Spoiler: the ones I prefer and I keep making are: 1.2; 3.0; and 4.0.
When I started making them, I took inspiration from the recipes I found on a German forum. However, those recipes were made with ONLY sodium cocoyl isethionate as surfactant. No secondary surfactants, no conditioners.
Later, I learned from American websites that – as for liquid shampoos – it is better to combine primary and secondary surfactants also in a solid shampoo. Which makes perfectly sense: a solid shampoo is just a “very concentrated version” of a liquid shampoo. Using just one anionic surfactant still makes it pretty aggressive.
Just to give you some useful sources of information about solid shampoos before you read my recipes:
This time, the powders are mixed immediately with phase B: this makes it easier to incorporate them homogeneously in the shampoo.
I also changed a bit the ratio between the four surfactants, in particular increasing a bit the primary:secondary ratio.
Solid shampoo 1.2 – Nettle, Sidr and Neem again
I made this version in September 2020, when I started to make syndets without splitting the ingredients into two phases. I simply put all the ingredients to be melted together in the same beaker, then added the rest.
This one does not contain any extra-powder (no clay, no herbs). Just surfactants and fat stuff. In this new version I added some neem oil. The result is amazing on my hair, however the addition of extra liquid emollients makes the shampoo bar a bit softer.