How to Dye Nylon or Polyamide?
Nylon can be successfully dyed at boiling temperature (100°C) using acid dyes or disperse dyes, making it one of the most dye-friendly synthetic fibers available. The process requires acidic conditions (pH 4.5–6.5) for acid dyes, heat for proper fiber penetration, and Glauber’s salt as a leveling agent. With the right approach, nylon accepts a wide range of colors with good wash fastness.
There are several established methods for dyeing nylon, ranging from professional textile processing with acid dyes to home crafting techniques using all-purpose fabric dyes. The method you choose depends on your equipment, desired color fastness, and end-use requirements.
What Is Nylon?
Nylon is a synthetic polyamide fiber first developed by Wallace Carothers at DuPont in 1935. Two primary types dominate commercial production: Nylon 66 (melting point 265°C/509°F) and Nylon 6 (melting point 220°C/428°F). Nylon 66 exhibits a density of 1.15 g/cm³ and offers superior tensile strength, making it the preferred choice for demanding applications such as seatbelts, tire cords, and ballistic fabrics.
Where Do We Use Nylon?
Nylon’s versatility extends across textile and industrial applications. In apparel, it is used for blouses, hosiery, lingerie, underwear, swimwear, and raincoats. Home furnishing applications include curtains, bedspreads, carpets, and upholstery fabrics. Industrial uses encompass hoses, conveyor belts, seat belts, tire cord, racket strings, tents, sleeping bags, nets, and sewing threads.
Dyeing Nylon with Acid Dyes and Disperse Dyes
Nylon responds well to dyeing with acid dyes and disperse dyes. Both dye classes require heat to achieve proper fiber penetration and color development. Acid dyes bond to nylon through ionic attraction under acidic conditions (pH 4.5–6.5), while disperse dyes rely on thermal diffusion into the fiber structure.
When working with nylon blends containing other fibers such as nylon/Lycra combinations, caution is necessary. Lycra (elastane) is heat sensitive and begins to degrade at temperatures exceeding 180°C (356°F). The care label specifies temperature limits that should be followed to prevent unwanted deformation and loss of elastic recovery.
Teflon-coated nylon becomes water repellent and will not absorb water, making dyeing impossible.
Methods for Dyeing Nylon
Nylon can be dyed using several established processes. The method selected depends on available equipment, desired color fastness, and end-use requirements.
1. Nylon Dyeing with Acid Dyes
Acid dyes produce excellent wash fastness on nylon. Two groups of acid dyes are commonly used: Group A (weak acid/neutral liquor dyes) with pH 6.5–7.0 and superior leveling properties, and Group B (neutral liquor dyes) with faster initial dyeing rates but reduced migration.
- Consult the dye supplier for acid dye compatibility with nylon. Most acid dyes perform well with proper pH adjustment and heat.
- Dissolve the dye in water with Glauber’s salt (10–20% owf) following the recipe specifications.
- Add the nylon fabric to the dyebath at 40°C, then raise temperature at 1–2°C per minute to 98–100°C.
- Add acetic acid (pH 4.5–5.5) gradually and maintain for 30–60 minutes at boil.
- Cool the bath gradually to 70°C before rinsing. For enhanced wash fastness, apply back-tanning treatment with 2% owf tannic acid at 70°C for 20 minutes, followed by 1% owf tartar emetic at 70°C for 30 minutes.
2. Tie Dyeing Nylon
Tie dyeing on nylon produces unique creative designs using acid dyes. This technique is popular for fashion customization and small-batch production.
- Pre-soak the nylon fabric in a solution of water and citric acid (2–4 g/L) for 15–20 minutes.
- Bind or fold the fabric according to the desired pattern using rubber bands or string.
- Dissolve the acid dye in water at a concentration of 0.5–2% owf and heat to 70–80°C.
- Immerse the bound fabric in the heated dye solution and maintain at 70–80°C for 30–45 minutes.
- Allow to cool to room temperature before removing bindings.
- Rinse thoroughly with cold water and neutralise with a dilute sodium acetate solution.
3. Nylon Dyeing with Fiber Reactive Dyes
Fiber reactive dyes are typically used for cellulose fibers but can be applied to nylon using an acid dyeing recipe. When treated similarly to acid dyes, Procion MX and similar fiber reactive dyes produce colors on nylon, though paler shades result compared to silk.
Critical note: Maintaining alkaline pH with soda ash instead of acid will prevent proper dye uptake. Nylon fibers will either remain undyed or exhibit temporary color that washes out quickly when exposed to alkaline conditions.
4. Nylon Dyeing with All-Purpose and Multipurpose Dyes
Rit All-purpose dye and Dylon Multipurpose dye contain both direct dyes and leveling acid dyes. These products can dye nylon, though the direct dye component has no affinity for synthetic fibers and provides no benefit. The acid dye portion delivers the actual color.
These dyes are suitable for emergency situations when specialized textile dyes are unavailable. However, color fastness will be moderate at best, typically achieving only 2–3 on the grey scale for wash fastness.
5. Nylon Dyeing with Natural Dyes
Many natural dyes contain acidic components that enable them to bond with nylon. Cochineal produces an intense red shade with a slight brownish tone when mordanted with alum (potassium aluminum sulfate) at 15–20% owf. Turmeric generates a golden yellow shade on nylon with or without pre-mordanting.
Indigo dyes perform poorly on nylon. The tightly packed molecular structure of synthetic fibers offers insufficient pore space for indigo molecules to penetrate and become trapped after oxidation.
6. Nylon Dyeing in the Discharge Process
Hypochlorite (bleach) causes severe fiber damage and yellowing on nylon and must never be used for discharge printing or stripping. Sodium formaldehyde sulfoxylate (Rongalite) at 2–5 g/L provides safe discharge capability at 60–70°C with a pH of 9.0–10.5.
7. Nylon Dyeing with Disperse Dyes
Disperse dyes offer superior migration properties compared to acid dyes, ensuring even color distribution across nylon filaments with varying physical characteristics. This addresses the common issue of barre in acid-dyed nylon, where dye molecules fail to migrate evenly in fibers with inconsistent cross-sectional properties.
Acid dyes are limited to pale shades on nylon due to poor to moderate wash fastness ratings (typically 3–4 on the grey scale) in deep shades. Additionally, nitrogen oxide and ozone in atmospheric pollution cause nylon to fade. Disperse dye application is both economical and straightforward, requiring only 1–3% owf dye concentration at pH 4.5–5.5 (adjusted with acetic acid).
An innovative disperse dye application involves using rubber stamp pad ink, fabric paints, or specialized crayons applied to paper, then transferred to nylon fabric via ironing at 150–180°C. This method enables creative freedom for producing unique, vibrant designs suitable for both professionals and hobbyists.
Nylon Dyeing vs Polyester Dyeing
Nylon’s superior dyeability compared to polyester stems from fundamental differences in moisture absorption. Nylon absorbs 4% moisture at standard conditions (20°C, 65% relative humidity), while polyester absorbs only 0.4%. This moisture content allows water molecules to act as carriers, enabling dye molecules to diffuse into nylon fibers at 100°C.
In contrast, polyester requires temperatures of 130°C under high-pressure conditions or carrier chemicals to achieve adequate dye penetration. Without carriers, polyester dyeing at atmospheric pressure produces insufficient color yield and poor fastness.
Water acts as a natural carrier for dye molecules in nylon, eliminating the need for additional chemical carriers required in polyester dyeing.
This fundamental difference explains why nylon is the preferred synthetic fiber when ease of dyeing is a critical manufacturing consideration.
Quick Reference: Nylon Dyeing Parameters
| Dye Type | pH Range | Temperature | Key Additives | Wash Fastness |
|---|---|---|---|---|
| Acid Dyes (Group A) | 6.5–7.0 | 98–100°C | Glauber’s salt | Good to Excellent |
| Acid Dyes (Group B) | 4.5–5.5 | 98–100°C | Acetic acid | Good to Excellent |
| Disperse Dyes | 4.5–5.5 | 98–100°C | Acetic acid | Good |
| Fiber Reactive Dyes | 4.5–6.0 (acidic) | 80–100°C | Glauber’s salt, citric acid | Moderate |
| Natural Dyes (e.g. cochineal) | Acidic | 70–100°C | Mordant (alum) | Moderate to Good |
| All-Purpose Dyes | Neutral to slightly acidic | 85–100°C | Salt | Poor to Moderate |
Common Mistakes in Nylon Dyeing
- Using bleach for discharge: Hypochlorite (bleach) causes irreversible fiber damage and yellowing on nylon — never use it. Use sodium formaldehyde sulfoxylate (Rongalite) instead at pH 9.0–10.5.
- Exceeding temperature limits on blends: Lycra/elastane degrades above 180°C. Always check care labels and keep bath temperatures under this threshold.
- Alkaline conditions with fiber reactive dyes: Using soda ash (alkaline) instead of acid will prevent dye uptake entirely — nylon remains undyed or loses color after washing.
- Dyeing Teflon-coated nylon: Teflon coating makes nylon water-repellent and impossible to dye — this cannot be overcome with any dye type.
- Skipping the mordant with natural dyes: Without proper mordanting (e.g. alum for cochineal), natural dyes wash out quickly from nylon fibers.
- Indigo on nylon: Indigo molecules cannot penetrate the tightly packed structure of nylon — choose an alternative dye class for blue shades.
