I've tried all the different shampoos from Jamaican Mango & Lime, Knotty Boys, Dr. Bronner's, Apple Cider Vinegar to local vendors. The best hands down is Vicki's from the dreadlockshampoo.com site. If that's what your using this go around you should be good to go as she uses sea salt in her liquid formulas. The thing about liquid shampoos for dreads is they do not lather up like shampoo bars or even regular shampoos because most do not and should not contain any lathering agents and chemicals that will accumulate and build up in your dreads. I like the bars as well as you can really scrub the scalp but as my dreads are not fully mature it's best to keep using the Locking Up Liquid shampoo with sea salt.
As for methods I have found that with liquid shampoo it's best if you "prime" your hair and scalp. Really soak the the hair with water, get it as wet as possible, I then work a very small dollop the size of a dime onto my finger tips or palms and scrub my scalp. You won't see much lather but thats okay this is only the priming part, rinse it all off. Now repeat but this time with a larger quarter size dollop, really work it into the scalp and scrub it! As my dreads have matured it gets harder and harder to get at the scalp with my finger tips. I have recently resorted to using my palms and pressing them gently but firmly into the scalp and rubbing it in a slow deliberate circular fashion until the hairs get soft enough that I can get my finger tips to the scalp itself. I then take the excess suds and work them though each individual dread working from the base to the tips. I'll wring them and pall roll them gently working the shampoo deep into the each dread until they are all sudsy. I will let it soak in for a few minutes (about five minutes) soaking in the clean smell and just relaxing my body and mind into the aroma of Nag Champa, Patchouli or any of the other scents I use. I then rinse them all off by staring at the scalp and then wringing the dreads gently from the base to the tips.
Does this take time? Yes, but we should only wash our hair twice a week or every third day so it's not like it's an everyday ritual. Also the scents from Vicki's DreadlocksShampoo smell sooo good that it is a very relaxing ritual that removes a lot of the tension that inevitably builds up in my body from my high pressure job at the hospital so if takes a little longer so be it. These are my dreads why not pamper them. They have become more then extension of my body, they are more like an extension of my inner self, my very spirit and soul.
As far as essential oils, I used to use them as an additive to my homemade sea salt water spray in between washings (use a 3-4% salinity like the ocean, NO MOREfor the typical 8oz / 237ml spritzer bottle this is only two teaspoons of sea salt). I have since starting using Vicki's sea salt spray and honestly the scent from the shampoos will last the three days until the next washing that I no longer see a need to add essential oils to the spray. Experiment with different strengths until you find your ideal. Start light with just a few drops and add from there. Keep track of how many drops of essential oil you added right on the bottle with a Sharpie permanent marker so you can easily remake it or adjust to it.
Lastly I am a big believer in using mother nature's own ocean to help mature dreads. It helps to really frizz up the hair into a bushy knotty mess that dreads up so nicely. I'll spend hours catching waves early in the morning for dawn patrol. The whole day dreads will be poofed out and knotty. I loose a lot of length once they dry out but they look so much more mature and cylindrical.
Hope this helps and keep us posted on your progress this go around,