Acid dyes are the workhorse of the leather dyeing industry. Whether you are dyeing shoe uppers, garment leather, automotive upholstery, or leather accessories, acid dyes deliver the penetration, shade depth, and fastness that leather manufacturers require.
This guide covers everything your production team needs to know — from why acid dyes work on leather, to which grades perform best for specific applications.
Why Acid Dyes for Leather?
Leather is a protein substrate — chemically similar to wool and silk. Its structure contains amino groups (-NH₂) and carboxyl groups (-COOH) that interact with the anionic (negatively charged) molecules of acid dyes under acidic conditions.
When the dye bath is acidified (typically with formic acid), the leather's amino groups become protonated and attract the anionic dye molecules. The dye penetrates through the fibre cross-section and bonds ionically with the substrate — creating an even, penetrating colour that is resistant to rubbing and washing.
No other dye class gives this combination of penetration depth, levelness, shade range, and rub fastness on leather. This is why acid dyes dominate leather dyeing globally.
Application Conditions for Leather
| Parameter | Typical Range | Notes |
|---|---|---|
| pH | 3.5–4.5 | Use formic acid to achieve pH; lower pH = better fixation |
| Temperature | 40–60°C | Lower than textile acid dyeing; high temp can damage leather |
| Dye Bath Ratio | 1:5 to 1:10 (leather:water) | Shorter bath gives deeper shade |
| Time | 45–90 minutes | Depends on leather type and shade depth |
| Acid Used | Formic acid | Acetic acid also used; formic gives better penetration |
| After-Treatment | Fat-liquoring | Restores leather softness after dyeing; done after dye fixation |
Key Grades for Leather Dyeing
From Yobai Industries's acid dye range, the following grades are most widely used in leather applications:
Acid Black — (Acid Black 1, 52, 210, 234)
The most important colour in leather dyeing. Acid Black 1 is the industry standard for deep black leather goods. Multiple grades are available for different fastness and shade requirements. View Acid Black 1 specs →
Acid Brown — (Acid Brown 75, 83, 98, 188 and more)
22 brown grades covering everything from light tan to deep chocolate. Acid Brown 75 (ACID BROWN TN) is the most widely used grade for shoe upper leather and automotive upholstery. View Acid Brown 75 specs →
Acid Red — (Acid Red 114, 131, 97 and more)
Bright red shades for leather goods, handbags, and garment leather. Acid Red 114 is the standard red in leather trichromatic systems. View Acid Red 114 specs →
Acid Blue — (Acid Blue 113, 158, 193 and more)
Medium to bright blue shades for leather accessories, garments, and upholstery. Good levelness on uneven leather surfaces. View Acid Blue 158 specs →
Fastness on Leather
Fastness requirements for leather are different from textiles. The key fastness properties for leather are:
- Rub fastness (dry and wet): The most important fastness property for leather. Customers wearing or using leather goods will rub the surface — colour must not transfer to clothing or skin. Acid dyes generally offer 3–4/5 rub fastness, improvable with proper fixation.
- Light fastness: Especially important for automotive upholstery and outdoor leather goods. Select higher lightfast grades for these applications.
- Perspiration fastness: Important for shoe linings and garment leather in contact with skin.
Leather Types and Dye Selection
Vegetable-Tanned Leather
Vegetable-tanned leather has a more complex fibre structure and lower dye uptake than chrome-tanned leather. Acid dyes penetrate less easily, so slightly higher dye concentrations or longer dyeing times may be needed. Choose dyes with good affinity and penetrating properties.
Chrome-Tanned Leather
Chrome-tanned leather is the most common substrate for acid dyeing. It has excellent dye uptake and produces bright, even shades with standard acid dye grades. The chromium in the leather can also improve the light fastness of certain acid dyes.
Combination-Tanned Leather
Combination-tanned (retanned) leathers behave somewhere between vegetable and chrome-tanned leather. Testing is advisable before committing to production quantities.
Ordering from Yobai Industries
Yobai Industries maintains a full range of acid dyes suitable for leather dyeing — including blacks, browns, reds, blues, greens, oranges, and violets. All grades are batch-tested for colour strength and solubility before dispatch.
- MOQ: 10 kg (sample orders of 1–5 kg available within 24 hours)
- Packaging: 1 kg · 5 kg · 10 kg · 25 kg · 50 kg · Custom
- Documentation: TDS and GST invoice with every order
- Export: India + Worldwide