A ‘co wash’ is using only conditioner to wash the hair. Some people do this because they think that shampoo is too harsh or drying or x... However there are a few problems. Conditioner is formulated work after a shampoo and reverse some of the effects. A conditioner will close the cuticle and coat the hair to make if feel smooth and look shiny. It doesn’t clean! Essentially it is very similar to fabric softener and you wouldn’t just use that on dirty laundry! Every time someone tells me they only co wash, I imagine the Febreze advert 😂😂😂 Co washes can be good to refresh your hair in between a full wash and I have seen a few SPECIAL FORMULA co washes that include a cleansing agent. Yes I know shampoo isn’t the only product that can cleanse but your regular degular conditioner is not cutting it