Shampoo bars are a darling of the zero-waste eco-friendly movement, but a lot of people wonder why you can’t just use a bar of soap to wash your hair if you’re using a bar of shampoo.
I asked a few soap makers because I couldn’t get a good answer, and they had some very strong opinions about whether soap and shampoo bars are the same!
As a general rule, shampoo bars and soap bars are not the same thing because of the ingredients used in them, as well as the different pH levels of shampoo and soap. However, many commercial manufacturers do label soap as a shampoo bar for marketing purposes, even though that’s not technically correct. Shampoo bars should have a pH that’s more acidic than soap, and the more basic pH of soap can be too harsh for human hair.
Table of Contents
- pH of shampoo bars vs. soap bars
- How do shampoo bars work?
- How to keep shampoo bars dry
- How to travel with shampoo bars
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pH of shampoo bars vs. soap bars
Caitlin, owner of Botany Barn, explains the difference this way:
“Many would argue that shampoo should be an acidic pH to match the pH of the hair and scalp, while soap is basic and too harsh for the hair. Shampoo bars are therefore typically made with surfactants and oils and things and kept at a pH of 4.5 – 6. Soap is usually more like 8 and made from the saponification of oils with lye. Lots of people make “shampoo bars” that are just soap, though.”
Birgit of Cassia Organics agrees. “The shampoo bars I make are totally different than soap. You should not use soap for hair – even though there are plenty of blogs out there saying you can. No soap is ever properly pH balanced for hair, no matter what ingredients. You just can’t get it low enough, or it ends up not being soap.”
Jess, owner of Sixth Spice adds “The pH is different and so are the ingredients. A lot of suppliers sell melt and pour shampoo bars that are literally soap bases …. it’s terrible. A neutral pH, which is what soap should be, destroys the hair follicle causing breakage, split ends, frizz, dry hair, fly away etc. Shampoo bars should have a pH of 5 and need to be tested after they are made and cured. It’s actually a bit more difficult to make because you have to do more testing and cannot adjust the pH as you go like with a liquid shampoo.”
Laura Anne, owner of Cabbage Patch Soap, says “Shampoo bars are often made differently, they include surfactants and additives that aren’t typically added to handmade soap. Personally I’ve used my handmade soap as shampoo in the past when I ran out of shampoo and didn’t have any problems. Every soaper is going to have a different recipe.”
So the soap makers agree that shampoo bars and soap bars are not the same things. Like Laura Anne, I’ve heard of people who use regular soap to wash their hair, and while that’s probably okay in a pinch, it sounds like you wouldn’t want to do that on a regular basis.
If you do want to try out a shampoo bar, what should you be looking for?
How do shampoo bars work?
Shampoo bars can be used by rubbing them directly onto wet hair to create lather. They can also be rubbed with your hands to create lather that can be applied to the hair, or kept in a cloth or net bag and rubbed onto wet hair. The lather can be massaged into the hair to clean it in the same way that liquid shampoo does, but without the waste of the plastic shampoo bottles.
Shampoo bars don’t have to be used differently than liquid shampoos as far as washing and rinsing the hair goes. I’ve seen people say that they had a hard time rinsing shampoo bar lather out of their hair, but I have a suspicion that’s because they were using a soap bar that’s labeled as shampoo.
I’ve never had any problem with rinsing the shampoo bar lather out, and my daughter hasn’t either. The water in her area is harder than the water where I live, so I don’t know that a real bar shampoo is the problem with rinsing, my guess is that it’s the ingredients.
One ingredient that I find questionable in commercial shampoo bars is Sodium Laurel Sulfate, or SLS. Apparently it’s a fairly common ingredient that creates foaming and lather, and it’s a little controversial for a few reasons.
Birgit says “Sulfates are not the greatest….SLS and SLES (Sodium Laurel Ether Sulfate) are esters of sulfuric acid. I prefer to use SCI (sodium cocoyl isethionate,) which is a bit milder. There is also SAS (sodium alkyl sulfate) and ALS (ammonium laureth sulfate) and these are all often mixed up by consumers!”
The expression “squeaky clean” isn’t necessarily good when it comes to your hair, because that means that the oil has been stripped out of it. Natural shampoo bars usually contain oils that are healthy for your hair and won’t leave it dried out.
So ingredients are one thing that makes shampoo bars different than commercial liquid shampoos. Another thing that’s different is that a bottle of shampoo can sit in a wet shower and not be damaged, but you need to keep shampoo bars dry or they’ll turn into mush.
How to keep shampoo bars dry
To keep shampoo bars dry between uses, they should be kept in a container that either has good drainage or that allows the water to evaporate between usess. Closed containers will trap moisture inside and can soften or even melt the shampoo bar. Using a dish that keeps the shampoo bar out of the shower spray can prevent the outside part of the bar from softening and will extend the life of the bar.
I bought my daughter a shampoo bar that she kept in a container that had a lid, and she said that it totally melted!
She didn’t know that you have to let them dry out between uses, and there was probably water inside the container that dissolved the bar.
(She did say that she still used it, but that it was just mushy.)
I keep my shampoo bar in a little metal can, and the lid is the holder for the accompanying conditioner bar. The dishes sit out of the water spray from the shower, and they have a chance to dry out between uses.
Another way to hold the bars would be to keep them in a little cloth or mesh bag that you can hang up to dry. You could also use these when you’re traveling, which is one benefit of using a shampoo bar instead of liquid shampoo.
How to travel with shampoo bars
One of the benefits of shampoo bars is that you can carry them with you when you travel due to the fact that they’re light and are much smaller than a plastic bottle. Traveling with shampoo bars is not a problem even if you want to keep one in your carry-on bag when you’re flying. Because the bars are solid, they don’t fall into a category of things that are restricted by the TSA, and they won’t require special containers or travel sizes to pass through airport security.
Tucking a shampoo bar into an overnight bag is a lot easier than carrying a full bottle of shampoo with you, even if you were allowed to. It’s also easier to carry them with you’re hiking, camping, or traveling anywhere that you’ll have limited space.
On the Cassia Organics website, the shampoo and conditioner bars are described as being “Travel-friendly and TSA-approved.”
You can easily store a shampoo bar in a plastic bag or in a container with a lid while traveling. Make sure to dry the bar off a little before putting it into a closed container, though, because storing it while it’s really wet can soften it.
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