Piur London Reactive Pro Smooth Therapy (1000 ml) is a professional hair realignment treatment, the smoothing step of the Reactive Pro protocol, which the bottle describes as engineered for blonde and sensitive hair. Its printed iron range stops at 190 °C, and on lightened hair that ceiling is the reason to choose it. Glyoxylic acid sits second on the ingredient list, Acid Violet 43 adds a violet pigment, and the complete list carries no formaldehyde and no formaldehyde releaser. It processes for 40 minutes at room temperature before the hair is rinsed, dried and ironed.

Why a glyoxylic smoothing treatment with a lower ceiling

On lightened hair, the risk in a smoothing service is the heat. This treatment realigns the fibre on a glyoxylic acid base, but its printed iron range stops lower than Piur London's Rebonding treatment, and the formula carries a violet pigment, Acid Violet 43, that works on the reflect while the hair is aligned. The bottle calls this the LuminAlign System™ and prints Shine Enhancement and Blonde Preservation on the front. The pigment belongs to the smoothing treatment; tone stays a colour decision. Your levers are the even spread, the full dry before the iron, and the heat you choose inside the printed range.

Key ingredients

• Glyoxylic acid: second on the list, straight after water. The realignment active.
• Acid Violet 43: 21st on the list, a violet colourant, the pigment in the formula.
• Cetearyl alcohol and isopropyl palmitate: fourth and fifth, the cream base that carries the active.
• Polysilicone-29 and coconut oil: seventh and eighth, conditioning agents.
• Cetrimonium chloride and behentrimonium methosulfate: ninth and fourteenth, conditioning agents.
• Silanetriol and panthenol: 36th and 37th, with shea butter and argan oil further up the list.

What to expect

Less volume and frizz, a smoother, brighter-looking blonde, and hair that still moves. Regrowth comes through in the client's own texture, and how long the result holds depends on how often the hair is washed and what the client uses at home.

Who it is for

• Blonde, highlighted or otherwise sensitised hair carrying frizz and volume
• Clients who want the smoothing without the brassiness a hotter service can bring up on lightened hair
• Salons that want a glyoxylic-acid service for their blonde clients

Who it is not for

• Dark, resistant, never-lightened hair that needs more heat than this range to smooth: Rebonding Keraplex is built for it
• Hair that fails the elasticity test, stretching when wet without recovering: rebuild it first
• Home use: the bottle is marked professional use only

Professional tip

On blonde, the iron is where the colour is won or lost. Start at the bottom of the printed range, look at the strand after the first passes, and only go up if the hair is still not smooth: the passes are your dial before the temperature is.

How to use

Two ways to run it: the directions printed on the bottle, and the Brazilian salon method, which works with the same figures and adds the craft lightened hair needs.

Method A: manufacturer method

1. Apply Smooth Therapy evenly throughout the hair, keeping a distance of 1 to 2 cm from the scalp.
2. Leave on for 40 minutes at room temperature.
3. Rinse with water until the product is removed.
4. Dry 100% with a hair dryer.
5. Flat iron in fine sections at 160 °C to 190 °C, according to the hair type and resistance, 10 to 15 passes per section.

Method B: the Brazilian method

1. Consultation and strand test. Test the most lightened, most porous section, usually the ends or the brightest highlight, not the easiest one. It tells you where in the printed range this hair sits and shows how the violet pigment behaves on the palest fibre. Salon practice, not a step printed on this bottle.
2. Prep wash, then dry. Reactive Pro Shampoo, then dry the hair completely: the treatment goes onto clean hair carrying no water.
3. Protect. Gloves, dark towels, and cover the client's skin and clothing: Acid Violet 43 is a violet colourant and marks skin, towels and porous surfaces.
4. Section and apply. Fine sections, with a brush, keeping the scalp distance in Method A. Comb through so every strand is coated, then take off the excess.
5. Process. For the time in Method A, at room temperature, with no cap and no heat. Watch the palest sections for any lilac cast.
6. Rinse and check. Rinse thoroughly, then feel a strand: residue left in means uneven smoothing, smoke at the iron and, here, uneven violet.
7. Blow-dry gently. Dry 100%, smooth, on medium heat: lightened hair is the hair to keep the dryer gentle on.
8. Seal by hair condition. Stay inside the range in Method A. As general salon guidance, highlighted or lightly lightened hair in good condition goes toward the top of it; heavily bleached, fine or fragile hair at the bottom, around 160 to 170 °C; hair that was borderline at the strand test stays at the bottom. Never above the top of the printed range. Slow, even passes within the printed pass count.
9. Air. Extraction or an open window at the iron step.
10. Aftercare. Leave the hair loose, and book any tone refresh after the service rather than right before it. At home, the client moves onto Reactive Pro Home Care.

Where it fits in the Piur London range

Smooth Therapy is the service itself, and Reactive Pro Shampoo is the preparation wash that runs before it. After the appointment the client looks after the hair at home with Reactive Pro Conditioner Home Care at every wash and Reactive Pro Mask Home Care as the intensive treatment. For dark, resistant hair, Rebonding Keraplex runs the same two-product logic with a printed range that reaches higher. Stabilizer, from the Sensorial Repair range, is a separate spray, not a step of Reactive Pro. All of it sits in Piur London Professional.