I make shampoo and conditioner but not with soap nor castile/Bastille soap but with surfactants. Personally, I don't find it hard - kinda like Soapmaking- it's a formula and you need to follow it closely. Because hair produces are water based they need a preservative. I do this because hair is different from skin. The pH levels for acceptable shampoos are very different from soap (I explain further if you keep reading). I don't use anything lye based for shampoo etc and find the formulas easy to follow.
I actually started with chemical formulation books - ancient, outdated, not natural - but they were widely available for cosmetic industry and if you've made hot process soap, I think you'd have no issue. For me, reading and understanding chemical formulas was the lead into soap. I started with chemical formulation and moved into soap making (I assume the opposite of most).
But shampoo is just about understanding what's needed.
You basically need:
Primary Surfactant: main foaming/cleansing agent (30 years ago the most popular would have been SLS - NOT as popular now but still widely used)
Secondary Surfactant: foam building/reduces the drying affect of primary
Viscosity Builders: thickening agents etc. interesting when you think about why. The why, is simply perception (a bit like liquid soap) - our brains equate thickness to how concentrated something is and if you've ever made liquid soap you know this isn't necessarily true.
Stabiliser/Foam Boosters: it's crucial to stabilise the foam boosters added because we aren't making bubble bath so you want some foam bubbles but not lots. Foam boosters aren't necessary but it's a bit like liquid soap again, we like the foaming action because we can see it.
Preservative: 110% necessary and no matter what any one says, vitamin E isn't a preservative it's an antioxidant - it slows oil oxidisation. Anything water based needs a preservative. Same as rosemary extract etc. While some essential oils do have some preservative levels (wrong word, but brain fart) we don't use them in concentrations that would kill microbes etc.
Conditioning agents: yes, shampoo has conditioning agents helps with moisture content, static etc.
Opacifiers/pearlisers: again, it's a brain thing. Consumers equate pearl-esque (my brain hates me again) shampoos to be more luxurious and creamy/rich.
Humectants: Essential for scalp especially but they keep moisture in etc.
pH adjuster: I aim for 3.5 - 4.5. It's interesting as hair natural pH is about 3.7 but scalp pH is 5.5 - scientists consider high pH shampoo as shampoo with pH greater than 5.5 - soap can't get that low and is why it's not great for hair. It's why if you do wash in castile/Bastille soap you need to rinse with ACV. Although it still won't rinse out completely. I've not come across any hair stylist, hair technician or hairdresser that recommends washing with soap.
Fragrance: Essential oils are best especially when used for their properties- rosemary will help, restore, peppermint will invigorate the scalp (helps with hair loss) etc.
Specialty additives: proteins and added nutrients like hydrolised wheat protein, antifungal actives, etc are added for scalp treatment and/or adding nutrients. Depending on hair condition and type. As an example, I make three different shampoos for my family alone - we all have different hair structure, texture and scalp conditions.
Suspending agents: These help water-insoluble additives disperse in shampoo without affecting the stability, foaming, cleansing actions etc.
Chelating Agents: added for hard water, important for people who swim regularly (me) as they have ability to remove chlorine and mineral deposits (eg. limescale) from the scalp and hair. They also prevent colour and fragrance degradation.
Once you understand the different functions of the ingredients and the process it isn't too hard to formulate your own shampoo.
Someone above said that conditioners are just like lotions. This is true. If you've ever made lotion, you will have an idea how to formulate conditioner.
As for formulas I think Elise's blog
WholeElise has a good
basic clarifying shampoo.
I came across Elise's blog when I was trying to find the approximate percentages of Aesop's Handwash as one of my clients loves it so much but would prefer to buy local. I put an Australian twist on the Aesop's with lemon myrtle and bush mint. I also make one with banksia flower and native bee honey - seriously the best smell and sustainable for me as I have several native bee hives and a friend who is a cellular extractor (seriously don't ask me to explain that - it's too complicated).
Also, Tracey from
Oh, The Things We'll Make, makes a great basic
baby shampoo or her
sydnet shampoo bars (made from surfactants) I believe are good for beginners.
My ten year old daughter follows Oh, The Things We'll Make as she has some wonderful crafts and she begged me to use the dishwasher to cook after seeing Tracey's post on dishwasher cooking.
If my daughter can make lotions from that blog, I'm positive others can too.
Both Elise and Tracey have some good basic information and while I'll always advocate books first, I do think these are valuable resources if you haven't made shampoo, conditioner and/or lotions before.
Making shampoos is different from soapmaking but I find it extremely rewarding. My hair was regularly shedding/falling out (scary amount) and although it was/is stress based, the improvement to my scalp condition due to formulating my own shampoo was amazing. I do believe in holistic care but don't believe that vitamins and minerals alone will improve scalp and hair condition.
Edit: corrected spelling