A Complete Guide To Shampoo Bars
THE ULTIMATE GUIDE TO SHAMPOO BARS
1. Introduction
The following questions, and answers, are compiled from our customer queries over the last few years. We've also added a few more that we know prospective shampoo bar users are unsure of.
Over the years solid bars of shampoo have been gaining popularity as an eco-friendly and effective alternative to traditional liquid shampoos.
This infographic shows the UK sales growth of solid shampoo bars versus liquid shampoo from 2024.
*Infographic & Statistic's Source - UK Cosmetics Industry Reports and Environment Studies 2024
The UK market share of solid shampoo in 2024 stood at 22% compared to 78% for liquid.
Projections for 2025 indicate that the solid share will increase to 28% with the liquid share decreasing to 72%.
65% of consumers think brands should be more transparent about the environmental impact of their products citing this as a major consideration for change.
Whilst 42% are willing to try a solid shampoo bar, 78% declared price to be the overriding deciding factor. So, with this in mind, it's worth noting that because solid shampoo bars give you a better, deeper clean you don't need to wash your hair as often, every three to four days, so will last even longer giving you better value for your money.
Additional key factors influencing purchase is that the United Kingdom's 'beauty market' is experiencing a surge in demand for sustainable and cruelty-free beauty products, plus a 25% increase in demand for organic and vegan products.
Whether your intention is to reduce plastic waste, embrace natural hair care, or simply try something new, this guide will walk you through everything you need to know about solid shampoos.
If you have any other questions let us know in the comments below and we will answer them!
Don't miss out on your storewide 10% discount code by using THANK YOU at checkout too!
2. What Is A Shampoo Bar?
Before we move on to the real questions you want an answer to it's probably best to establish just exactly what the shampoo is.
The word ‘shampoo’ is a variant of the Hindi that translates ‘to press or massage’ hair through cleaning.
A proper definition of shampoo is a cleaning agent that ‘does not leave a soap residue’. As you will read later on, soap is not a shampoo!
Shampoo bars are solid cleansing bars developed specifically for hair. Unlike regular soap, which can be too harsh and dry, they are designed with hair-friendly ingredients to cleanse, nourish, and maintain scalp health.
Ideally, proper hair care requires a balanced, neutral to slightly acidic, product obtained through the use of a blend of mild surfactants that are also gentle on your scalp.
The best natural eco-friendly solid bars should be carefully formulated to suit different hair types and concerns and have a good lather with cleaning and conditioning properties that won’t strip your hair of its natural oils so that it gives you and your hair the best experience and end results.
How can I determine if a shampoo bar is suitable for my hair type, many have asked. That's why we've created a guide to match your hair type with the right shampoo right here: The Right Shampoo For Your Hair Type!
3. Are They Good For Hair?
A reads like a loaded question, but yes they are 'good' in so many different ways, as you will discover from reading on. As pertinent a question as asking are liquid shampoos any good?
One of the key pros of using a bar of shampoo is that, in the main (and I'll talk about quality in a second), you will find that all-natural bars are packed with natural hair-boosting ingredients like plant oils so you won't find your hair drying out and this will even make them suitable for daily use, unlike many conventional liquid shampoos that have many synthetic ingredients.
The real answer lies in the quality of the ingredients. If it is a very low-cost item with little or no information about where the product is created then the odds are that it will not be that great a product for your hair.
Conversely, if it is an expensive product then that doesn’t automatically translate to it being a quality product. Always check the ingredients, the provenance, and the manufacturer!
You will also find they are travel-friendly and longer-lasting than a liquid shampoo. Using the right bar for your hair type will soon get your hair back to its original, shiny, voluminous state as they remove residue left from chemicals in traditional hair shampoos.
Are there any cons associated with using them? Not really a disadvantage but, until you get used to using sustainable bars and natural conditioner bars, it will 'feel different' compared to the way you use a liquid shampoo and conditioner. For some people, it takes a little while to get used to rubbing a bar of shampoo on their hair.
Depending on the hardness of the water in your area, you may find some bars do not lather as much, which can take some getting used to as typically people associate lather with cleaning, which is not actually the case - a good non-toxic bar of shampoo can clean your hair regardless of lathering.
Generally speaking, and all things being equal, there are no more cons attached to a shampoo bar than there might be to liquid shampoo - in fact, quite the contrary, after all, liquid ingredients include up to 80% ordinary water. Now that is a con!
4. Is Bar Shampoo Better?
Much the same as the answer to the question above; generally, and in most cases, you get what you pay for. There are excellent shampoos and there are excellent shampoo bars.
So which is better? Genuine solid shampoo bars are made with natural ingredients; they are gentle on your hair and scalp.
The average mass-produced liquid shampoos often contain harsh chemical-derived ingredients that can strip your hair of its natural oils and cause dryness and irritation.
Amongst the key pros of using quality natural bars, aside from being travel-friendly and seemingly longer-lasting than liquids, they are touted as being able to get your hair back to its original, shiny, voluminous state by clearing away residue left from the chemicals found in traditional hair cleansers.
Always check the ingredients, after that it, comes down to personal choice. Try them both out to compare and see for yourself.
5. Are They Good For Curly Hair?
A good quality bar with all-natural ingredients will be fine for all types of hair, curly or otherwise. The manufacturer should show if this is not the case in their advertising and/or ingredients.
Those with long, porous or overly curly hair especially may also experience first-time trepidation as they find the act of rubbing a bar on their head slightly awkward. However, this is a small negative that is soon overcome with time and familiarity, just as with any new product.
6. Are Solid Bars Worth It?
Presumably, the question here is whether they are worth it in terms of cost, or value for money. The answer is an unequivocal yes. Liquid shampoos contain around 80% water, so it's very costly water you’re paying for when you buy a liquid version.
The main reason water is the prime ingredient in liquid shampoos is so that you can pour it out of the plastic bottle. Who wants more plastic in their house in this day and age?
A secondary factor is that the consumer is given the impression they are getting a greater volume, better value and more product for their money. Clever, and somewhat deceptive, marketing!
When you first use a bar of shampoo you could be forgiven for thinking that it is small for the price, but once you realise exactly how many washes you will get from that (relatively) small but highly concentrated bar that impression will soon change.
Also, don't forget that the main, genuine shampoo bars are made with organic ingredients and these are more expensive compared to cheaper ingredients, which are typically harsh chemicals and water, that you find in liquid shampoos.
7. Are They Better For The Environment?
Without doubt, as they contain no water and are not packaged in plastic then they get the thumbs up from environmentalists, and us.
A single plastic bottle can take 450+ years to decompose, and shampoo bars drastically reduce this plastic bottle waste. Bars are eco-friendly and can be a great way to reduce the carbon footprint while improving hair health and hygiene.
With the right best UK organic shampoo bars, like The Solid Bar Company’s, you will find they are zero-waste, free from SLS, parabens, silicon, and palm oil, and are 100% biodegradable with all-natural vegan ingredients – so no artificial colouring or fragrances – meaning no chemicals and therefore safer for you and the environment, scoring high in the sustainability charts!
We also offer unwrapped bars of shampoo as a further step to being more environmentally friendly.
Shampoo bars also save water. Even though you'll still use an amount of water to soap up, scrub, and then rinse the shampoo out of your hair, the bar itself isn't formulated with the same amount of water if any - in the case of our hair products, NONE whatsoever; they are 100% anhydrous - that gives its liquid counterpart its consistency.
8. Are Solid Shampoos Sulphate-Free?
Some are, and many aren’t. Scrutiny of the ingredients is required to ascertain this. A useful guide to what you don’t want to see in your shampoo can be found here in our blog How To Find The Best UK Shampoo Bar.
All of The Solid Bar Company’s products are sulphate-free and vegan.
Sulphate is a 'salt' that is generally sourced from petroleum or plants (coconut or palm oil) and added to cleaning and personal care items to create lather, giving a stronger 'impression' of cleaning power - as you will read further on, this is not always a good thing!
Sulphates derived from petroleum can be associated with pollution at the point of manufacture to possible health risks from long-term use. Those derived from palm oil are controversial due to plantation destruction. All sulphates can be toxic to marine life when washed down the drain.
9. Are Shampoo Bars Good And Safe For Coloured Hair?
The Solid Bar Company’s solid shampoos are safe and good for coloured hair. All of our hair products have been laboratory tested and are fully EU Cosmetic safety (CPSR) approved.
This is not the case for all solid bars – again, check the ingredients and the manufacturers' recommendations. If a shampoo or a solid shampoo is not safe for coloured hair then this should be clearly stated. Most natural solid shampoos are full of natural oils, which help condition your hair and preserve its colour.
As already mentioned, if the product is not correctly pH-balanced and too alkaline then there is a possibility that your hair colouring will be rinsed out early. If you have concerns about your coloured hair the real ingredient to look out for, and beware of, is sulphates which are to be viewed as 'paint strippers' for your colour; so avoid them!
Additionally, it's worth mentioning that not only are The Solid Bar Company shampoo bars all colour safe, they also work well for all types of hair whether it be long hair, short hair, frizzy hair, curly hair, thin hair and thick hair.
10. Can Shampoo Bars Cause Hair Loss?
If it is a REAL solid shampoo bar and not a soap bar masquerading as a bar of shampoo then this should not occur.
However, If it is a REAL shampoo bar and not a soap bar masquerading as a shampoo then this should not occur. However, if you use soap or other alkaline surfactants to shampoo your hair, they can damage it. Our blog 5 Ways Fake 'Shampoo' Bars Damage Hair provides more information on this subject.
Hair loss is common among men and women. Stress, genetics, hormones, medications, nutrition, health conditions, and other factors can cause hair loss. Genetic hair loss can't be reversed.
A breakage is an exterior event that causes hair to fall out. Hair products such as both shampoo bars AND liquid shampoos can cause hair loss, but again, it is a rare occurrence.
Our bars and ingredients have been tested and approved (see the answer to the question above) so they do not cause breakage or hair loss. If you’ve switched to a solid bar, you may notice changes in your hair as your hair adjusts to a solid shampoo product.
However, if the bar you have been using has caused hair damage or loss then I can guarantee that it is of 'questionable' provenance. Check who made it, where it is made and what the ingredients are.
Then, you will find the reason why the problem has occurred. Not because it is a shampoo bar but because of poor quality and possibly harmful ingredients.
Are solid shampoo good for thinning hair? One of their key features is that they don’t strip your hair. The better bars on the market are formulated with quality ingredients and plant-based essential oils that deeply nourish your hair and scalp, boosting its health and promoting hair growth. While shampoo bars can work well for thinning hair, you should always check out the ingredients before you buy.
11. Can Solid Shampoo Be Used As Soap?
The simple answer is yes, you can use them on your body. If it’s safe to use on your hair then it should be safe to use on your body. Note that the reverse is not necessarily true – see below!
All of our shampoo bars are not soap and come with all the benefits of your liquid shampoo, without the plastic.
We have tested dozens of formulas to develop the perfect 100% plant-based shampoo bar, with all the foaminess, nourishment, and care of a liquid shampoo but in a solid format, meaning zero plastic waste. So, again, if you wish you may use them as a body soap.
This then leads many to ask are shampoo bars just soap?
While both are able to remove dirt and grim and wash away excess oil, the surfactants that allows each product to do the same job are very different. A bar shampoo should have a significantly lower and more acidic pH of about 4.5-6.5 compared to your regular bar soap, which sits at a very alkaline pH between 8-10.
So that's an emphatic 'No' answer to that question.
Better still, if it is a soap bar you are after, we also make highly moisturising Castile soap bars which you can purchase here instead.
12. Can They Cause Dandruff?
This is where we need to dip into some chemistry and consider the pH (potential of hydrogen) in a shampoo.
pH is a figure that indicates the acidity or alkalinity of a substance on a logarithmic scale of 0-14 with a pH of 7 being neutral. Lower values are more acidic and higher values are more alkaline. Your hair and sebum have natural pH levels of between 4 and 5.5.
If the shampoo bar is correctly pH-balanced then there should be no problems for you, BUT if it is a soap bar or not properly pH balanced then irritation can come about - lye-based soaps can be very alkaline products with pH values of 9-11.
Additionally, a proper definition of shampoo is a cleaning agent that ‘does not leave a soap residue’. Unfortunately, soap does leave a residue which means that ‘soap’ is not a shampoo.
Once in contact with water soap leaves an alkaline residue that is harmful to the hair in the form of calcium salts which accumulate in the hair strands, leaving them opaque and tangled. This soap ‘scum’ can also cause itching, exacerbate redness, scaly patches, and dandruff (seborrheic dermatitis), and leave the hair dull.
Also, if hair becomes very alkaline and porous, the cuticle cannot retain the colour as the cuticle fails to hold the new pigments and the colour will rinse out prematurely, so not good for coloured hair either.
Once again, the key to avoiding any problems here is to check the ingredients and provenance of the shampoo bar you are buying!
13. Can Shampoo Bars Damage Hair?
The answers to 8 and 10 above cover a lot of this ground. A REAL shampoo bar should not damage your hair. There may be mild changes in your hair as you adjust to the new product but in reality no more than if you were to change your liquid shampoo for another liquid shampoo.
If you feel that your hair is being damaged in any way by a 'shampoo bar' then stop using it immediately, check the ingredients and the manufacturer out again and there is a 99% chance you will find that it is not a proper pH-balanced shampoo bar with all-natural ingredients but probably a soap bar.
14. Do Solid Shampoos Expire?
Liquid shampoo expires and even the best shampoo bars have an expiry date.
So to answer how long shampoo bars last, that depends somewhat on the manufacturing process, the quality, and the type of ingredients. Then if all of those answers are of a high standard then a shampoo bar can last up to 18 months. You can also help achieve this if you store your products in a dry place, away from direct sunlight when they are not in use.
Although, under normal circumstances, the chances are you will use the shampoo bar well before the expiry date comes around.
15. Do I Need To Use A Conditioner After A Solid Shampoo Wash?
Not necessarily. If you are using a good quality shampoo bar with rich moisturising natural ingredients then your hair can be fine without. One of the key reasons people use conditioners after using commercial shampoos is that many of them contain petroleum products that actually dry your hair and scalp.
16. How Do Solid Shampoo Bars Work?
They work in much the same way as normal liquid shampoo. The key differences are that they are in highly concentrated form and, should contain no water.
Start by wetting your hair and the shampoo bar thoroughly. Ensure your hair is thoroughly wet before applying the shampoo bar. Then rub the bar between your hands and on your hair to make it foam.
Then gently massage the shampoo bar on your hair lathering it from the roots to the tips. Keep massaging into your hair and scalp until all hair is covered in a foamy lather. It may take slightly longer to lather in hard water areas.
Also, be aware that shampoo bars are concentrated shampoos with no water, so you will not need as much lather as you do with liquid shampoos. Too much lather in shampoo bars could mean the shampoo has strong cleansing agents that can dry your scalp. Use your fingers to work the lather through your hair and scalp, just like a traditional shampoo.
Then rinse thoroughly. Make sure to rinse your hair completely to remove any residue.
After use, it is best to keep your shampoo bar in a dry place to maximise its life.
Depending on your hair type, you may need a conditioner bar to maintain softness and manageability so, if you wish, follow on with a natural conditioner bar for more intense hair nourishment.
You can see a short video on how to use a shampoo bar here.
17. Is There A Transition Period When Switching To Solid Shampoo Bars?
With The Solid Bar Company products, we say that there is no transition period and no special regime you should follow.
However, everyone is different so when you first start using natural products - and in particular, if your previous liquid shampoo has been heavily laden with artificial ingredients - your hair may readjust as your scalp rebalances scalp oil (sebum) sometimes by overproducing sebum making your hair may slightly extra greasy or heavy. - do not fear this will very soon pass.
Some people don't experience a transition period at all but it can last a few weeks for others. If you live in a hard water area the transition period is usually longer, a water softener helps hugely although we are aware that these are prohibitively expensive to most of us.
18. How Best To Store Your Bar of Shampoo?
To ensure you get the best out of your bar of shampoo and make it last as long as possible here are a few simple guidelines you should follow:
Keep your bar(s) out of any direct flow of water when not in use.
Place on a dish or rack; preferably one with slats or holes to allow the bar to dry.
Allow drying in a well-ventilated space, out of direct sunlight.
If you really want to keep your shampoo bar in the shower then a draining rack is a must. Also be aware that even if your bars are in a draining rack, you still need to position the rack outside of the flow of water. It doesn’t matter how well the rack drains, if your bars are constantly getting wet, they’ll end up soggy and dissolving.
After following all these simple guidelines, once you’ve washed your hair, you'll find your shampoo bars last much longer.
Should I use a conditioner after washing my hair with shampoo?
Yes, it is recommended to use a conditioner after washing your hair with shampoo. Shampoo cleanses the hair and scalp, while conditioner helps moisturise and nourish the hair, making it softer and more manageable. Using both will give you the best results for healthy and beautiful hair.
After shampooing your hair, conditioning your hair is an important step to lock in all the moisture and make it more manageable To get the best results, make sure the conditioner is evenly distributed and your hair is well-coated
Don't forget to check out the full range of the best UK salon-quality bars of shampoo here.
Finally, don't forget to ask us in the comments below if you have any further questions we can answer for you.
Best wishes,
Rebecca at The Solid Bar Company
PS. While you're here why not check out why our Solid Shampoos Are Planet Friendly!
(This blog was updated in February 2025)
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