Pore Diffusion
The velocity at which charged particles move through a liquid under the influence of an electric field or concentration gradient governs wet treatment speeds. A higher ionic mobility allows dye molecules and alkali ions to penetrate the microscopic pores of cotton fibers quickly. This rapid movement is essential for achieving deep and level coloration during short contact times.
Migration Speed
Small ions travel faster than large, complex dye molecules through the aqueous channels of the textile substrate. In typical dyeing processes, the ionic mobility of sodium and hydroxyl ions is much higher than that of the bulky reactive dye anions. This difference means the alkali always reaches the inner core of the fiber before the dye can fix, preventing ring-dyeing.
Temperature Influence
Thermal energy reduces water viscosity and increases the kinetic energy of dissolved ions.
Charge Effect
Electrostatic forces between the fiber surface and the dissolved ions either accelerate or retard the penetration rate. High ionic mobility of the neutralizing salt ions shields the negative charge of the cellulose, allowing the dye molecules to diffuse without repelling each other. Maintaining the correct ionic strength in the bath ensures that this diffusion occurs uniformly, preventing surface-only dyeing and improving the color fastness of the finished garment.
