This formulation is a really fun and interesting one; it’s a solid, self-preserving body wash that I’m calling Birthday Suit Solid Body Wash. You can customize the colour and the scent, and play with different moulds for all kinds of fun! It’s also easy to make—mix, melt, pour, and you’re done. I had a lot of fun developing this formulation and I hope you have fun making it 😄
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The inspiration for this formulation was a discontinued LUSH product; their Naked Shower Gel. The ingredients list showed the base of the bar was a blend of propylene glycol and sodium stearate; this is the same base many commercial stick deodorants use. After that, the bars were mostly comprised of a blend of different surfactants, colourants, and fragrance oil.
As a rather interesting aside—this is a very similar structure to not-actually-soap melt & pour bases, like this or this. If you take a look at the ingredients you’ll recognize propylene glycol, sodium stearate, and a blend of surfactants to create a solid base that looks like soap. So, with that in mind, you can sort of think of this formulation as your own from-scratch DIY not-soap melt & pour 😂
I started my formulating work by looking at a selection of sample deodorant formulations using a sodium stearate/propylene glycol base, like the one linked on this product page. With a general idea of sodium stearate/propylene glycol ratios, I had my base to add surfactant, fragrance, and colour to. Draft number one came together beautifully, but once left on a drying rack for a day or two the bar got all kinds of slimy and drippy—the bars didn’t contain enough sodium stearate to stay fully solid. So, I worked on increasing the sodium stearate content to create something that was sturdy, solid, and lathers up beautifully.
I used Sodium Coco Sulfate (SCS) as the primary surfactant, just like LUSH did, complimenting it with amphoteric Cocamidopropyl Betaine for a milder overall product. This blend creates oodles of rich, luscious bubbles!
As I worked on this formulation I played with tons of different colour and scent combinations and used lots of different moulds. Because we pour this product while it’s still quite a thin liquid, and then it sets up very firm, it’s a great opportunity to break out some of your more detailed moulds. The pretty-photo bars use a blend of red and orange dyes to create a peachy colour to match the Peach Prosecco fragrance oil I used, and then I filled three of the bumblebee cavities in my silicone honeycomb mold (USA / Canada).
Let’s talk pH a bit. This bar is pretty basic, and it has to be. This bar has a pH similar to that of soap; approximately 9.45. And that’s for a good reason—sodium stearate, our hardening agent, is saponified stearic acid. It’s soap, and soap has to be basic. As you lower the pH of this bar, it gets softer. At pH 8.69 I could dent the bar with a thumb and some effort; pH 8.38 and it dented when I removed it from the mould; pH 7.52 and it was a sticky, soft paste that I accidentally smashed/squished into multiple soggy lumps (I wouldn’t call it “breaking” because it was about as soft as a baked potato and I can’t imagine “breaking” a baked potato 😂). If you’d like to learn more and see the different bars and their varying levels of squishiness, I made an entire video about my experiments as an exclusive for my $10 and up patrons.
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This is a really fun formulation to play with and I had a lot of fun creating different versions and experimenting. I don’t use this bar for my face due to the high pH, but I like it as a body wash. Enjoy!
Relevant links & further reading
- Sodium Stearate in the Humblebee & Me Encyclopedia
- Propanediol 1,3 in the Humblebee & Me Encyclopedia
- Preserving Botanical Formulations Naturally – Part 1 from Botanical Formulations
- Preserving Botanical Formulations Naturally – Part 2 from Botanical Formulations
- How can I incorporate X ingredient into a formulation?
- How much essential oil can I add to this recipe?
- Humectants from Colin’s Beauty Pages
- Propylene Glycol and Polypropylene Glycols from Cosmetics Info
Birthday Suit Solid Body Wash
Cool down phase
0.15g | 0.3% fragrance oil or essential oil of choice
Preheat your oven to 225°F (~110°C).
Weigh the first four heated phase ingredients into a small heat-resistant glass measuring cup or beaker. Stir to combine and bloom the dye. Add the last two ingredients (you’ll need to wear a dust mask when the surfactant is dry) and stir until everything is well distributed. Place the measuring cup or beaker on a cookie sheet, and put everything into the oven. Heat through until everything has melted.
Once you have a clear liquid, remove it from the oven. Quickly weigh in the cool down phase (take steps to protect your scale—watch the video!), stir to combine, and pour the mixture into your mould. Leave it to solidify.
When the bar has started to pull away from the edge of the mould, gently pop it out, and you’re done. Leave the bars for a day or two before using—use as you’d use a bar of soap. Enjoy!
Shelf Life & Storage
Thanks to the high pH and high humectant content, this solid bodywash is self-preserving. I left some of these bars in my shower for over 18 months and they never showed any signs of spoilage.
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 50g.
- To learn more about the ingredients used in this formulation, 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.
- 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 and read this FAQ. I think there’s a lot of room to play with different surfactants with this general formulation idea, but if you switch to a liquid one there’s a good chance you’ll have to re-develop the formulation.
- If you’d like to incorporate an essential oil, please read this.
- I don’t recommend mica instead of a water-soluble dye; you need to pour this while it’s still really thin, and mica will likely settle out as it sets.
- You can use propanediol 1,3 or propylene glycol. I have not tested any other alternatives and cannot recommend any.
- I don’t have any suggestions for substituting out the sodium stearate. If you don’t have it, this formulation probably isn’t for you.
- You cannot make this bar acidic. The citric acid in this formulation lowers the pH a wee bit; I found any more acid started to make the bar soft. If acidity is important to you, this is not a thing you should make.
The water-soluble dyes were gifted by YellowBee.