We earn a commission if you buy through links on this page, at no extra cost to you. Product suggestions are based on dye chemistry, manufacturer instructions and my experience dyeing nylon in industry; links are Amazon affiliate links.
Quick answer
The nylon fabric dyeing process uses acid dyes in an acidic bath (about pH 4–6), heated slowly from 40°C to around 98°C and held for 45–60 minutes. In acid, nylon's amine end groups turn positive and bond ionically with the negative dye. Scour first, add a levelling agent, then soap and apply a fixing agent for dark shades.
Why nylon takes acid dyes
Nylon (polyamide 6 or 6.6) has amine end groups (–NH₂) at the ends of its polymer chains. In an acid bath they pick up a hydrogen ion and become positive (–NH₃⁺). Acid dyes are anionic: they carry negatively charged sulphonate groups. The negative dye is pulled onto the positive site and held by an ionic bond, helped by van der Waals forces and hydrogen bonding.
Two things follow. pH controls the speed: the lower the pH, the more positive sites and the faster the dye goes on. And nylon has far fewer sites than wool, so it reaches saturation earlier, which makes very deep shades harder and lets small yarn-lot differences show as stripes. Wet nylon also softens at a low temperature, so dye can strike very fast mid-heating.
Expert tip from Kamrul Islam
Salt does not push acid dye onto nylon. Sulphate ions compete with the dye for the positive sites, so Glauber's salt or ammonium sulphate acts as a retarder. Add it only if you need to slow a fast-striking dye.
What type of dye is needed for nylon?
Acid dyes are the standard class for nylon sportswear, swimwear, lingerie and hosiery. Within that class, the choice depends on how level the shade must be and how much wash and light fastness you need.
| Dye type | Typical dyeing pH | Levelling | Wet fastness | Best use on nylon |
|---|---|---|---|---|
| Levelling (equalising) acid | about 3–5 | Excellent | Low | Pale and bright shades, hosiery |
| Half-milling acid | about 4–6 | Good | Moderate | Medium shades, general apparel |
| Milling acid | about 5–7 | Fair; needs care | Very good | Medium to dark shades, activewear |
| 1:2 metal-complex acid | about 5–7 | Fair | Very good, plus high light fastness | Car interiors, swimwear, dark shades |
| Disperse | Neutral to slightly acid | Very good; covers barré | Limited | Light shades only |
| Reactive dyes for wool | Weakly acid | Fair | Very good | Some dark shades needing top wash fastness |
pH ranges are typical for each dye type. Always follow the dye maker's pattern card for the exact recipe.
Cotton-reactive dyes, direct dyes and household cold-water dyes do not bond to nylon. If your garment is a cotton-nylon mix, each fibre needs its own dye; see my cotton nylon blend dyeing process.
Nylon dyeing process step by step (industrial)
This is the route I use for 100% nylon and nylon-elastane knits in exhaust machines. Doses and times are typical and change with shade depth and dye selection.
- Pre-treatment (scour). Load at about 80°C and scour with detergent and a mild alkali at around 95°C to remove knitting oils and spin finish. Rinse and neutralise back to pH 7 so the next bath starts clean.
- Heat setting (nylon-elastane). Heat-set before dyeing to fix width and stop creasing. Keep the stenter at or below 180°C; elastane is damaged at 190–200°C.
- Set the bath. At 40°C add the levelling agent and acid donor (or acetic acid buffer) over 5 minutes and run 10 minutes so the chemicals reach every part of the fabric.
- Add the dye. Dissolve dyes in a side tank with water at 90°C for 15 minutes, then dose over about 20 minutes and run 10 minutes.
- Temperature ramp. Raise 40→50°C at 1°C/min, then 50→98°C at 0.5°C/min. A 10-minute hold at 70°C helps levelness in the critical 60–90°C band where dye strikes hardest.
- Hold at 98°C. Run about 45–60 minutes so dye diffuses into the fibre and migrates for a level shade.
- Cool and check shade. Cool to about 75°C at 1°C/min, take a sample and match against the standard before dropping the bath.
- Soaping. Wash off with a soaping agent (about 2 g/L) at 80°C for 10 minutes, up to 15 minutes for dark shades, to remove loose dye.
- Fixing. For medium and dark shades, apply a fixing agent (syntan type) at pH 5–5.5. It blocks the dye in the fibre and lifts wet fastness.
- Soften and finish. Softener at pH 5–5.5 in the last bath, then dry and finish on the stenter at around 110°C to avoid a harsh hand.
From my dyeing recipes
Instead of dumping acetic acid at the start, I use an acid donor that releases acid as the bath heats. The pH slides down during the run: light shades 8.0 → 5.0, medium 7.5 → 4.5, deep 7.0 → 4.1. Dye goes on slowly at first and exhausts fully at the end, which gives a far more level result than a fixed low pH. At a 1:8 liquor ratio with 600 L of liquor, a medium navy needs 300 g of donor and a pale grey 150 g.
Nylon dyeing temperature and pH range: typical recipe
| Stage | Typical setting | Why it matters |
|---|---|---|
| Heat set (nylon-elastane) | ≤180°C | Stabilises width; higher heat damages elastane |
| Dye bath start | 40°C, pH near neutral with acid donor | Slow, even first uptake |
| Acetic acid route | pH 4.5–5.5 for most milling and metal-complex dyes | Simple pH control when no donor is used |
| Heating rate | 0.5–1°C/min through 50–98°C | Prevents streaks and running shade |
| Dyeing temperature | 95–98°C | Full diffusion and migration |
| Hold time | 45–60 min | Exhaustion and levelling |
| Soaping | 2 g/L, 80°C, 10–15 min | Removes surface dye |
| Fixing (syntan) | 2 g/L, pH 5–5.5 | Better wash and perspiration fastness on dark shades |
Typical industry ranges for acid dyes on nylon; exact values depend on the dye selection and machine.
Common nylon dyeing faults and remedies
| Fault | Main cause | Remedy |
|---|---|---|
| Barré (stripes across the fabric) | Yarn lots with different amine end groups or heat history | Use one yarn lot per order; levelling acid dyes or a barré-covering agent; a disperse dye for pale shades |
| Streaks and running shade | Heating too fast between 50 and 98°C; pH dropped too early | Acid donor, 40°C start, 0.5°C/min ramp, hold at 70°C |
| Unlevel or patchy shade | Poor scouring, oil residue, low levelling agent | Re-scour; increase levelling agent; extend time at 98°C so dye migrates |
| Dye spots | Undissolved dye or chemical | Dissolve every addition in the side tank at 90°C for 15 min |
| Poor wet fastness on dark shades | Dye near saturation, loose surface dye | Proper soaping, then a syntan fixing agent; choose milling or metal-complex dyes |
| Elastane damage, poor recovery | Heat setting too hot | Keep heat setting at or below 180°C |
For more fault cases across knit fabrics, see my guide to knit fabric dyeing defects, causes and remedies.
Expert tip from Kamrul Islam
If a nylon lot comes out stripy, check the yarn before blaming the dye. Most barré on nylon comes from mixed yarn lots, and re-dyeing rarely hides it on mid shades.
How to dye nylon at home on the stovetop
Yes, you can dye nylon at home. Tights, swimwear, windbreakers and wig fibres take colour well, but you need heat and acid; cold-water dyes will not work. Nylon blended with polyester or coated for water repellency will dye pale or not at all.
- Weigh and pre-wash. Weigh the dry item, then wash it with plain detergent to remove finishes. Leave it damp.
- Use a dedicated pot. Stainless steel or enamel, never used for food, with room for the item to move freely.
- Add the dye. Dissolve the acid dye or Rit All-Purpose powder in hot water and stir it into the pot. Follow the pack for the amount per pound of fabric.
- Heat slowly. Add the wet item and bring the pot up gradually to a near simmer (about 85–95°C), stirring often.
- Add the acid. Once hot, add white vinegar or citric acid as the dye maker directs, in two portions a few minutes apart, so the dye goes on evenly.
- Hold and stir. Keep it hot for about 30 minutes, longer for dark shades, until the water looks mostly clear.
- Cool, rinse, wash. Let the pot cool first, then wash in warm water with detergent. A sudden cold rinse can set creases.
Jacquard Acid Dye 4 Colour Set with Citric Acid
True acid dyes for wool, silk and nylon, packed with citric acid, so the right dye and acid come in one box. Brighter and faster on nylon than all-purpose dyes.
Buy on Amazon
Rit All-Purpose Powder Dye, Black
Rit All-Purpose contains dye that works on nylon when used hot with vinegar. Use a generous amount for black, because nylon reaches its depth limit sooner than cotton.
Buy on AmazonJacquard Citric Acid, 1 lb
Does the same job as vinegar without the smell, and is easier to measure. Worth it if you dye nylon or wool more than once.
No products found.For a full black-shade example, read my practical guide on how to dye nylon black with acid dyes. If you dyed the wrong colour, a fabric dye remover can lighten nylon before you re-dye.
Frequently asked questions
What type of dye is needed for nylon?
Acid dyes are the right dye for nylon because they bond ionically with nylon's amine end groups in an acid bath. Disperse dyes work for pale shades only, and household all-purpose dyes work because they contain an acid dye component.
Can you dye nylon fabric?
Yes. Nylon dyes very well with acid dyes or all-purpose dye used hot with vinegar or citric acid. Coated nylon, such as water-repellent jackets, and nylon-polyester blends dye poorly.
What is the nylon dyeing temperature?
Nylon is normally dyed at 95–98°C, heated slowly at about 0.5–1°C per minute from 50°C. At home, a near simmer of about 85–95°C held for 30 minutes or more works.
What pH is used for nylon dyeing?
Most acid dyes for nylon run between pH 4 and 6. Levelling acid dyes work at about pH 3–5, while milling and 1:2 metal-complex dyes work at about pH 5–7.
Can you dye nylon without boiling?
Not well. Nylon needs hot water, ideally close to the boil, for the dye to diffuse into the fibre. Cold or warm water gives a pale, uneven colour that washes out.
Why does my dyed nylon fade or bleed?
Usually loose surface dye was not washed off, or the shade is so dark that the fibre is saturated. Soap the fabric well after dyeing and use a syntan-type fixative on dark shades.
Do polyester and nylon dye with the same dye?
No. Polyester needs disperse dye at about 130°C under pressure, while nylon takes acid dye at about 98°C. A polyester-nylon blend is dyed in two stages, polyester first.
Our verdict
The bottom line
Nylon dyeing works because acid dye bonds to nylon's positive amine sites in an acid bath. Get three things right and most problems disappear: a clean, well-scoured fabric, slow heating to about 98°C with controlled pH, and a proper soap and fix for dark shades. At home, a true acid dye with citric acid on the stovetop gives the best result.
Buy on Amazon
[…] Nylon fabric dyeing process- For practical use […]
[…] Nylon fabric dyeing process- For practical use […]
[…] Nylon fabric dyeing process- For practical use […]
[…] Nylon fabric dyeing process- For practical use […]
[…] Nylon fabric dyeing process- For practical use […]
[…] Nylon fabric dyeing process- For practical use […]
[…] Nylon fabric dyeing process- For practical use […]
[…] Nylon fabric dyeing process- For practical use […]
[…] Nylon fabric dyeing process- For practical use […]
[…] Nylon fabric dyeing process- For practical use […]
[…] Nylon fabric dyeing process- For practical use […]
[…] Nylon fabric dyeing process- For practical use […]