These beautiful Argan Rose Pressed Shampoo Bars were inspired by a popular LUSH product, and I’ve had a ton of fun developing and testing this formulation. It is structured very differently from other shampoo bars I’ve shared, with no melted fatty hardeners like cocoa butter or stearic acid. It also includes water, glycerin, and carrageenan, which all seemed rather novel when I first started working on these, but I’m thrilled with how it’s all turned out. The finished bars lather up incredibly decadently—if there’s such a thing as “too much” lather, this might be it! Rich, silky bubbles for days 😍 I’ve been using this bar as a shampoo and body wash, and I hope you love it as much as I do!
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The bulk of the original bars is Sodium Lauryl Sulfate (SLS), which is pretty apparent when you look at them—you can straight-up see all the wee little sticks of SLS and see that they’re everywhere. After that, there’s some agar agar gel for binding, water, argan oil, glycerine, and a selection of fragrance/essential oils + some red dye. My hypothesis was that, much like a bath bomb, the idea was to get the water-soluble SLS just wet enough that it could slightly dissolve and then re-form into a solid brick as it dried out. Very cool, and very different from other shampoo bars I’ve made in the past.
I made my first version of this bar last year. I started out by trying to incorporate the carrageenan (used instead of agar agar) into the glycerine and water as you would if you were making a slurry to be dispersed in a larger amount of water. That turned out to be a mistake! Without that larger amount of water, I just made an ultra-thick gelatinous blob that couldn’t do much of anything. Whoops! For version two I tried distributing the powdered carrageenan in with the dry surfactants and then slowly adding the rest of the ingredients to that mixture, and that worked much better. While it seems the carrageenan does help hold the bars together initially, it really kicks in when you start to use the bars in the shower. I can feel its characteristic slimy-slip as I use the bar (it’s really nice, I promise!) and the bar is very sturdy throughout use.
The water will dissolve the solid surfactants a wee bit as it moistens the mixture. I included some moisturizing glycerin solely because it’s in the LUSH bar and I wanted to see what I could learn from their inclusion of it. I’ve experimented with glycerine in shampoo bars before; I made one back in 2018 and another in 2019 that contained glycerin and sea salt (a nod to another LUSH bar) and while I loved them once they were ready to use, they took weeks to get there. Even in my very dry climate, they were slimy/damp to the touch for an incredibly long time. With that in mind, I kept the glycerin concentration a lot lower than it was in those bars and didn’t include any salt. I find these bars are perfectly usable within two days, but if you live somewhere very humid you may want to drop the amount of glycerine down and replace it with more water. In the months I’ve been making these bars our dew point has been around freezing (or lower), so it is drrrrrrrry here! Anyhow, my hypothesis is that the glycerin helps keep the bar from cracking through multiple wet-dry-wet-dry cycles, but that needs some more testing!
Regarding drying times; in 24 hours these bars will lose approximately 2–2.5% of their weight and will feel much firmer. By 2 days, we’re at ~3%, and at 3 to 4 days that number has climbed to ~3.25%. After a full week, it’s hovering around 3.5%. I graphed the data and it drops pretty sharply until about the 50-hour mark, where it starts to level off, so I’d recommend leaving these bars to dry for at least two days before use for the best compromise between time for drying and amount of water loss.
Another thing I’m trying with these bars—there’s only one charge of surfactant in ’em (anionic, or negatively charged). While the original bar uses SLS, I’ve used a blend of Sodium Cocoyl Isethionate (SCI) and Sodium Coco Sulfate (SCS), both of which are milder than SLS. Anionic surfactants are very commonly blended with non-ionic and amphoteric surfactants to reduce irritation potential: “To minimize the irritation potential of anionic and cationic surfactants in a cleansing formula, these [anionic] surfactants can be used in small amounts and can be combined with other amphoteric and nonionic surfactants to minimize their irritation potential and negative effects on the stratum corneum… It is assumed that the use of the anionic and amphoteric surfactants results in a milder cleansing formula with a decreased anionic surfactant concentration, decreased skin irritation, and decreased interaction with skin proteins and lipids” (source). I found one pressed shampoo bar currently on offer from LUSH that contains an amphoteric surfactant (Seanik contains Sodium Cocoamphoacetate as one of the very last ingredients), but most of them don’t. I wondered if I’d be able to notice a significant difference between these bars and others I’ve made with an amphoteric surfactant, and I’m not convinced I can. My hair does feel very clean—possibly more clean—with these, but I haven’t noticed any irritation or dryness.
After two or so days of drying these fragrant, bubbly bars are ready to use and utterly lovely. I hope you enjoy them as much as I do!
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Argan Rose Pressed Shampoo Bars
Put on your dust mask and a pair of nitrile gloves. Make sure both fit well; a tight-fitting dust mask does a much better job of keeping powdered surfactants out of your airways, and well-fitting nitrile gloves are much nicer to work in than ones that are sloppily big or too tight.
Weigh the Sodium Cocoyl Isethionate (SCI), Sodium Coco Sulfate (SCS), and carrageenan (the primary phase) into a bowl. Mix with your hands to combine.
Add the secondary phase and mix thoroughly with your hands. Add the tertiary phase, and blend again. You could add the secondary and tertiary phases at the same time if you wanted to—I split them up to encourage/force more mixing for a thoroughly blended product! Whatever you do, be sure the carrageenan is well distributed before you get water anywhere near it to avoid creating a solid blob of glop in the middle of your mixture.
Now it’s time to press the bars! I used the cube mold, pressing 50g of the shampoo bar mixture into each bar. I set the regulated pressure to 55psi. Please watch the video to see this in action. If you don’t have a press you could try hand-pressing the mixture into a firm mold (I don’t recommend silicone as the sides tend to bow out if you really try to compress a mixture in one, and this bar needs some serious squishing). I’ve also heard good things about moon cake presses!
Carefully un-mold the bars (they’re quite delicate directly after pressing, much like bath bombs) and leave them to dry for at least 48 hours before using.
To use, massage the bar into wet hair (or a wet loofah, for body washing) to work up a rich lather. From there on out it’s just like using any other shampoo or body wash. Enjoy!
When made as written, the pH of these shampoo bars comes out to ~5, which is great.
Shelf Life & Storage
Because this cleanser will regularly come into contact with water, I recommend including a broad-spectrum preservative to ward off microbial growth. That said, I have been testing a preservative-free one, and it’s been fine in the shower for a month—it’s promising, but I don’t feel that’s enough data to say it definitely doesn’t need one. Solid shampoo bars have a few “things” going for them that make microbial action challenging, the first being that high concentrations of anionic ingredients inhibit microbial growth (this one in particular is 87% anionic surfactants). Solid shampoo bars also dry between uses, and only a small portion (the outside) of the bar gets wet. I’ll be doing more testing, but LUSH does not preserve their similarly-composed shampoo bars.
As always, be aware that making substitutions will change the final product. While these swaps won’t break the recipe, you will get a different final product than I did.
- As I’ve provided this recipe in percentages as well as grams you can easily calculate it to any size using a simple spreadsheet as I’ve explained in this post. As written in grams this recipe will make 100g (two 50g [1.76oz] bars).
- To learn more about the ingredients used in this recipe, including why they’re included and what you can substitute them with, please visit the Humblebee & Me Encyclopedia. It doesn’t have everything in it yet, but there’s lots of good information there! If I have not given a specific substitution suggestion in this list please look up the ingredient in the encyclopedia before asking.
- I don’t recommend swapping out the Sodium Cocoyl Isethionate (SCI) or Sodium Coco Sulfate (SCS) (including the formats, like choosing a powdered version instead of the little sticks) unless you want to possibly re-develop the formulation.
- You can use a different fragrance or essential oil.
- You could try a different gum instead of the iota carageenan, or a different type of carageenan (kappa or lambda are the ones you’re most likely to find)
- The dye is optional; replace it with more Sodium Coco Sulfate (SCS) if you decide to eliminate it
- If you live somewhere very humid I would reduce or eliminate the glycerine, replacing it with more distilled water
- You could use a different liquid oil your hair loves instead of argan oil
- If you’re like to use a different preservative, please review this page.
- If you’d like to learn more about the surfactants used and compare them to ones you might already have so you can make substitutions, check out this page.
- Make the citric acid solution by combining equal parts (by weight) citric acid and distilled water.