Cool or ash blondes — anyone with lightened, highlighted, or color-treated hair on a cendré, cool-beige, or platinum base who wants to keep yellow and brassy tones from creeping in between salon visits.

It's a consumer at-home product, used in place of a regular shampoo as often as tone needs refreshing; it is not suited to warm or golden blondes, since the cool-toned pigment will push warm hair ashier than intended.

The main reason to reach for it is convenience: rather than a separate purple mask or toning rinse, the cool pigment is built into an everyday shampoo, so tone maintenance happens automatically on wash days without adding a step. That makes it most useful for someone already committed to a cendré or ash-blonde color who wants to stretch time between salon toning appointments.

Use in place of a regular shampoo, adjusting frequency to how quickly warmth returns in your particular tone.

1. Wet hair thoroughly with warm water.
2. Apply a generous amount and massage through scalp and lengths.
3. Leave on for a minute or two to let the pigment deposit.
4. Rinse thoroughly, then follow with a conditioner or toning mask.

Pros:

• Deposits enough violet-blue pigment with each wash to visibly reduce brassiness in cool-toned blonde hair.
• Works as a normal cleansing shampoo, so no separate toning step or extra time is needed.
• Still available here as genuine, unopened stock even though Schwarzkopf has discontinued the line.

Cons:

• Discontinued by the brand, so once current stock sells out it will not be restocked.
• The cool-violet pigment is not a fit for warm or golden blonde hair, which it will push toward ash.
• A complete, verified ingredient list is not available since the product is no longer listed on Schwarzkopf's official site.