Sulphur Red LGF C.I. Sulphur Red 14 CAS No.81209-07-6

Sulphur Red LGF (C.I. Sulphur Red 14) is a widely used sulfur dye for dyeing cotton, viscose, linen, and their blended fabrics. CAS No.81209-07-6.

Appearance & Properties

It comes as a red powder, insoluble in water but soluble in reducing agents such as sodium sulfide (Na₂S). After dyeing, the material is re-oxidized to restore the original insoluble color on the fiber.

Application Method

The dye is reduced into its leuco (water-soluble) form in an alkaline reducing bath. Common reducing agents include sodium sulfide or sodium hydrosulfite. After the fiber absorbs the dye, the material is exposed to air or treated with oxidizing agents like hydrogen peroxide or sodium dichromate to fix the color. This method is cost-effective and suitable for exhaust or continuous dyeing processes.

Performance & Fastness

Sulphur Red LGF provides deep red shades with good build-up properties. It offers excellent light fastness (typically rating 6–7), very good wash fastness (4–5), and decent rub fastness, though shades may darken slightly over time. It is not suitable for bright scarlet or pink tones but works well for medium to deep reddish hues.

Applications

· Workwear, uniforms, and heavy-duty fabrics

· Denim yarns (including warp dyeing)

· Industrial textiles where cost and wash durability matter

Limitations

· Chlorine fastness is low (not suitable for frequent bleaching)

· Heavy metals may be present; effluent treatment required

· Some dark shades may undergo "bronzing" (surface metallic sheen)

Eco-Note

Modern formulations often replace sodium sulfide with eco-friendly reducing systems (e.g., glucose-alkali) to reduce sulfide waste. Even so, sulfur dyes remain less eco-friendly than reactive dyes but are preferred for low-cost, high-washfastness applications.

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