Caroline Hirons has unveiled The Strong Acid, the latest addition to her Skin Rocks acid toner range, describing the formula as 'barely legal' after instructing developers to make it 'as strong as you can... but keep it legal.' The product, priced at £75, contains 15% AHA, BHA and PHA across seven different acids, making it the brand's most powerful exfoliant to date. Hirons warned it is not for beginners, stating: 'If you're new to acid toners, don't go near it.'
The Strong Acid completes the brand's acid trio, joining Control Acid (£49) and Gentle Acid (£53). Control Acid, formulated with salicylic acid (BHA), targets oily, congested or breakout-prone skin. Gentle Acid, described by Hirons as 'our firstborn,' contains 9% AHAs and 1% PHA and is suited to all skin types, including those new to acids and younger users in their twenties and early thirties.
According to Hirons, The Strong Acid is intended for experienced users seeking serious results, addressing skin texture, dullness, hyperpigmentation, lines, wrinkles, blackheads, congestion and visible pores. She emphasised that the exact breakdown of the acid blend is a closely guarded secret to prevent copycats. The product comes in a glass bottle, a deliberate choice Hirons defended, saying: 'People are like, why isn't it in plastic? I'm like, no. It's in glass.'
Hirons advised that due to its strength, The Strong Acid should be applied with cotton pads rather than hands, and used no more than three times a week, building up to every other night. She also cautioned against combining it with her Retinoid 3 product in the same routine, recommending users alternate between the two. For those with sensitised or inexperienced skin, she suggested starting with Gentle Acid instead, which she noted is 'already much stronger than most on the market.'
