How to Improve Wet and Dry Rubbing Fastness?

Improving wet and dry rubbing fastness (rubbing fastness) of textiles is a common quality issue, especially for dark fabrics (such as black and navy) and cellulosic fibers (such as cotton). This primarily involves dye selection, process optimization, and the use of finishing auxiliaries.

I. Root Cause Analysis

Understanding the causes of poor rubbing fastness is the first step in resolving the issue:

Loose dye: This is the primary cause. During wet rubbing, these loosely bound dyes transfer from the fiber to the test white cloth.

Surface finish: Fabrics with rough, hairy surfaces (such as canvas and brushed fabric) will remove more dye particles during rubbing.

Surface dye: Floating dye that has not been adequately washed out is the primary culprit for poor wet rubbing fastness.

Dye properties: Different dyes have different binding strengths to fibers. Although reactive dyes offer vibrant colors, wet rubbing fastness, especially for darker colors, has always been a challenge. Effect of finishing liquid: Some softeners may cause dye migration or form a sticky film on the fabric surface, which in turn reduces the rubbing fastness.

2. Solutions and specific measures

1. Pretreatment and dye selection (prevention is better than cure)

Ensure the quality of pretreatment: The fabric must be thoroughly scoured and evenly bleached, with good capillarity and whiteness. This allows the dye to penetrate evenly rather than floating on the surface.

Choose the right dye:

Select reactive dyes with good build-up and high fixation rate. Many dye manufacturers have a dye series specifically for high fastness requirements (such as Huntsman's Avitera series).

For dark varieties, consider using vat dyes or sulphur dyes. Their wet rubbing fastness is usually better than that of reactive dyes, but the cost and process are more complicated.

2. Dyeing process optimization (core link)

(1) Soaping: This is the most critical step to improve wet rubbing fastness. It is necessary to use sufficient hot water (above 90°C) and high-efficiency soap detergent to thoroughly wash away hydrolyzed dyes and floating colors. Increase the number of washes and the amount of water if necessary.

(2) Fixation: Use a fixing agent. Cationic fixing agents can combine with anionic dyes through charge interaction to form macromolecular compounds, thereby blocking water-soluble groups and preventing dye shedding.

Note: Some fixing agents may cause color change or reduce light fastness, so they need to be tested in advance.

(3) Rinsing: After soaping, rinse thoroughly with cold and warm water to ensure that all chemical additives and floating colors are removed.