What is the difference between a shampoo bar and a soap bar?
The only thing they have in common is the shape!
At first glance, a shampoo bar might look a lot like a bar of soap. But it’s not! It’s not anything like soap.
Soap is made from saponified oils. Essentially, it is oil with water and lye added. The lye (sodium hydroxide) turns the oil solid. Then the bar is left to age in order to let the sodium hydroxide convert the oils into soap and glycerin, the components of a cold process soap. Eventually the lye will be gone, and the soap will become very mild. During this time, water also evaporates out leaving a harder bar of soap.
Shampoo bars, on the other hand, do not contain lye. Instead, they contain liquid and powdered detergents that are mixed with fatty alcohols. Fatty alcohols are nothing like isopropyl alcohol. Just like the alcohol you use as a disinfectant has nothing to do with the alcohol that you drink, fatty alcohols are not drying and astringent. They are clear-white beads that melt easily, and re-solidify at room temperature. And they solidify anything you have added to the melt! At StarBars we like to add hydrolyzed proteins, rich oils, and botanical extracts. That is how StarBars become solid shampoo. Of course, there is a balance of liquid ingredients to solid ingredients to be sure the bar stays solid and doesn’t melt all over the shower.
Another difference between soap and shampoo bars is the pH. Do you remember high school chemistry when you learned about pH? An acid is anything below pH 7 (like lemon juice and vinegar) and a base is anything above (like bleach and SOAP!!) Did you know the pH of your hair and scalp is around 5? Shampoo bars are pH balanced (we add citric acid, a natural acid from vitamin c) to get the proper number. Due to the lye in soap, it has to have a higher pH. Using products that are too alkaline will cause damage that raises the cuticle of the hair, increasing porosity and reducing elasticity. This leads to dry hair and frizzy hair.
Finally, the switch from liquid shampoo to hair soap often requires an “adjustment period” of up to a couple of months. This doesn’t happen with shampoo bars. Actual shampoo bars will work from the very first use. StarBars will make your hair look amazing from day one. It’s not soap!
How to tell if it soap or shampoo:
Soap is cheaper and easier to produce. If it is less than $3/oz, it’s soap.
Check the ingredients. If the word “saponified” or “lye” or “sodium hydroxide” is in the list, it’s soap
If it recommends an apple cider vinegar rinse after using, it’s soap
If there is an adjustment period, it’s soap.
