Can You Dye Synthetic Hair or Synthetic Wigs? What Works, What Won’t and What to Do Instead

Regular hair dye, box dye, semi-permanent colour and bleach do nothing useful to synthetic hair and can damage it. Synthetic fibre has no cuticle or cortex for pigment to bond with, so the colour washes off, and the ammonia, peroxide and heat in the process can roughen, stiffen or warp the fibre. You can’t make synthetic hair lighter at all. You can sometimes make it darker, using dyes made for polyester fabric or an alcohol-and-ink method, but only on fibres that can take the heat, only to a darker shade, and with results that are uneven and permanent. On a good-quality wig you wear every day, we’d say don’t. On an old wig or a costume piece, read on.

Human hair takes dye because of how it’s built. Each strand has an outer layer of overlapping scales (the cuticle) and a core (the cortex) that holds its natural pigment. Hair dye uses ammonia to lift the cuticle, peroxide to break down the existing pigment, and then deposits new colour molecules inside the cortex where they stay.

Synthetic hair is a plastic filament. It has no cuticle to lift, no cortex to fill, and no pigment to break down; its colour is mixed into the plastic when the fibre is made. So when you put hair dye on it, three things happen. The colour sits on the surface and rinses off. The ammonia and peroxide attack the plastic, which roughens and loses its shine. And if the dye is heat-activated, the heat does what heat does to standard synthetic fibre: it kinks and frizzes. The result is a wig the same colour as before, only worse.

Semi-permanent and “colour depositing” conditioners don’t work either; they’re designed to coat a cuticle that isn’t there. A few people report a faint tint from very dark semi-permanents on pale blonde fibre. It rinses out over two or three washes and it isn’t worth the gamble.

This is the part that decides whether a synthetic wig can be darkened at all, and it’s the part no one explains. Our guide to what synthetic hair is goes into detail; the short version is that wig fibre is one of a few plastics, and they behave differently.

• Standard synthetic fibre (often modacrylic, sold under names like Kanekalon, or a polyester or PVC blend) is heat-set into its style at the factory and cannot take heat again. Above roughly 60°C it softens, kinks and frizzes. That matters because the dyes that work on synthetic fibre need hot water, usually 80°C or more. Standard fibre will not survive a dye bath.
• Heat-friendly (heat-resistant) fibre is made to tolerate styling tools at 130 to 160°C, so it will survive a hot dye bath. It’s the only synthetic fibre on which the fabric-dye method is realistic. Our heat-friendly wigs guide explains how to tell what you have, and our heat resistant wigs collection shows the range.
• The cap, lace and wefts are different materials again, often nylon or polyester, and they take dye differently from the fibre. A dye bath that darkens the hair may also darken a lace front or stain a monofilament top.

If you don’t know which fibre your wig is, the label or the product page will say. If it doesn’t say heat-friendly, heat-resistant or heat-defiant, assume it isn’t.

No. Bleach works by oxidising the pigment inside human hair. Synthetic hair’s colour is part of the plastic; there’s nothing to oxidise. Peroxide will dull the surface and roughen the fibre without changing the shade. You’ll find online recipes using peroxide and bicarbonate of soda that promise to lighten a synthetic wig. In our experience they produce a very slightly faded, noticeably damaged wig, and that’s the best case. If you want a lighter colour, the only route is a lighter wig.

Whatever you decide, dyeing a wig makes it non-returnable. Our returns policy requires wigs to come back in original condition, and retailers generally won’t accept a dyed one.

There is no such thing as synthetic hair dye sold for wigs, whatever the search results suggest. What people use is one of two things.

• Fabric dye for synthetic fibres. Certain dyes designed for synthetic materials, such as Rit DyeMore and iDye Poly, can colour some plastic fibres. However, these dyes generally need very hot water, which can damage a wig’s fibres, lace and cap construction. A dye working on polyester fabric doesn’t guarantee it will work safely on a finished wig. For this reason, we wouldn’t recommend using these products on a synthetic wig you rely on.
• Alcohol-based ink. Alcohol inks or the ink from permanent markers, dissolved in rubbing alcohol and sprayed on, leave a tint on the surface of the fibre. It works at room temperature on any synthetic, which is why it’s popular, but it’s a stain rather than a dye: uneven, prone to transferring onto skin and fabric when damp, and it stiffens the fibre. Useful for a subtle shift on a costume wig, not for an everyday one.

Acrylic paint, food colouring and watercolour are also suggested online. Acrylic paint glues the fibres together; the other two wash out.

You may come across tutorials using fabric dyes or alcohol-based inks to change the colour of synthetic hair. Some people achieve results with inexpensive costume wigs, but the outcome depends on the fibre, original colour and method used.
Alcohol-based colour can leave uneven staining, transfer onto clothing or skin, and affect the texture of the fibres. Hot fabric-dye methods can also permanently damage the hair and cap construction.
At Simply Wigs, we wouldn’t recommend either method for a wig you wear regularly. If you’re hoping for a different colour, our team can help you explore suitable alternatives without risking a wig you love.

Yes. Human hair wigs are real hair, so they take dye the way your own hair does. There are a few differences worth knowing, and they’re the reason we’d always suggest a salon rather than a box dye.

• The hair has already been processed. Most human hair wigs have been cleaned, sometimes bleached and coloured, before you buy them. That makes the hair more fragile than hair on a head, and it means bleach is a bad idea: lifting a processed wig lighter is how wigs end up straw-like.
• Go darker or stay close. A shade or two darker, or a tone change at the same depth, is realistic. Semi-permanent or demi-permanent colour is kinder than permanent.
• Protect the cap. Dye stains lace and monofilament. A stylist who works with wigs will apply colour to the hair and keep it off the cap.
• Strand test every time. Hair from different sources takes colour differently.
• Dyeing voids the return here as well.

If you’d like a colour you can change over time, a human hair wig is the right purchase, and our guide to whether human hair wigs are worth the extra cost weighs it up. Browse our human hair wigs collection, and our wig services include fitting and trimming if you’d like it shaped before it’s coloured.

If you’ve read this far and decided your wig is too good to gamble, here’s how our customers get the colour change they wanted.

• Buy the shade you want. Synthetic wigs come in more colours than any salon could mix, including rooted and shaded blends that no dye bath can produce. Every style in our ladies’ wigs collection can be filtered by colour family, and our guide to matching wig colour to your skin tone helps you choose. If you’re thinking about grey, When Should I Go Grey? is worth a read.
• Ask us for a colour consultation. Send a photo of your current wig and the shade you’re after and we’ll find the closest match across our brands. Book a free appointment or ring us on 01484 844557.
• Wait for the sale. Our monthly offers and Black Friday wig sale can be a great opportunity to add a second colour to your collection. If you qualify for medical VAT relief, you may also be eligible to purchase your wig without VAT.
• Change the colour over your own hair. If you still have hair of your own, a topper in a new shade changes your colour without dye and comes out at night.
• Refresh rather than recolour. Often the wish to dye a wig is really a wish for it to look new again. Removing the shine, restoring a tired synthetic wig, a trim (see cutting a wig) and five ways to refresh it will do more than a dye bath and risk nothing. The right brush and styling products keep it that way.