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Shampoo bars have finally made it out of the depths of the health-food aisles and into the mainstream, with major hair brands including Aveda and Davines recently launching their own cleansing bars.

So, why go solid? Really, the answer is simple: a solid shampoo bar is infinitely more sustainable than a traditional bottle of shampoo, as they typically require little more in the way of packaging than a simple cardboard box.

However, it's hasn't always been easy to make the switch. It's true that many of the early shampoo bars had a pH much higher than that of your scalp, paving the way for irritation and unbalance while making hair drier and prone to frizz. Some were also laden with SLS to ensure a satisfying lather, which can be especially troublesome for colour-treated and naturally curly hair.

Now, however, there's a handful of impressive shampoo bars hitting the shelves that easily stand up to the performance of your favourite formula, all while eliminating plastic waste.

Products featuring our Lab Certified logo have been thoroughly tested in our beauty lab and by our panel of 530 beauty testers.

They blind-trialled 35 brands of shampoo bars over a six-week period to find the products that lived up to their cleansing, smoothing and moisturising claims.

In the lab, our experts used a Dia-Stron machine on hair switches to measure the difference in smoothness before and after using each bar.

Below, you'll find the seven shampoo bars that most impressed our testers, along with three of our editors' picks.

Hair salon brand Percy & Reed’s first shampoo bar is enriched with nourishing vitamin E and avocado oil. Our full panel agreed that their hair felt cleaner after using it and 71% noted that their ends felt softer.

Compact and convenient, it lathered up luxuriously to leave all scalps feeling satisfyingly fresh. It kept its shape without crumbling and our lab team deemed it 'extremely effective' at improving smoothness.

Key Specifications Fragrance free: Yes Sulphate free: Yes Sustainable packaging: Recyclable and plastic-free Size: 50g

Aveda’s much-loved Shampure now comes in solid form, and it’s every bit as impressive as the liquid original. It’s vegan, silicone and sulphate-free, and involves zero plastic packaging. Even the waste produced during manufacturing is sent to the Clean World Foundation, who upcycle it into new soap bars for those who need them most.

Key Specifications Fragrance free: Yes Sulphate free: Yes Sustainable packaging: Recyclable and plastic-free Size: 100g

Transport yourself to the tropics with this mango-infused bar. Its gentle, biodegradable formula helped the majority of our panel avoid any irritation, yet it still created enough lather to rival your liquid shampoo.

One tester said their hair had "never looked better” and 75% of the panel would swap it in for their current shampoo.

Key Specifications Fragrance free: Yes Sulphate free: Yes Sustainable packaging: Recyclable packaging and biodegradable formula Size: 80g

If your scalp is easily upset, you’ve likely shied away from trying a shampoo bar before. This one, however, is specially formulated for sensitive skin, using nourishing neem and karanja oils alongside ultra-gentle coconut-based surfactants. It makes hair feel clean and swishy without leaving the scalp dry. Also worth trying is the brand’s butter-rich, coconut-scented solid conditioner.

Key Specifications Fragrance free: Yes Sulphate free: Yes Sustainable packaging: Compostable and plastic-free Size: 110g

If you go for monthly highlights, switching to a shampoo bar shouldn't compromise your colour.

Happily, this bar did the opposite, with 85% of testers reporting a revitalised shade after washing. The full panel experienced a deep cleanse and 85% enjoyed a boost in softness and hydration.

Key Specifications Fragrance free: Yes Sulphate free: Yes Sustainable packaging: Recyclable and recycled Size: 80g

Davines has transformed four of its targeted shampoos into solid bars this month, and each one comes with promising sustainability credentials. Packaged in 100 per cent recycled paper, each shampoo is sulphate-free and 97.4 per cent biodegradable. All of the carbon generated from production of the bars – including transport – is offset via a reforestation project in Ethiopia.

The Dede shampoo bar is a great all-rounder for everyday cleansing, while the Love bar is a must-try for anyone looking to tame frizz-prone curls.

Key Specifications Fragrance free: Yes Sulphate free: Yes Sustainable packaging: Recyclable Size: 100g

Scoring top marks in our lab test for turning frayed ends silky-smooth, this moisture replenishing bar blends organic coconut oil with ethically traded shea butter. Our testers reported fewer tangles than usual and it left 75% with suitably refreshed scalps.

Key Specifications Fragrance free: Yes Sulphate free: Yes Sustainable packaging: Recyclable, recycled and biodegradable Size: 85g

Claiming to hold the same amount of product as three bottles of liquid shampoo, this bar features moisturising moringa, jojoba and argan oils.

It left 85% of testers happy with their newly hydrated finish and successfully revitalised parched strands in our lab test.

Key Specifications Fragrance free: Yes Sulphate free: Yes Sustainable packaging: Recyclable and plastic free Size: 75g

Catering for all kinks, curls and waves, our panel voted this bar the best for fighting frizz.

Its sulphate-free formula left 75% happy with the look of their curls, while others said their hair felt more manageable to style.

Key Specifications Fragrance free: Yes Sulphate free: Yes Sustainable packaging: Recyclable and plastic free Size: 90g

This honey-scented offering from shampoo bar pioneer Lush explains why the brand has staying power. It thoroughly cleansed 92% of our panel's scalps and left a further 92% with softer, more nourished tresses.

It minimises packaging waste by arriving naked and one tester described its scent as divine.

Key Specifications Fragrance free: Yes Sulphate free: Yes Sustainable packaging: Packaging free Size: 55g