• S.P.R. Acidic Closure (1000ml)

Sensorial Repair · Professional

Piur London

S.P.R. Acidic Closure (1000ml)

Closes every S.P.R. service: after the joint rinse of Steps 1 and 2, to rebalance the fibre and seal the cuticle at pH 3.5.

  • Ships from the UK
  • 4-step protocol
  • Sold individually or as the full kit
£49.50
£49.50
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Description

Dispatch from 1 October 2026. Orders placed now are reserved and dispatched from that date.

What it does

Acidic Closure is Step 3, the Closure Phase, of the S.P.R. protocol, and the final step of the four-step service. Its Fruit Acid Closure complex, at pH 3.5, the only pH declared on a piur London label, uses natural fruit acids to help rebalance the fibre and seal the cuticle, preserving the results of the earlier steps and leaving hair aligned, light and luminous with a mirror-shine finish.

Key actives (as on the label)

  • Vinegar and Glycolic Acid
  • Lactic Acid and Gluconic Acid
  • Tamarindus Indica Fruit Extract
  • Citrus Limon (Lemon) Fruit Extract
  • Pyrus Malus (Apple) Fruit Extract

When to use it

Step 3, the last step of the S.P.R. protocol, straight after the Seal & Protect rinse.

How to use it

  1. Apply evenly to wet mid-lengths and ends.
  2. Massage in and leave on for 5 minutes.
  3. Rinse thoroughly and finish as desired.

What not to do

  • Professional use only.
  • Do not apply over residue from the earlier steps: rinse Seal & Protect out completely first.
  • Not designed as a stand-alone toner or finishing rinse outside the protocol.

The system

Sensorial Repair

Sensorial Repair is Piur London's structural repair line: it exists for fibre worn down by repeated chemical services and heat styling, the kind of hair that reads smooth for a wash or two after a treatment and then starts catching the comb again because nothing was rebuilt inside the cortex.

The line deposits botanical peptides, amino acids and marine minerals into the cortex and holds them there with a lipid seal, then closes the cuticle at an acidic pH so the deposit stays put through washing.

In the chair, read the chemical history first, then sequence the steps in order, infuse, seal, close, without rinsing between the infusion and the seal, because that is exactly where the peptide is lost if a step is skipped or rinsed early.

Her ends stop fighting the brush.

Within Sensorial Repair, three professional tools answer three different moments of the same fibre story. The S.P.R. protocol, Sensorial Porosity Reconstruction, is the full four-step reconstruction service (Shampoo through Acidic Closure). Mask Therapy is the ten-minute option for when there is no time for the full protocol. Stabilizer is the companion product used inside other chemical services, colour, bleach or straightening, rather than a step of its own.

Protocol

Your Sensorial Repair protocol

S.P.R. Shampoo (1000ml)

S.P.R. Shampoo, Botanic Purifying Complex

2 to 3 minutes

Removes impurities and product build-up without stripping the fibre, preparing the hair to receive the botanical peptides of Step 1.

Apply to damp hair and scalp, massage gently, rinse thoroughly before moving to Step 1.

Professional use only. Rinse before proceeding to Step 1.
£38.50
£38.50

Then: Protein Infusion, Marine Bio-Peptide System
S.P.R. Protein Infusion (1000ml)

Protein Infusion, Marine Bio-Peptide System

10 minutes

Deposits botanical peptides and marine minerals along the length to reinforce weakened areas and improve elasticity and strength.

Apply evenly to damp lengths and ends, not the scalp. Heat may be applied during processing if the service calls for it.

Do not rinse. Step 2 is applied directly over Step 1; rinsing at this point loses the peptide infusion.
£115.50
£115.50

Then: Seal & Protect, Abyssinian Peptide Lock
S.P.R. Seal & Protect (1000ml)

Seal & Protect, Abyssinian Peptide Lock

10 minutes

Abyssinian oil forms a lightweight lipid film that locks the Step 1 peptides inside the fibre and aligns the cuticle.

Apply evenly over Step 1, lengths and ends, without rinsing Step 1 first. Heat optional. Rinse Steps 1 and 2 together once processing is done.

Apply over Step 1, never in place of it. Rinse thoroughly before Step 3.
£115.50
£115.50

Then: Acidic Closure, Fruit Acid Closure, pH 3.5
S.P.R. Acidic Closure (1000ml)

Acidic Closure, Fruit Acid Closure, pH 3.5

5 minutes

Natural fruit acids at pH 3.5 rebalance the fibre and seal the cuticle for a lightweight, mirror-shine finish.

Apply evenly to damp lengths and ends, massage through, rinse thoroughly and finish as desired.

pH 3.5 is the only pH declared on any Piur London professional label; it applies to this step only, not to Steps 0 to 2.
£49.50
£49.50

One protocol, sold as a single decision below.

S.P.R. Full Protocol (4-Step Kit)

The full protocol

S.P.R. Full Protocol Kit

One decision, not several.

The S.P.R. Full Protocol groups the four steps of the Sensorial Repair reconstruction service, S.P.R. Shampoo, Protein Infusion, Seal & Protect and Acidic Closure, into a single kit, so a salon can run the complete in-chair protocol from one box rather than ordering four separate 1-litre bottles.

What's inside

  • S.P.R. Shampoo, 1000ml
  • Protein Infusion, 1000ml
  • Seal & Protect, 1000ml
  • Acidic Closure, 1000ml
£319.00
£319.00

Also in Sensorial Repair

Stabilizer (500ml)
£85.80
£85.80

Mask Therapy (1kg)
£77.00
£77.00

Which Sensorial Repair product is right for you?

S.P.R. Shampoo (1000ml)

Opens every S.P.R. service. Reach for it whenever a full reconstruction protocol is booked, to remove build-up without stripping the fibre before the peptides go on.

Hair type Any hair booked for the full four-step S.P.R. protocol, particularly lengths and ends rougher than the mid-shaft from chemical history.

Not for Not sold or positioned as a stand-alone clarifying shampoo; its role is preparing the fibre for Step 1, not a general wash.

S.P.R. Protein Infusion (1000ml)

The reconstruction step. Used directly after S.P.R. Shampoo on hair reading porous or lacking elasticity from chemical or heat history.

Hair type Lengths and ends with reduced elasticity or strength; not applied to the scalp.

Not for Never used on its own. Without Seal & Protect applied over it, the infusion rinses back out.

S.P.R. Seal & Protect (1000ml)

Applied over Step 1, never in its place, to lock the peptides in before the joint rinse of Steps 1 and 2.

Hair type Same hair as Step 1: lengths and ends carrying the Protein Infusion.

Not for Not a substitute for Step 1 and not a stand-alone sealing treatment outside the S.P.R. protocol.

S.P.R. Acidic Closure (1000ml)

Closes every S.P.R. service: after the joint rinse of Steps 1 and 2, to rebalance the fibre and seal the cuticle at pH 3.5.

Hair type Any hair that has completed Steps 0 to 2 of the protocol.

Not for Not positioned as a leave-in or general finisher outside the S.P.R. sequence; the pH 3.5 formula is built to close the protocol.

Mask Therapy (1kg)

The fast alternative when there is no chair time for the full four-step protocol: everyday wash-and-blow-dry visits, post-colour finishing, or closing a Rebonding or Reactive Pro service. Crosses situations rather than sitting inside one protocol.

Hair type Any professional client with about ten minutes at the basin; not restricted to chemically treated hair.

Not for Not a substitute for the full S.P.R. protocol when the fibre's elasticity itself is the reason for the appointment; that calls for the complete four-step sequence, not a ten-minute mask.

Stabilizer (500ml)

Enters whenever the chemical service itself is the appointment: before, during or after bleach, colour or a straightening service. Crosses every chemical service in the salon rather than belonging to one protocol.

Hair type Any hair undergoing alkaline chemistry; lengths and ends only, never the scalp.

Not for Not a bond-builder and does not replace the rules of the chemical process it is supporting. It is not a step of the S.P.R. protocol itself; it is a companion product used inside other services, including S.P.R.

Frequently asked, by professionals

Can the S.P.R. protocol be used on colour-treated or bleached hair?
Yes. Nothing on the S.P.R. labels restricts use on coloured or bleached hair; the line is built for fibre that has lost cohesion from chemical history in general. If a colour or bleach service is still in progress, Stabilizer is the product that goes with that chemical process, not S.P.R.
Can the four S.P.R. steps be mixed, skipped or used out of order?
No. It is a closed four-step system and each label points to the next step. Step 1 (Protein Infusion) must not be rinsed before Step 2 (Seal & Protect) goes on over it, and Step 3 (Acidic Closure) always closes the service. Running the steps out of order, or rinsing early, loses the peptide infusion.
Is heat required during the treatment?
No. Heat is optional, not mandatory, during Step 1 (Protein Infusion) and Step 2 (Seal & Protect), per the label's own wording. Step 0 (Shampoo) and Step 3 (Acidic Closure) are massaged in and rinsed at normal temperature.
How many applications does a 1-litre bottle of each step give?
The labels and the commercial ficha do not state a yield per bottle. This depends on hair length and density, and is a pending figure: do not quote a specific number of services per litre to a client until the operator confirms an average application count.
Can S.P.R. be used on hair that has previously had a keratin treatment, relaxer or other straightening service?
Nothing on the label excludes previously chemically treated hair. As with any professional service, read the fibre's current condition before starting, rather than relying on treatment history alone.
Does the S.P.R. protocol require a strand test?
No label in the S.P.R. protocol calls for a strand test. If a lightening or straightening service is being carried out alongside or before the Sensorial Repair treatment, follow your salon's own consultation and testing procedure for that separate chemical service.
Is the S.P.R. protocol vegan or formaldehyde-free?
Only Mask Therapy in this line carries the V-Label vegan certification. The four S.P.R. protocol products, Shampoo, Protein Infusion, Seal & Protect and Acidic Closure, do not carry a vegan or formaldehyde-free seal, and the S.P.R. Shampoo itself is not a sulphate-free formula; it lists Sodium Laureth Sulfate.
Does Mask Therapy replace the full S.P.R. protocol?
No. Mask Therapy is the ten-minute option for when there is no time for the full four-step service, or as an add-on after a colour or blow-dry. When the fibre's elasticity itself is what the appointment is about, that calls for the complete S.P.R. sequence, not the mask on its own.