Here’s an ingredient with a mixed pedigree. Lanolin is a pure and rather lovely natural ingredient derived from wool. PEG-75 Lanolin is lanolin that has been ethoxylated. This means that the lanolin is treated with ethylene oxide to make it more water soluble. This enables it to be used in ways that you can’t use lanolin itself.
The 75 bit is important, and represents the degree of ethoxylation. It literally means that there are 75 ethylene oxide units per molecule of lanolin. This is a slightly eccentric naming system from a pure chemistry point of view but it enables a formulator to gauge just how water soluble this material is. 75 is quite a high number as these things go meaning that PEG-75 Lanolin is going to be usable in quite water rich environments such as shampoos. It tends to be used more often in skincare though.
The benefit you get from this surfactant is that it is an effective way of holding oil and water together, but it still has a pleasant skin feel. It is also a way of sneaking lanolin into products past marketing departments. They might well ask the formulator to avoid lanolin because of its poor image with the public. Well it isn’t lanolin. You can meet the letter of what you are being told to do without respecting the spirit. Luckily marketing people don’t have much attention to detail.
What ethoxylated lanolin does very well, and possibly better than anything else, is create emulsions with mineral oil that are easily washed off. This is great for products like makeup remover. Indeed, any product where you want to use mineral oil for its cleansing ability can benefit from it.
This is one of quite a large family of lanolin derivatives that pop up all over the place in products. Lanolin has quite a versatile chemistry that makes it very appealing as the starting point for coming up with new functional ingredients. It hasn’t always been in fashion but it will always impress people who are looking for performance from their personal care products.