Angies formula/HLB/emulsions

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In a message dated 5/18/03 7:45:08 AM Pacific Daylight Time,

flburch@... writes:

>

> I have a question.....what does HLB stand for? Thanks ~Fawn~

Hi Fawn,

I see where the technical and proper definition for HLB has been provided

already. I think to really understand HLB and the logic behind it, one must

have a good understanding of emulsions in general. As I am sure you know,

oil and water don't mix and you will need an emulsifier(s) to make an

emulsion (cream or lotion). One of the oldest methods for making cream used

beeswax, oil and rose water; today we have many different options and types

of emulsions. I would suggest learning about water in oil emulsions (w/o)

and also oil in water emulsions (o/w). The type of emulsion that is created

depends primarily on the type of emulsifier(s) that are used. The

emulsifiers with a lower HLB will generally give you a water in oil emulsion

(something like glyceryl stearate) and the emulsifiers with a high HLB

(something like polysorbate 20) will generally give you a water in oil

emulsion. It is also generally believed that a more stable emulsion is

created when at least two emulsifiers are used---one low and one high. There

are many, many different variations and percentages of emulsifiers that are

used to create emulsions. I think one of the best explanations on emulsions

is from Harry's Cosmeticology--an expensive book to purchase, but it can be

found in the reference section of your library. It would be great if we

could copy the chapter 10 on Cosmetic Emulsification for our files here. The

HLB classic in our files does an excellent job of explaining HLB...and I

believe Maurice's comments and notes will help to explain it also.

If you have ever made a beeswax cream, you have made a water in oil emulsion.

You will notice that it feels greasy. The simple explanation is that the

water molecules are surrounded by the oil molecules and this has been

determined by the beeswax. Sometimes a water in oil emulsion is desirable.

It will repel water and will resist washing. It can also make a nice cold

cream cleanser--like Pond's cold cream that our mothers used. By far the

most popular emulsion is the oil in water type though. Many people are

familiar with the popular self-emulsifying waxes such as 'ewax'. With this,

you will have an oil in water emulsion--where the oil molecule is surrounded

by water. There are more indepth explanations available, but this is

basically what happens. Ewax is a generic term and there will be variation

in the types of ewax--different chemicals are used. But basically all the

emulsifying waxes have an emulsifier or two and a fatty alcohol or two--they

are the key ingredients to form an emulsion. We call these self-emulsifying

because with only water, heat and mixing we can make an emulsion. Almost

everyone will add nice oils or butters and some other nice ingredients to

make a desirable lotion or cream, but an emulsion will form without the extra

ingredients. The self-emulsifier is kind of an instant lotion-maker. I'm

not sure who created the first self-emulsifier, but it was a nifty idea and

makes it easy to make emulsions. The self-emulsifiers always remind me of

the Betty Crocker cake mixes of the 40's or 50's (or whenever they became

popular). In other words, add a couple of ingredients, some heat and mixing

and voila! you have cake....or lotion

With the self-emulsifiers, HLB has already been taken into account. It is

safe to say that most self-emulsifiers will have a fairly high HLB of

somewhere around 15-16. This is determined from the polysorbate that is

likely in the mix. There are some of us who feel that the emulsifying waxes

aren't a particularly efficient way to make emulsions, but I won't go into

that here other than to say the HLB of most ewax is higher than is needed for

most homecrafter's lotions and creams.

Here I should mention that there are two sides to HLB---the required HLB and

the HLB value. The required HLB refers to what's needed by lipophilic/fatty

material to BE emulsified. The HLB value refers to the emulsifier. As

Maurice mentioned, HLB is just a system that was developed to help

formulators determine which emulsifiers will work best to give them the type

of stable emulsion they want in the most efficient manner. So numbers have

been assigned to emulsifiers and also to fatty/lipophilic material that needs

to be emulsified. Think in terms of balance. If your veggie oil has a

required HLB of 7, then you need an emulsifier or combo or emulsifiers that

will be around 7. It's useful to have the two different charts

available--required HLB of oils/fats and the HLB value of emulsifiers. As I

said earlier, it is generally best to use at least two emulsifiers when

making an emulsion---one high and one low. Please see the explanation in the

HLB classic and also Harry's Cosmeticology for more information regarding

options and types. Once the general idea is understood, it's a matter of

figuring the percentages and math for each emulsifier/co-emulsifier. Maurice

has provided some excellent examples. Some people use a spread sheet to more

easily do the calculations. There are many ways to make emulsions, but some

general rules do apply. One of my favorite things to say is that the

possibilities are endless But it's true!

I hope this has not gotten too long and hope that it helps to clarify a

little. I think emulsions are so fascinating and it's well worth learning as

much about them as possible.

Angie

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