Hair Extensions and Texture Treatments: Keratin, Japanese Straightening and Perms with Extensions

Extensions change the conversation about smoothing, straightening and perms. I need to consider your own hair, the added hair and the attachment separately; a treatment that suits one does not automatically suit the other two. I assess your own hair and decide the treatment plan in consultation.

You might want smoother roots with long extensions, a wave that matches both textures, or less time fighting two different finishes every morning. Start with that result. Do not start by booking three appointments and hoping the order works itself out.

Three things to look after

01. Your own hair

I want its history: colour, bleach, previous smoothing, straightening, perms and any trouble at the roots. Bring the names if you have them. Tell me what your hair does after washing and what you want it to do instead. Your added length must not distract us from the hair supporting it. This is my consultation approach, not an online clearance for treatment.

02. The extension hair

Bring the packaging or the exact range, not just “human hair”. I need to know what the supplier permits. Manufacturer instructions differ: one maintenance document rules out chemical work on its extensions, while another manufacturer’s FAQ describes professionally assessed colour and perm options. Those are instructions for particular products, not permission for every pack. source source

03. The attachment

Tape, a keratin bond, a ring, a sewn-in weft and a clip do different jobs. Record the actual system and its care instructions. “Keratin” in the name of a bond does not make it the same thing as a keratin smoothing service. That distinction matters when we decide what can stay in place and what needs a separate plan.

How I work with extensions

I offer work on hair with extensions only to my Loyal Clients.

My preferred treatment for a client with extensions is a keratin treatment, Straightment DEMI. On hair with extensions, a perm is also possible, but it is long, costly and tested first. I would not usually do Permanent straightening on hair with extensions.

Straightment DEMI

1. Take the extensions out before your appointment.
2. They can go back in 3 days after the treatment.

If the extensions are left in

• Nothing is guaranteed.
• £100 is added to your bill for the extra time, once I have assessed the hair. That is not an automatic booking option.
• “Nothing is guaranteed” is about the cosmetic result. It does not remove my duty to do the work with reasonable care and skill, or your legal rights (GOV.UK).

Whatever we choose

• There is no guarantee on previously treated hair.
• You will most likely need a colour update afterwards.

Why it is difficult to work on hair with extensions left in

1. The product has to stay away from the bond. One trade protocol for clients already wearing extensions applies the smoothing solution and the flat iron a quarter to half an inch away from the bond, to avoid slippage (Behind the Chair, updated 2017). The hair next to the bond is then left out, so the finish can look uneven. (The uneven finish is my reasoning, not the source’s.)
2. Bonds and tapes dislike products. Extension makers tell you to keep conditioner and oil off the bond or tape, because it can slip (Cliphair, Great Lengths).
3. Chemicals can break down tape adhesive. Colour is the example one brand gives (Donna Bella, 2018).
4. Heat has limits. Brands cap styling heat on extensions at about 180°C (Remi Cachet).
5. The extension hair may not take the treatment. One extension retailer says a Brazilian blow dry belongs on your own hair, not the extensions (Cliphair, 2025). Some makers rule out chemical treatment altogether.

What you will read elsewhere

• Keratin first, extensions after: Cliphair says to have the treatment before installing.
• Waiting before refitting: one trade article says one week or three washes (Behind the Chair, 2017). My 3 days is my own salon rule, not a figure from a study.
• Washing after keratin on natural hair: UK salons quoted anywhere from 30 minutes to 72 hours (HJI, 2018). Mine is my own rule: same day for Semi and Demi, 48 hours after Permanent, Cold and Hot.

How to book: before, on the day, after

Before

1. Tell me you wear extensions, or plan to. I offer this work only to my Loyal Clients.
2. Send the extension brand, range, attachment and fitting date, and photos of the packaging.
3. Tell me every previous treatment and colour on your own hair.
4. For Straightment DEMI, book your fitter’s removal before my appointment.

On the day

1. The extensions are out before you arrive. If they are left in, nothing is guaranteed and £100 is added to your bill for the extra time.
2. I treat your own hair.
3. After Semi or Demi you can wash the same day. After Permanent, Cold or Hot, do not wash for 48 hours.

After

1. Straightment DEMI: the extensions can go back in 3 days after the treatment.
2. Colour: after Demi, vegetable and semi-permanent colour can be done the same day, and demi-permanent colour and permanent colour wait 3 days; bleach waits a week. After Permanent or a perm, wait at least 2 weeks and have it assessed first. You will most likely need a colour update afterwards.
3. Follow the extension aftercare routine.
4. Send your extension specialist the details below.

What to tell your extension specialist afterwards

Send these four things, in writing, before the extensions go back in:

1. The treatment name. For example Straightment DEMI, Straightment PERMANENT, Wavement COLD or Wavement HOT.
2. The type of chemistry. Keratin or Brazilian-type smoothing, permanent straightening, a cold perm or a hot (digital) perm.
3. The date, and when you first washed.
4. Whether the extensions were in or out during the treatment.

I do not know what is in your extension hair or on your attachment, so ask your specialist what they need from me.

What each extension type can take: what the makers say

This is what extension makers publish. It is not clearance for any treatment, and it is not about my services.

Type	What the makers say	Why it matters
Keratin bond (fusion)	Keep oil and conditioner away from the bond. Keep hot tools off the bond area. One maker rules out chemical treatment of its extensions.	Product and heat reach the bond.
Tape-in	Conditioner near the roots can make tapes slip. Dye chemicals can break down the adhesive, so tape comes off before colouring. Start irons at least an inch below the tape.	Adhesive is sensitive to products and chemicals.
Micro-ring and nano-ring	I found no maker guidance on smoothing or perms.	Ask your fitter.
Sewn-in and glued weft	I found no maker guidance on smoothing or perms.	Ask your fitter.
Clip-in	They come out before any chemical service.	Nothing is attached to your hair.
Heat, all types	One maker recommends no more than 180 degrees. Another gives a ceiling of 350°F, with 250-300°F for regular styling.	Hot tools shorten the life of extensions.

Sources: Great Lengths, Cliphair, Donna Bella, 2018, Remi Cachet, 2022, Perfect Locks, updated 6 Sep 2026.

Before you book

Bring these five things to the conversation:

1. The result you want. Less frizz, less curl, more curl or a better blend are different briefs.
2. Your own hair history. Include previous services even if they were months ago.
3. The extension identity. Fibre, range, colour, attachment and any known processing.
4. The instructions you were given. Photographs of the packaging and written aftercare are useful.
5. Your actual diary. A wedding, swimming holiday, colour appointment or demanding work routine belongs in the plan.

If the history is missing, say so. “I do not know” is useful information. It is better than guessing that the extra hair is virgin or that a previous smoothing treatment has completely disappeared.

Choose the guide that answers your question

• Extension types and attachments: identify what you have before choosing chemistry.
• Keratin treatment with extensions: Semi, Demi and Brazilian-type smoothing.
• Japanese straightening with extensions: Permanent and rebonding decisions.
• Perms with extensions: changing your own pattern versus changing the added hair.
• Extension aftercare: the two-zone wash, styling, sleep and holiday care.
• Extension damage: traction, breakage, chemical and removal problems.
• Colouring extensions: colour, toner and purple shampoo.

Treatment first or extensions first?

For my Straightment DEMI the order is simple: the extensions come out before your appointment and can go back in 3 days after the treatment. For anything else I decide in consultation: I assess your own hair, check the added hair and the attachment, and agree the order. Sometimes the answer is removal by the right professional, reassessment or postponing part of the plan. None of this is a DIY procedure.

Read the full guide to the order of appointments. A calendar gap alone cannot establish compatibility.

First the treatment rule, then the extension rule

My Straightment Semi and Demi allow same-day washing. My Straightment Permanent, Wavement Cold and Wavement Hot require no washing in the first 48 hours. Another salon’s treatment needs its own instructions. Those are my service rules; the extension system can add its own requirements. Being allowed to wash your own treated hair is not automatic permission to wet a newly fitted attachment.

For colour after Semi or Demi, vegetable and semi-permanent colour can be done on the same day, and demi-permanent colour and permanent colour wait 3 days; bleach waits a week. Permanent and perms need at least two weeks before colour, followed by assessment. Do not shorten those rules to make an extension appointment fit.

Stop if it hurts

Pain, persistent pulling, scalp soreness or heavy shedding should interrupt the routine. Stop adding tension and arrange assessment; do not try to hide the problem with a tighter style or another chemical service. Dermatology guidance identifies repeated pulling as a cause of traction-related hair loss. New thinning or scalp changes need medical assessment as appropriate, not an online diagnosis. source

Find the part that changes your routine

The extensions routine tool asks what you are wearing or planning, the fibre, attachment and intended treatment. It keeps unknowns visible. It does not approve chemistry or replace the fitter’s instructions.

You can also read every guide without answering questions. At home, the useful idea is simple: look after the lengths without forgetting what is holding them there. My two-product limit still means two leave-on products in total, including leave-in, gel, oil and heat protection.

Questions

Do you work on hair with extensions in?

Only for my Loyal Clients. My preferred treatment is Straightment DEMI with the extensions out. If they are left in, nothing is guaranteed and £100 is added to your bill.

Which treatment is best if I wear extensions?

Straightment DEMI, a keratin treatment. A perm is also possible. There is no guarantee on previously treated hair.

Will I need to colour afterwards?

You will most likely need a colour update afterwards.

Can I straighten or perm my extensions at home?

I do not recommend it. Cliphair says human hair can hold a perm, that it does not recommend it, and that results are unpredictable (Cliphair).

Does this mean all human hair extensions can be treated?

No. The precise product, its history and its instructions decide what can even be considered. Start with the types guide.

Can the quiz tell me it is safe?

No. It selects the relevant guides and shows restrictions. A result cannot inspect your scalp, your own hair or an attachment.

Do I need a different product for every concern?

That is not my approach. Identify the jobs and respect the attachment instructions; keep within two total leave-ons.

Sources

• Great Lengths aftercare (UK)
• Cliphair tape-in dos and don’ts
• Cliphair: can you perm hair extensions
• Cliphair: Brazilian blow dry, 2025
• Donna Bella: extension colour rules, 2018
• Remi Cachet aftercare, 2022
• Perfect Locks heat styling guide, updated 6 Sep 2026
• Behind the Chair: smoothing treatment 101, updated 2017
• Hairdressers Journal via HJI, 2018
• American Academy of Dermatology: hairstyles and hair loss