Piur London S.P.R. Acidic Closure (1000 ml) closes every S.P.R. service. It goes on after the joint rinse of Protein Infusion and Seal & Protect and works at pH 3.5, the figure that explains the step: an acidic finish that Piur London describes as rebalancing the fibre and sealing the cuticle for a light, mirror-shine finish. It stays on for 5 minutes and is rinsed out.

Why the last step is acidic

The earlier steps of the protocol work on the inside of the fibre; this one closes the outside. Piur London states its Fruit Acid Closure complex at pH 3.5 and describes it as rebalancing the fibre and sealing the cuticle, preserving the results of the earlier steps. Its acids are listed by name: vinegar, glycolic, lactic and gluconic acid, alongside tamarind, lemon and apple fruit extracts. Piur London calls them natural fruit acids. It only does its job on hair that has had the full sequence and a clean rinse.

Key ingredients

• Vinegar and glycolic acid: acids that set the closing pH.
• Lactic acid and gluconic acid: two further acids in the closing complex.
• Tamarindus indica fruit extract: tamarind fruit extract.
• Citrus limon (lemon) fruit extract: lemon fruit extract.
• Pyrus malus (apple) fruit extract: apple fruit extract.

What to expect

Shine and a smoother, lighter feel, the mirror-shine finish Piur London describes. The lengths may feel slightly firmer to the touch than after a conditioner.

Who it is for

• Any hair that has completed the shampoo, infusion and sealing steps
• Salons running the full S.P.R. service

Who it is not for

• A leave-in or general finisher outside the S.P.R. sequence
• Hair still carrying Seal & Protect: rinse it out completely first
• Home use: it is a professional product

Professional tip

This is the step the client sees in the mirror. When the book runs late, cut the blow-dry short, not the closure.

How to use

Two ways to work it: Piur London's directions, and the way we run it in the salon, with the timing left to Method A.

Method A: manufacturer method

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.

Method B: the Brazilian method

1. Check the Seal & Protect rinse is complete, with no slip left on the lengths, then squeeze out the water. Salon practice, not one of Piur London's steps.
2. Apply evenly to mid-lengths and ends, massage in.
3. Leave for the time in Method A, rinse thoroughly, finishing the rinse cool rather than warm.
4. Finish as desired: blow-dry with the nozzle pointing down the shaft.

Where it fits in the Piur London range

Acidic Closure is the last product of the service: the shampoo, then Protein Infusion, then Seal & Protect over it with no rinse in between, one rinse, then Acidic Closure. The four products also come together as the S.P.R. Full Protocol kit. All of it sits in Piur London Professional.