This blog post is in response to several blog emails on the same topic.
Any "new" oil you try on your hair is going to be affected by what is already on your hair in terms of residues and hair care products in the process of creating those residues. All conditioners cause build-up. Many shampoos these days do too, as do styling aids.
Cosmetic mineral oil can work very well used over conditioner and conditioning shampoos or treatments, less so over styling aids for detangling, depending on the amount of product and residue on the hair. Cosmetic mineral oil or for many, baby oil is a surface oil. It can replace conditioner, detanglers and treatments. It can do the same things by filling in gaps in the cuticles and replacing lost lipids and moisturize hair better than vegetable oils or silicones. No oil, natural or otherwise is the same or similar to natural sebum.
Coconut oil can deeply penetrate hair to the cortex level. There are other oils that can too, like babbasu oil and palm kernel oil becaue of their high lauric acid content. However, these oils cannot penetrate hair with residues on it, or when used over relatively small amounts of conditioner used afterward on hair that has been clarified, for example. The oils need to be used on well clarified hair and can make excellent hair care treatments.
For use in oil shampoo, the oils mentioned above need to be used on hair first well clarified and then added to a preferably mild shampoo that does not cause build-up. If the oil shampoo is then followed by small drops of cosmetic mineral oil will the oil shampoo be as effective? Probably not. Yes, the oil shampoo can remove the mineral oil but during washing it is still there, hindering coconut oil penetration. Two shampooings will most likely be needed, one to remove the mineral oil and one to allow the coconut oil for example, to deeply penetrate hair.
Can coconut oil and mineral oil both be used in a hair care routine? Yes.
Most people need to clarify their hair every so often. That is a perfect opportunity to use coconut oil as a deep treatment. During washing it out with a shampoo that does not cause build-up, or if heat has been used during the treatment, it can deeply penetrate hair. Note: Most fractionated coconut oils contain no to almost no lauric acid. That means most cannot be used to penetrate hair.
The reason many people have problems with coconut oil is that while it can make a lovely surface oil, it is heavy, can be sticky and used over any residues or even a limited or very small fresh application of conditioner after clarifying hair, it is not going into the hair deeply. Coconut oil is not going to deeply penetrate hair mixed with butters or other waxy ingredients, natural or otherwise, either.
Many people use coconut oil and like it used over conditioned hair. It is working on the hair surface and that can be fine. However, it is the amount of the other products used and the resulting residues that can change that to "crunchy" or "velcro like" hair. The same principles apply to the use of other natural oils that are able to penetrate hair less deeply than coconut, babassu and palm kernel oils. They become surface oils too.
Cosmetic mineral oil can be a multipurpose product for hair care without the drawbacks of other natural oil use: greasy, heavy, sticky hair. It alone can do many things you want an oil to do and more. It cannot replace all coconut oil or argan oil functions and it cannot deeply penetrate hair.