Chemical Threshold
Maximum allowable concentration of alkali remaining in yarn or fabric after wet finishing defines the safety margin for subsequent textile operations. This parameter, known as residual alkalinity tolerance, must be tightly controlled during the washing stages to protect the material from degradation. It ensures that the fabric is safe for consumer use and subsequent processing.
Fabric Degradation
Leftover sodium hydroxide on the fibers can cause yellowing and localized fiber damage during drying or storage. If the fabric exceeds the residual alkalinity tolerance, the high pH can also interfere with the reactive dyes used in the printing stage. This interference leads to patchy color development and poor wash-fastness.
Storing alkaline fabric can slowly hydrolyze cellulose fibers, reducing tensile strength.
Measurement Protocol
Technicians measure the pH of the extracted water from the fabric or perform a micro-titration to check the alkali level. When testing against the residual alkalinity tolerance, a standard test method involves boiling a fabric sample in distilled water and measuring the resulting pH. This value should remain within a range of six to eight.
Consistent monitoring at this stage prevents customer returns.
Quality Standard
Strict compliance with these limits is required by international textile safety standards. By maintaining the residual alkalinity tolerance, mills prevent fabric discoloration and damage. This quality control measure secures the product’s longevity.
