What is the recommended dosage for silk dyeing and printing auxiliaries?

Because chemical concentrated formulas vary significantly by manufacturer, exact industrial dosages depend on the specific commercial product grade (solid vs. liquid dilutions) and the fabric's liquor ratio (the weight ratio of the fabric to the processing water).

However, standard industrial recipes operate within well-established baseline ranges. The tables below outline the recommended dosages for the core silk dyeing and printing auxiliaries, scaled to standard application units: grams per liter (g/L) for immersion dyeing baths and grams per kilogram (g/kg) for print pastes.

1. Immersion Dyeing Auxiliaries (Per Liter of Bath)

When liquid-to-fabric contact is continuous (such as in jet, overflow, or jig dyeing), auxiliaries are measured relative to the total volume of water.

Auxiliary Category Common Chemical Types Standard Industrial Dosage Purpose & Operational Note

Levelling Agents Amphoteric or non-ionic fatty amine ethoxylates 0.5 – 2.0 g/L Controls rapid initial dye exhaustion. High-affinity variants scale down to 0.5 g/L; repair/stripping formulas climb to 3.0 g/L.

Chelating / Sequestering Agents Amino-acid derivatives (GLDA/MGDA) or organophosphonates 0.5 – 1.5 g/L Binds to water-hardening ions (Ca²⁺, Mg²⁺) to protect silk's natural sheen.

pH Buffers / Regulators Ammonium sulfate, sodium acetate, mild organic acids 1.0 – 2.0 g/L Locks the bath into a safe, weakly acidic window (pH 4.5 – 6.0) to safeguard protein fibroin.

Anti-Crease / Lubricants High-molecular-weight polyacrylamide or specialty emulsions 1.0 – 3.0 g/L Minimizes mechanical friction-marks and deep rope creases in low liquor ratios.

Fixing Agents (Acid/Metal) Syntans, sulfonated aromatic condensation compounds 1.5 – 4.0% (on weight of fabric - owf) Applied in a fresh bath post-dyeing to securely block active fiber sites, stopping bleeding.

Fixing Agents (Reactive) Formaldehyde-free cationic polyquaterniums 2.0 – 5.0 g/L Applied via padding or a fresh finish bath at 40°C–50°C.

2. Printing Pastes (Per Kilogram of Paste Mixture)

In print paste preparation, auxiliaries are bundled directly into a concentrated thickener matrix to manage rheology (flow behavior) and structural boundary sharpness.

Auxiliary Category Primary Chemical Base Standard Industrial Dosage Preparation & Application Note

Thickeners (Stock) Sodium alginate, modified guar gum 40 – 60 g/kg (Dry powder) The dry powder is fully hydrated in water to form a 4% to 6% stock paste. This stock makes up roughly 60–70% of the final ready-to-print paste.

Penetration Co-Solvents Industrial Urea 100 – 150 g/kg Acts as a humectant (moisture retainer). Crucial during subsequent steaming steps to swell the silk fiber for dye diffusion.

Alkali / Fixation Donors Sodium bicarbonate (NaHCO₃) 20 – 30 g/kg Only required if printing with reactive dyes to induce the necessary fiber-reactive covalent bonds.

Resist Salts / Oxidants Sodium m-nitrobenzenesulfonate 10 – 15 g/kg Prevents reducing vapors from attacking sensitive dyes during long steaming cycles.

Soaping / Wash-Off Agents High-efficiency ethoxylated surfactants 1.0 – 3.0 g/kg Used during post-print rinsing baths to lock up and strip unfixed dye, avoiding backstaining on clean background profiles.

3. Post-Dyeing Finishing (Exhaust vs. Pad-Mangle Application)

When modifying the tactile feel (hand) of the silk in the final processing stage, the dosing method changes:

Exhaust Method (Long Bath): If applying a soft finish inside a dyeing machine, silicone emulsions or fatty acid amides are typically dosed at 1.0% to 3.0% owf (on weight of fabric).

Pad-Mangle Method (Continuous Continuous Line): If passing the silk web through a padding trough and squeeze rollers, the auxiliary concentration transitions back to liquor calculations, requiring 10 to 30 g/L inside the pad liquor setup before entering the stenter dryer.

Important Processing Rule: Silk has a lower specific surface area and a lower relative volume of amorphous zones compared to wool. Because of this, it saturates faster. Always check the exhaustion curve of your chosen dye class before increasing leveling or fixing agent quantities past these standard targets; over-dosing can inadvertently strip color yield or trigger sticky chemical spots.