On a Wednesday morning the chair turns and a client sits down for a gloss, six weeks after her last colour. Her balayage is still doing its job. The fade through the lengths reads the way we left it, the parting hasn't drifted, the canopy still catches the light by the front window. What changed in the meantime, in the eight hundred or so hours since she walked out of No. 386, was the work she put in at home. That is the part of the colour grow-out we want to talk about here, alongside the role a keratin blowdry in Glasgow can play when the routine asks for help. The between, the part nobody charges for.

Colour-treated hair behaves differently from virgin hair. The cuticle has been opened, the cortex has been touched, the surface no longer sits as flat as it did before the first foil. Most of what gets sold as haircare treats those facts as marketing rather than craft. This piece is the other way round. We will work outwards from the shaft itself, through the routine that supports it, to the two treatments we apply at the bowl when the hair tells us it needs them.

The shaft, and what colour does to it

A single hair is built from three concentric layers. The cuticle is the outer skin, flat overlapping cells laid down like roof slates. The cortex is the rod underneath, where the keratin sits and where colour lives. The medulla is the open core, sometimes there, sometimes not. The cuticle is what most of your finish-feel comes from, the smoothness, the shine, the way light reads off the lengths. The cortex is what gives hair its strength, and it gets that strength from cysteine bonds, the disulphide bridges that link one keratin chain to another.

When colour goes on, the cuticle is encouraged to lift so pigment can reach the cortex. Permanent colour deposits inside the rod, semi-permanent sits closer to the surface. Either way, the cuticle is now in a different state than it was at birth. It can be coaxed back to a flat lie, but never quite the same. That is why colour-treated hair needs a slightly different routine, and why the routine is not the same on week one as it is on week eight.

What hand-painted colour asks of the cuticle, and why a clean lift matters more than the brand of bleach, is the territory of our separate piece on what balayage in Glasgow actually requires. This piece is what happens to that work after you leave the chair.

The first week after the chair

What we ask of every colour client, before they leave the room, is that they wait at least forty-eight hours before the first wash. The cuticle takes that long to settle back down over the new pigment. Wash sooner and you rinse colour back out of the cortex, in tiny amounts, but enough over time to dull a tone. After that first wash, the work is mostly about restraint.

Wash less than you think you need to. Twice a week is enough for most coloured heads, three times if you train hard or live in heat. The shampoo should be sulphate-free, and free of sodium chloride. Sodium chloride is a thickener used to give cheaper shampoos their body, and it strips the keratin off the shaft, which is the exact opposite of what we want.

None of those points are dramatic. They are just true. The dramatic moves happen at the chair, in the foil and the bowl. The home routine is the steady hand that keeps the work intact in between.

The water in our taps

Glasgow water is soft by national standards. The supply comes mostly from Loch Katrine and runs low in calcium carbonate. That is a small mercy for colour-treated hair, because hard water deposits minerals on the cuticle and dulls the finish over the weeks. Cities further south, fed from chalk and limestone aquifers, are a different story. What we see at the bowl is that our south-side heads carry less mineral buildup than they would in harder-water cities, and the finish holds longer for it.

What we do see at the bowl, though, is buildup from products rather than from the water itself. Dry shampoo through the parting, leave-in conditioner near the roots, styling cream worked through the ends. Over a few washes that residue starts to weigh the hair down and grey the finish. A clarifying wash once a month tends to be enough. Not weekly, that is too much. Once a month, with a proper clarifying shampoo, and a deep conditioner straight after to put back what the clarify takes out.

Heat, and the discipline of restraint

The single fastest way to undo a salon finish at home is to over-heat the lengths. The cortex tolerates heat up to a point, then proteins begin to shift and the cuticle dries open. We see it more at the ends than at the mid-length, because the ends have been through the most washes, the most brush passes, and the most years.

The rule we give clients is to use the iron at no more than one hundred and eighty degrees on coloured hair, and to make one pass per section. Two passes on the same strand is twice the damage, not twice the smoothness. A heat protectant goes on damp, not dry, and gets combed through the lengths, not sprayed at the canopy and left. None of this is exotic. It is just the part of the routine most people skip.

A keratin blowdry, what it does at the bowl

When the routine alone is not enough, or when the hair has been pushed by a colour correction or a fortnight of sea and sun, we turn to a keratin blowdry. The treatment lives in the Treatments tab of the menu and runs to about three hours from arrival to door.

Keratin is one of the body's structural proteins, and it is what hair is mostly built from. A significant share of the strand is cysteine, the amino acid that builds the disulphide bridges that give hair its strength. A keratin blowdry does not break those bridges. What it does is add a layer of keratin to the outside of the shaft, then set it with a hot iron. The published accounts of how the treatment works are consistent on that point. The keratin is added; the iron seals it in.

The visible effect is what brings clients in. The cuticle reads flat, the canopy carries less frizz, the blowdry at home cuts roughly in half. The colour benefit is what brings them back. A sealed cuticle holds tone for longer, and the lift the treatment gives the finish reads particularly well on a balayage, because the cleaner the cuticle, the more the painted lights catch the light.

The chemistry of what happens at the shaft, and why we run a formaldehyde-free formula at the bowl, sits in a separate journal piece on what a keratin blowdry actually does to the hair.

A keratin blowdry at Endz holds for around twelve weeks on a head that washes twice a week with the right products. Push the washes to four times a week, or run salt water through it for a fortnight, and you will see the finish soften sooner. That is not a fault of the treatment, that is the contract. The salon does its work, you do yours.

The treatment sits alongside the rest of the menu on the services and prices page, with the From figure clearly marked, because we never bill from the catalogue, only from what the head actually needs.

Deep conditioning, and the time it takes

The other treatment we apply at the chair is a deep conditioning session at the bowl. The word deep is doing real work in that phrase. A two-minute conditioner in the shower is not a deep conditioner. A deep conditioner is something that sits on the hair, under warmth, for the time the cortex needs to actually take it on.

What we use at the bowl is a protein-and-moisture blend, applied to washed hair, combed through, then left under a warm hood for fifteen to twenty minutes. The warmth lifts the cuticle just enough for the conditioner to reach the cortex. The protein props up the structure where colour has thinned it. The moisture closes the deal. The scalp work that goes with it, a few minutes of slow pressure at the temples and along the hairline, is part of the treatment, not a flourish on top of it.

We tend to recommend a deep conditioning session at the bowl every six to eight weeks for colour-treated heads, often timed to sit alongside the colour consultation we run in the first hour of any new appointment.

The gloss, the toner, the touch-up

Between full colour appointments, there are smaller pieces of work that keep the finish on point. A gloss is a semi-permanent layer that refreshes the tone without lifting anything. A toner corrects warmth that has crept in over the weeks at the canopy. A root touch-up takes the regrowth back to where the colour starts, without going anywhere near the lengths. None of these are full colour, and none of them are billed as full colour.

We try to keep clients off the full colour as long as the work allows, because every full application is a fresh pass over the cortex. The aim is to make the colour live longer between appointments, not to push the client through more of them. The gloss and the toner are the quieter half of the colourist's hand. They earn the trust over years.

What we ask at the consultation

No two heads handle the between-visit period the same way. Density, porosity, lifestyle, water exposure, the products in the bathroom cabinet, the gym, the swimming, the air-conditioning of an office in winter, all of it changes what the right routine is. The consultation is where we take the read.

We look at the cuticle. We feel the weight in the canopy. We ask about the wash cadence and the heat tools and the iron settings. We ask what worked at home and what didn't. By the end, the recommendation is a routine for that head, not a routine off a shelf. It is the same approach we have run on the chair since 1997, refined at this address on Paisley Road West since 2020. The career is older than the door, and the door is the same door for every guest, by appointment, one at a time.

The chair you only leave when the work is right.

Coming back at the right moment

A balayage with a keratin blowdry on top is a piece of colour work that wants twelve weeks before it sees us again. A root touch-up tends to want six. A gloss can be every four if the tone is fading fast on a blonde, longer on a brunette. The number is not the point. The point is to come back when the work is asking for it, not on a schedule from a calendar app. The hair will tell you, if you know what you are looking for, and after a year or two of sitting in the same chair, you will.

If you would like to sit down for the consultation and a read on the hair, the route in is an appointment at No. 386 Paisley Road West, and the rest tends to follow from there.