Thursday, March 8, 2012
Why is everyone so concerned about build up of products on hair?
Some of this is originally from this post on build up from May 22, 2010...
Build-up doesn't have a specific definition, but it's understood to be when our hair has a sticky, gummy, or coated feeling. It is also generally understood to take more than one usage of the ingredient or product to cause build-up, although it can happen (theoretically) with one washing. Anything that is substantive to our hair has the potential to cause build-up - which is why we use them - meaning cationic quaternary compounds (like BTMS or cetrimonium bromide), silicones (like dimethicone and amodimethicone), and cationic polymers (like polyquat 7 or honeyquat)
What causes build-up? Some ingredients we use can cause build-up, and this isn't helped by the water we use to bathe. One of the main culprits in the feeling of build-up is calcium in our water. It can make hair feel dull and rough. This is one of the reasons we see EDTA in commercial shampoo: EDTA is a chelating ingredient that binds to ions in hard water (sodium, calcium, and other metallic elements) and keeps it from depositing on our hair and scalp. We can include EDTA in our shampoo at up to 0.20%.
cetyl alcohol or cetearyl alcohol, in said conditioners as they can increase substantivity and conditioning (note: substantivity and conditioning are good things that can be bad if they lead to build up).
We use cationic quaternary compounds because they offer conditioning properties - reduced friction, static, and impact of combing forces, and improved lubricity. The problem arises when we can't remove the conditioner from our hair when we wash it, generally because we aren't using a well formulated, mild, surfactant based cleanser.
Cationic polymers can build up on our hair over time, but if we use a good surfactant based cleanser, they'll be rinsed out during the next washing. If we're using the cationic polymers in a shampoo, they can form a negatively charged complex with excess surfactant that will resist removal. This is one of the reasons we use the surfactant levels we do in a conditioning shampoo - too much excess surfactant can cause this problem - and the reason we don't use a ton of cationic polymers! This negatively charged complex increases with SLS, for some reason, which is another reason to formulate with more gentle surfactants. (Polyquats 6, 7, 10, 11, and 16 are more likely to resist removal than the other polyquats.)
cetrimonium chloride gets rid of silicones - even a lot of them!)
This is a pretty important aside - you cannot get build up if you aren't using a product. For instance, let's say I use 5 grams of my anti-frizz spray on Monday. I have 100 grams of product, and 20 grams of this is dimethicone. Using 5% of this product means I get 1 gram of dimethicone on my hair. If we tested my hair on Tuesday, you'd see I have slightly less than 1 gram of dimethicone on my hair. If you tested my hair on Wednesday, you'd see that I have less than 1 gram of dimethicone on my hair strands. If I don't wash my hair or put any extra products on it, I will never have more than the original 1 gram of dimethicone in my hair. Walking around, going to work, teaching craft groups, eating food, and so on will not make me have more than 1 gram of dimethicone in my hair. The only way to get more dimethicone in my hair is to add it to my hair via a product. The dimethicone can't replicate on its own and cause more build up on my hair! So you aren't going to get build up over time unless you use a product containing an ingredient that could potentially build up on your hair.
The more damaged your hair, the more potential build-up of the conditioning agents - damaged hair has a higher negative charge, and we know the more negatively charged your hair, the more conditioner is deposited. You want more deposition, but you also need to remove the conditioning agents when cleansing your hair the next time. If you're using intense conditioners or tons of styling products regularly, make sure you also use a clarifying shampoo (no conditioning agents or silicone) and include some cetrimonium chloride in your creations!