Standard Salt Dosing Schedules for Reactive Dyeing Heavy Cotton Canvas
Progressive exponential salt dosing prevents surface strike spikes and forces reactive dye penetration into heavy cotton duck yarn cores.
Glauber Salt
Inorganic Electrolyte
Hydrated sodium sulfate decahydrate crystals find widespread application as promoting electrolytes in cellulosic dyehouses. Known historically and commercially as Glauber salt, this inorganic compound dissociates in aqueous dyebaths to provide positive sodium cations. These cations neutralize the negative electrical zeta potential naturally present on cotton fibres immersed in water.
Reducing the negative surface charge lowers electrical repulsion, enabling anionic direct and reactive dyes to approach and adsorb onto fibre polymer chains.
Dyebath Action
Dye recipes require between twenty and one hundred grams per litre of dissolved salt depending on liquor ratio and dye substantivity. Glauber salt dissolves endothermically in warm liquor, causing brief temperature drops if added rapidly in bulk quantities without pre-dissolution. Its neutral pH profile prevents premature fixation reactions during exhaust migration periods, preserving level shade development across large textile lots.
Purity Verification
Testing protocols verify iron, calcium and magnesium impurity levels to prevent catalytic degradation of bleached goods or premature dye precipitation. Technical grades must contain less than twenty parts per million of dissolved iron to avoid shade dulling in light pastel reactive shades.
Process Limitation
Dyebaths substitute anhydrous sodium sulfate or sodium chloride when automatic liquid dosing systems or storage space limitations disfavor bulky crystalline decahydrate materials. Glauber salt provides no salt promotion effect in synthetic disperse dyeing of hydrophobic polyester fabrics.