Licensed hairstylists, not consumers. This is a salon-exclusive, professional-use product used as the final step of Redken's in-salon Acidic Bonding Concentrate service on clients with damaged, over-processed, or chemically compromised hair. It isn't sold or intended as a take-home retail item, and using it correctly depends on first applying a customized dose of Acidic Protein Amino Concentrate and/or Acidic Moisture Concentrate — a professional judgment call based on the client's hair condition.

A protein or bond-repair treatment does its work while the cuticle is still open, which is also the moment hair is most likely to lose that benefit again on the next rinse. pH Sealer exists to close that window: bringing hair down to a strongly acidic pH right after the treatment step seals the cuticle while the repair is still fresh, which is why Redken positions it as a finishing step rather than a treatment in its own right. For a salon offering the Acidic Bonding Concentrate service, it's the step that determines whether the result a client leaves with actually holds until their next visit.

Professional in-salon use only, as the final step of an Acidic Bonding Concentrate service.

• Apply the appropriate dose of Acidic Protein Amino Concentrate and/or Acidic Moisture Concentrate to the hair and leave for 5 minutes
• Apply 10–15 pumps of Acidic pH Sealer throughout the hair
• Rinse thoroughly

Pros:

• A precisely low pH (3.0–4.0) is specifically what re-closes the cuticle after a protein or moisture treatment, giving an immediate, visible shine result
• Concentrated, pump-dosed format lets a stylist scale the amount used to the client's hair length and level of damage

Cons:

• Only works as intended when used after the correct Acidic Protein Amino Concentrate or Moisture Concentrate step — it isn't a stand-alone treatment
• Salon-exclusive: not available or intended for at-home or DIY use, so it isn't an option for anyone looking for a take-home product