How to Dye Nylon (Polyamide): Acid Dye Method, Parameters and Tips

Nylon is one of the easiest synthetic fibers to dye. It takes acid dyes in a hot, acidified water bath: about 85–95°C at home and 98–100°C in an industrial dyehouse, with the bath held at roughly pH 4–6. Disperse dyes also work, mainly for pale shades and transfer printing. With acid dye, a stainless steel pot, a thermometer and white vinegar, home dyers can get bright, even color on nylon fabric, yarn and garments.

What Is Nylon?

Nylon is a synthetic polyamide fiber first developed by Wallace Carothers at DuPont in 1935. Two types dominate commercial production: Nylon 66 (melting point 265°C/509°F) and Nylon 6 (melting point 220°C/428°F). Nylon 66 has a density of about 1.14 g/cm³ and high tensile strength, which makes it the usual choice for seatbelts, tire cords and ballistic fabrics.

In apparel, nylon goes into hosiery, lingerie, swimwear, activewear, blouses and raincoats. Home uses include carpets, curtains, bedspreads and upholstery. Industrial uses include hoses, conveyor belts, tire cord, racket strings, tents, sleeping bags, nets and sewing thread.

Dyeing Nylon with Acid Dyes and Disperse Dyes

Nylon can be dyed with two completely different dye classes: acid dyes and disperse dyes. Both need heat to get the dye into the fiber.

Acid dyes bond to nylon through ionic (electrostatic) attraction. In an acidic bath, nylon’s amino end groups pick up a proton and become positively charged (–NH₃⁺), and the dye’s negatively charged sulfonate groups (–SO₃⁻) are drawn to them. That is the same mechanism acid dyes use on wool and silk, which is why one acid dye works on all three fibers. Because nylon has a limited number of amino end groups, it has a saturation limit for acid dye, and very deep shades need dyes chosen for nylon.

Disperse dyes, the same class used on polyester, are small, nonionic molecules that diffuse into nylon by heat alone. They cover physical irregularities in the yarn well, so they hide barré (stripes caused by variations between filaments) better than acid dyes. Their weakness on nylon is wet fastness: acid dyes are more washfast on nylon than disperse dyes, so disperse dyes are mostly used for pale shades, hosiery and transfer printing.

Industrial dyers group acid dyes by how they behave in the bath. Levelling acid dyes migrate well and give even color but have lower wet fastness, especially in deep shades. Milling acid dyes are applied around pH 4–6 and balance levelness with fastness. Super-milling and metal-complex dyes are applied close to neutral (about pH 6–7), level poorly, and give the best wash fastness. Home acid dyes sold for wool, silk and nylon are usually a mix of these, applied at pH 4–6.

Water-repellent, stain-resistant or Teflon-coated nylon repels the dye bath, and the finish has to come off before the fabric will dye evenly.

Materials and Equipment Needed

A kitchen covers most of what you need. Use a stainless steel or enamel pot, never aluminum, which reacts with the acid. Once a pot or spoon has been used for dye it is no longer food safe, so keep a set of tools for dyeing only.

How Much Dye to Use

Dye is measured as a percentage of the dry fabric’s weight, known as owf (on weight of fabric). For 100 g of fabric, 1% owf means 1 g of dye powder. Weigh the fabric dry before you start.

Step-by-Step: How to Dye Nylon with Acid Dye

This is the stovetop immersion method for solid colors. Most failures in home nylon dyeing come from skipping the acid or letting the temperature drift, so keep the thermometer in the pot.

Step 1: Prepare the Fabric

Weigh the dry fabric so you can calculate the dye. Then wash it in warm water with a mild detergent to strip sizing, finishes and oils from manufacturing or handling. Rinse, and squeeze out the excess water gently instead of wringing, which can stretch the fibers. Keep the fabric wet. Dry nylon takes dye unevenly and gives patchy, streaked color that you cannot fix in the rinse.

Step 2: Set Up the Dye Bath

Fill the pot with enough water for the fabric to move freely. A water-to-fabric ratio of about 20:1 by weight works well. With too little water the dye cannot spread evenly, and with far too much the color comes out weaker. Heat the water to 40–50°C.

Meanwhile, dissolve the weighed dye powder in a small container of hot water and stir until no grains remain. Undissolved particles leave dark specks on the finished fabric. Pour the dissolved dye into the pot and stir well.

Step 3: Add the Fabric and Heat to 85–95°C

Add the wet fabric, fully submerged and loose, never bunched. Folded or stacked areas take less dye and end up as pale streaks. Raise the temperature slowly to 85–95°C (185–200°F), just below boiling: you should see steam and a few small bubbles at the edges, not a rolling boil. Stir every few minutes as it heats.

Step 4: Add Acid and Hold for 30–60 Minutes

Once the bath is hot, add about 60 ml (1/4 cup) of white vinegar per 450 g (1 lb) of dry fabric, or 1 tablespoon of citric acid dissolved in warm water. Pour it beside the fabric, not onto it, to avoid dark spots. Check with a pH strip that the bath reads pH 4–6. Without enough acid, the dye does not bond to the nylon and washes out. Adding the acid after the fabric has heated in the dye gives the color time to spread evenly before it fixes.

Hold the temperature at 85–95°C and stir gently every 5–10 minutes. Allow about 30 minutes for light shades and 45–60 minutes for medium to dark shades. The bath gets lighter as the dye moves into the fiber. That is exhaustion, and a nearly clear bath means the fabric has taken up most of the dye.

Step 5: Cool, Rinse and Dry

Turn off the heat and let the bath cool to about 50–60°C before lifting the fabric out with gloves. Rinse first in warm water, then in progressively cooler water, until the water runs clear. Colored runoff is unfixed dye that would otherwise bleed in the wash. Finish with a wash in mild detergent, rinse again, and lay flat or hang to dry.

Industrial Acid Dyeing of Nylon

Mills use the same chemistry with tighter control, and dye suppliers can say which acid dyes suit nylon best. A typical exhaust recipe:

1. Set the bath at about 40°C with the dye, Glauber’s salt (sodium sulfate) as a levelling aid, and any levelling agent, then add the nylon.
2. Adjust to pH 4.5–5.5 with acetic acid, or to the pH the dye class needs.
3. Raise the temperature at about 1–2°C per minute to 98–100°C.
4. Hold at the boil for 45–60 minutes.
5. Cool gradually to about 70°C before rinsing, to avoid creasing.
6. For deep shades that need better wet fastness, apply a back-tanning aftertreatment: tannic acid followed by tartar emetic (potassium antimony tartrate) in the classic process, or a synthetic tanning agent (syntan) in most modern dyehouses.

Nylon 6 has more affinity for acid dyes than nylon 66, so dyers often start a nylon 6 bath at a slightly higher pH and lower it as the temperature rises to control the strike rate.

Also Read:

• Acid Dye for Wool and Silk: The Complete Beginner’s Guide
• How to Dye Polyester at Home: Disperse Dye Technique
• Can You Dye Nylon Rope

Other Methods for Dyeing Nylon

Tie Dyeing Nylon

Acid dyes also work for tie-dye on nylon. Soak the fabric in water with vinegar, bind it with rubber bands or string, then apply the dissolved acid dye directly to the sections. Because acid dye needs heat to fix, the bundle then has to be steamed or microwaved (wrapped, in a dish kept for dyeing only) before rinsing and untying.

Fiber Reactive Dyes

Most fiber reactive dyes, such as Procion MX, cannot react with nylon the way they react with cotton. Used in an acid dye recipe with vinegar and heat, they behave as acid dyes and do color nylon, though usually to a paler shade than silk dyed the same way. Do not use the cotton recipe with soda ash. In an alkaline bath the dye has no attraction to nylon, and the fabric stays undyed or the color washes out.

All-Purpose and Multipurpose Dyes

Rit All-Purpose and Dylon Multipurpose dyes contain two dyes mixed together: a direct dye for cotton and a levelling acid dye for wool and nylon. Only the acid dye part colors nylon, so the direct dye is wasted and the final color is harder to predict. They are fine when nothing else is available, but pure acid dye gives better color and fastness.

Natural Dyes

Many natural dyes behave as acid dyes and work on nylon when heated in a bath with vinegar or citric acid. Cochineal gives nylon an intense red with a slightly brownish tone, with or without an alum mordant. Turmeric gives a medium golden yellow, with or without alum, though it fades in light. Indigo is reported to perform poorly on nylon and other synthetics, which lack the internal spaces where the reduced dye can penetrate and become trapped on oxidation.

Disperse Dyes and Heat Transfer

Disperse dyes can be used by immersion at 98–100°C and pH 4.5–5.5, typically at 1–3% owf, but they are less washfast than acid dyes on nylon. Their more useful home application is transfer printing: draw or stamp a design on paper with disperse dye inks, paints or crayons, then iron it onto the nylon at about 150–180°C.

Discharge (Color Removal)

Never use hypochlorite (household chlorine bleach) to discharge or strip color from nylon. Like wool and silk, the fiber itself is severely damaged. Sodium formaldehyde sulfoxylate (Rongalite, sold to hand dyers as Formusol) is the usual discharge agent for dyed nylon. Ask your dye supplier which acid dyes discharge cleanly, because some resist it.

Nylon Dyeing vs Polyester Dyeing

Nylon is far easier to dye than polyester, and moisture absorption is a large part of the reason. Nylon absorbs about 4% moisture at standard conditions (20°C, 65% relative humidity), while polyester absorbs only about 0.4%. Water swells nylon enough for dye molecules to diffuse in at 100°C, and nylon also carries the amino groups that attract acid dyes.

Polyester has neither advantage. It needs disperse dyes at about 130°C under pressure, or chemical carriers at the boil, to get adequate dye penetration. Without them, polyester dyed at atmospheric pressure gives weak color and poor fastness.

Quick Reference: Nylon Dyeing Parameters

Fiber Compatibility: Which Fabrics Can Be Acid Dyed?

Check the fiber content first. The acid dye bath that works on nylon does little for several common fibers.

Nylon-wool and nylon-silk blends take the acid dye bath on both fibers, although the shade can differ slightly between them. A color mixed from two or more dyes may also come out a different hue on nylon than on wool or silk. Blends with cotton, polyester or acrylic dye unevenly, because those fibers need dye classes that do not work in the same bath.

Common Mistakes and Troubleshooting

Nearly every problem in home nylon dyeing traces back to preparation, temperature or pH.

• Dyeing only adds color. You can move a fabric darker or toward a related hue, but you cannot dye it lighter, and an existing color mixes with the new one.
• For a deeper shade, a second dyeing session after the fabric has dried often gives more saturated color than doubling the dye in one session.
• Nylon-elastane (Lycra) blends are heat sensitive. Follow the care label and avoid long, hard boiling, which can reduce stretch recovery.

Frequently Asked Questions

Can you dye nylon fabric at home without a professional setup?

Yes. Home acid dyeing of nylon needs a stainless steel or enamel pot, a thermometer, white vinegar or citric acid, and acid dye from a craft supplier. Use gloves and good ventilation, and keep the pot and tools for dyeing only, since they are no longer food safe.

What temperature is needed to dye nylon?

At home, hold the acidified bath at 85–95°C, just below boiling, for 30–60 minutes. Industrial dyehouses run acid dyes on nylon at 98–100°C. Below about 80°C the dye exhausts poorly and the color comes out weak.

What pH should a nylon dye bath be?

For home dyeing, pH 4–6 works for most acid dyes. In industry the pH depends on the dye class: levelling acid dyes run in more acidic baths, milling dyes around pH 4–6, and super-milling and metal-complex dyes closer to neutral, about pH 6–7.

Can you dye nylon that is blended with cotton or polyester?

Acid dye colors only the nylon. In a nylon-cotton blend the cotton stays pale unless you dye it separately, for example with a fiber reactive dye and soda ash first, then acid dye with heat and vinegar for the nylon. In a nylon-polyester blend the polyester stays undyed, which gives a heathered look.

How wash-fast is acid dye on nylon?

Good, when the dye is applied with enough heat and acid and rinsed well. Milling and metal-complex acid dyes give better wet fastness than levelling acid dyes, especially in deep shades, and mills can improve it further with a back-tanning aftertreatment. Acid dyes are more washfast on nylon than disperse dyes.

Can you use Rit or other all-purpose dye on nylon?

Yes. All-purpose dyes such as Rit All-Purpose and Dylon Multipurpose mix a direct dye for cotton with a levelling acid dye that colors nylon. Only the acid dye part works on nylon, so pure acid dye gives more predictable color and better fastness.

References

• Clark, M. (ed.) (2011). Handbook of Textile and Industrial Dyeing, Volume 2: Applications of Dyes. Woodhead Publishing. Chapter 2, “Dyeing of synthetic fibres”.
• ISO 105-C06:2010. Textiles, Tests for colour fastness, Part C06: Colour fastness to domestic and commercial laundering. International Organization for Standardization.
• Burch, P.E. How can I dye nylon or polyamide? All About Hand Dyeing.
• Dharma Trading Co. Jacquard Acid Dye Instructions.