The acid rinse, IMO, is a partial fix for the problem the soap-as-shampoo causes. The alkalinity of soap causes the cuticle of the hair (the little scales that cover each hair shaft) to open up. This makes the hair rougher and easier to damage.
It's like a frayed rope breaking easier compared to a rope that isn't frayed. This roughness can make the hair look fuller and fluffier when the hair is dried, which some people like. For my and my spouse's hair, however, this roughness reduced the shine of the hair and made our natural waves seem more frizzy.
An acid rinse helps lay the cuticle back down, making the hair shaft smoother. For some people, this acid rinse appears to be enough to cause the cuticle to lay down properly.
For others, an acid rinse helps the cuticle to lay down better but not 100% back to normal. The damage accumulates and becomes permanent, leaving the hair rough and brittle. That's what happened to me, and it's really frustrating because the damage takes some time to become obvious (at least for me). By the time it became obvious, there's no fixing it. Instead I had to cut the damaged hair off and start over.
Scenter Square on Etsy sells ready made syndet shampoo bars and hair conditioner bars. I think she does or did sell kits to make the 'poo bars, including the recipe. If she doesn't have any kits listed, you might ask for availability. Sniff Inside the Box by ScenterSquare
It's like a frayed rope breaking easier compared to a rope that isn't frayed. This roughness can make the hair look fuller and fluffier when the hair is dried, which some people like. For my and my spouse's hair, however, this roughness reduced the shine of the hair and made our natural waves seem more frizzy.
An acid rinse helps lay the cuticle back down, making the hair shaft smoother. For some people, this acid rinse appears to be enough to cause the cuticle to lay down properly.
For others, an acid rinse helps the cuticle to lay down better but not 100% back to normal. The damage accumulates and becomes permanent, leaving the hair rough and brittle. That's what happened to me, and it's really frustrating because the damage takes some time to become obvious (at least for me). By the time it became obvious, there's no fixing it. Instead I had to cut the damaged hair off and start over.
Scenter Square on Etsy sells ready made syndet shampoo bars and hair conditioner bars. I think she does or did sell kits to make the 'poo bars, including the recipe. If she doesn't have any kits listed, you might ask for availability. Sniff Inside the Box by ScenterSquare