treatment related to the stability of washing fastness and rubbing fastness.
This treatment is mainly for improving color fastness and is not a process that directly adds softness, luster, or water absorbency. Changes in hand feel and appearance vary depending on the material, dye, washing conditions, and subsequent softening treatments.
Main Applications
It is widely used from dark to light shades when dyeing polyester woven fabrics and knits with disperse dyes. It is especially important for quality control in apparel fabrics expected to undergo washing and friction, such as shirts, blouses, pants, skirts, jackets, sportswear, and uniforms.
Although it is not a treatment limited to a specific season, checking the fastness according to the intended use is important for spring and summer apparel, sportswear, and workwear, which are often exposed to sweat, friction, and repeated washing.
Selection and Handling Precautions
When selecting fabric, do not judge quality based only on whether reduction clearing has been performed; confirm the washing fastness, rubbing fastness, and perspiration fastness required for the intended use through test results. In dark colors, color combinations, and combinations with light colors, it is important to evaluate color transfer during the planning stage.
Even fabric that has undergone reduction clearing cannot completely prevent fading or migration depending on washing conditions and friction strength. Confirm the finished product state before mass production, including whether garment washing is performed, combinations with accessories, and whether printing or coating is present.
Since moisture and heat are applied during processing, check shrinkage and dimensional changes against the fabric specifications. In sewing, also pay attention to migration caused by dark-light color combinations and staining of white sewing thread or tapes, and perform prototypes and washing tests as needed.
Differences from Similar Terms
Soaping is a broad washing treatment that removes excess dye and auxiliaries after dyeing. Reduction clearing, among these, refers to a treatment that uses a reducing agent to reduce and decompose disperse dyes and make them easier to remove.
Fixing treatment is carried out to fix dye and improve fastness. Reduction clearing is a post-treatment for removing excess dye, and its purpose and action are different.
Frequently Asked Questions
Does reduction clearing eliminate color fading?
Reduction clearing is a treatment that removes excess dye remaining on the surface and reduces the risk of color transfer and staining. However, it does not completely eliminate color fading. Results vary depending on the material, color, dye, and washing conditions, so confirmation by fastness tests appropriate to the intended use is necessary.
Is reduction clearing also performed on cotton and wool?
Reduction clearing is often performed on polyester and similar materials dyed with disperse dyes. Cotton and wool use different dyes and dyeing methods, so even for the same purpose, different washing conditions or post-treatments are generally selected. It is necessary to confirm the combination of material and dye.
