Continuous Pad Dyeing Basics for Cellulosic Blend Fabrics
Continuous pad dyeing of cellulosic blends requires precise wet pickup control, anti-migrant chemistry, and strict thermal limits to prevent shade listing.
Durometer
Measuring Instrument
Portable hand-held gauges determine the hardness of rubber squeeze rolls and wound yarn packages by measuring the resistance of the material to a spring-loaded indentor point. A durometer provides a numerical score that indicates how easily the surface deforms under localized pressure. This measurement is recorded during routine equipment inspections in dyeing and finishing mills.
Hardness Value
The instrument operates by pressing a calibrated metal pin into the surface of the textile roll or package. A low score on the Shore A scale indicates a soft rubber roll that yields under load, while a higher value represents a rigid roll that applies intensive, narrow nip pressure. In yarn package testing, a consistent durometer reading across the package height ensures that dye liquor will flow uniformly through the wound yarn.
This consistency prevents the channeling of dye.
Dyeing Application
In continuous pad dyeing, the hardness of the padder roll determines the pickup volume and the penetration of the dye liquor. Technicians use a durometer to verify that the roll has not hardened due to age or chemical exposure. If the rubber is too hard, it decreases the contact area in the nip, reducing the time the fabric spends under pressure and causing poor dye penetration.
This inspection is carried out before every major production run to guarantee uniform pickup.
Maintenance Standard
Rubber rollers degrade over time from chemical exposure and heat, which changes their hardness profile. Periodic checks ensure that the roller’s hardness remains within the specified range for the fabric type. If the hardness deviates from the standard, the roller must be ground or replaced.