Q. Do I really need to shampoo my hair twice every time?
A. ‘Depends how often you wash it – and how well the shampoo lathers,’ says Philip B, who jets between L.A. and New York putting the shine on a roll-call of stars that includes 50something supermodel Dayle Haddon, Brooke Shields and Robert Redford. Often, Philip reveals, manufacturers encourage us to cleanse twice so that we use more shampoo… ‘But if you have oily hair, that inhibits lathering, so you may need two washes,’ is Philip’s insight. ‘The amount of lather is the clue. If you’re getting good foam from the first shampoo, you probably only need one wash. If you’re washing your hair every day, every other day you definitely only need a light wash. The key is to focus on cleansing the roots, where sweat and oil build up, massaging in shampoo with your fingers touching your scalp and working in a circular motion. Add a little water, to emulsify and create lather, then work the shampoo from root to ends before rinsing.’

Q. Can you recommend a pH acid-based shampoo as I’m told this is better than the alkaline-based products as hair is normally acid based. I’ve tried various sites for natural shampoos such as Liz Earle and Aveda but none are clear on this subject.

A. We’re not surprised they’re not clear!  The whole subject of pH-balance is complicated. But the phrase you should be searching for isn’t ‘acid-based’, it’s pH-balanced – and most shampoos (including natural shampoos) are slightly acidic, which works to keep the cuticle smooth and lying flat on the hair shaft. Ingredients like citric acid may be added to acidify the shampoo.  When water’s added to shampoo it can become more alkaline, so sometimes what’s called a ‘buffering agent’ is added.  As we say, most shampoos are pH-balanced, but those that make a point of saying so include Liz Earle Botanical Essence Shampoo, Aveda Damage Remedy Restructuring Shampoo, MOP C-System Clean Shampoo, and their Hydrating Shampoo. Several to start you off with, though as we say, ‘pH-balanced’ isn’t that unusual.

• Liz Earle Botanical Essence Shampoo, £8.50 for 200 ml at www.uk.lizearle.com – buy here

•  Aveda Damage Remedy Restructuring Shampoo, £18.50 for 250 ml at www.johnlewis.com – buy here

• MOP C-System Clean Shampoo, £13.95 for 300 ml at www.johnlewis.com – buy here

• MOP C-System Hydrating Shampoo, £13.95 for 300 ml at www.johnlewis.com – buy here