– INGREDIENTS FOR CREATING THE NEXT GREATEST LIPSTICK

Figure 1 Lipstick Ingredient Bases

When looking at the ingredient label for any of the lipsticks on the market, one will see that they contain many of the same ingredients. Those at the top of the ingredient list are the higher-concentration ingredients, and many at the bottom are incidentals. Somewhere at the top of this list you will see many of the same waxes being used as well as oils and esters. The hierarchy remains quite similar. This doesn’t make for much of a difference from formula to formula or brand to brand. Some may be slightly softer than others while others may have more color laydown. Some may exhibit more shine while others may seem to be tackier. All in all these are the characteristics that can be found in a conventional lipstick. However, when looking at the ingredients used, they are all relatively the same from formula to formula. Figure 1 shows examples of some common lipstick ingredients. These basic ingredients are all that is needed to create a lipstick. They may exhibit different characteristics; however, they are just all variations on the same theme.

All the textural differences mentioned above come from the variety of vegetable oils, mainly castor oil (Ricinus communis seed oil), esters, and other solvents that are available to the cosmetic formulator. There are many different vegetable oils, all with different feel characteristics. There are many different polar oils that can be used as a starting point in a lipstick aside from castor oil. Depending on the feel characteristics that are sought after, castor oil can be completely eliminated from the formula. Castor oil is used because it is an inexpensive polar solvent, it is convenient, and it works as a good pigment-wetting agent. But nowhere does it state that castor oil must be used to make a lipstick. Although it is the main solvent used to grind the pigments, other oils can be used.

4.1.2.2 What attributes are we looking for in a lipstick?

First, what attributes are we looking for in a lipstick? Second, what new ingredients are out there and which of them will be suitable in a lipstick formula? And third, what ingredients will deliver these desired attributes? The main attributes that a consumer looks for in a lipstick are that it must be applied with comfort and maintain this comfort as long as it is on the lips, it must have and maintain a high degree of shine, and it must wear for a long time—no less than four to six hours. While these attributes may sound quite easy to achieve, in reality they are very contradictory. It is very easy to create a lipstick with high shine and nice comfortable feel, but to make it long wearing at the same time becomes the biggest challenge.

Shine is a function of melt, and melting means the product is wearing off because it is liquefying. Increasing the wear involves the use of polymers and film formers, and these are usually stiff and uncomfortable on the lips. Increasing wear can also involve increasing the powder loading, which may tend to dry out the lipstick, again affecting the comfort level of lipstick wearing. Conventional lipsticks cannot be made to contain all these attributes together in one product, what everyone in the industry calls “The Holy Grail of Lipsticks.” Many formulators have used this phrase and it turns out to be quite true. It is sort of a balancing act, getting the most out of the ingredients to achieve the maximum level of positive attributes. You can never perfectly achieve everything. I say positive, because along with positive you have negative. The negatives are what formulators try to combat in the product, such as tack, drag, and dullness. That’s the tradeoff you get trying to achieve all the positives. So what new technology can be used to achieve all the positive attributes we are looking for in a lipstick? We will work up to that as we move forward in this chapter.

4.1.2.3 TRADITIONAL INGREDIENTS USED IN CREATING A LIPSTICK

The most common ingredients found in lipsticks are esters. There are thousands of esters that can be used in a lipstick formula. These range from light penetrating esters to heavy viscous liquids and pastes. The only limits to the number of esters that can be used are the different acids and alcohols that are used to create them. With so many different variations, the different feel characteristics that can be exhibited in a lipstick formula should be virtually limitless. And more esters are being developed, as the industry always requires them.

But by using the same ingredients over and over again all we are doing is creating an overabundance of “me too” type products on the market, differing only in the combination of ingredients used and not so much in new technology. This new technology can involve new types of ingredients, the science used to create them, as well as methods for manufacturing; but it is science that will play a key role in the next generation of lipsticks. It is this new technology that we will focus on in this chapter in order to create the next greatest lipstick. It is always technology that creates the point of difference in new products. Otherwise we will just wind up with another product in the “me too” category. It is quite easy, but certainly not considered groundbreaking.

Technology—what is it and how does it relate to lipsticks? After all, the cost of ingredients to make a simple lipstick is just a 5–10¢ combination of waxes, oils, and some other simple components. What can technology possibly do here? Since technology can involve a whole lot of different things, the bottom line is to do something entirely different. And the obvious place to start is with the ingredients. You don’t need many ingredients in a formula to make it feel elegant. It is just the right choice of ingredients that will do the trick.

Of the different types of esters that can be used there is one group called Sugar Esters of Fatty Acids. These are a little different than conventional esters in that they are based mainly on the disaccharide Sucrose (common table sugar which is only derived from plant sources) as a starting point and reacted with a fatty acid to form the ester. Common sucrose fatty acid esters used in cosmetics are sucrose distearate, sucrose palmitate as well as a number of others. They can also be made from fatty acids derived from specific plants: sucrose cocoate, sucrose polycottonseedate, sucrose polypalmitate, sucrose pentaerucate, or sucrose polysoyate, but any fatty acid can be utilized in the esterification process. There are a number of others, but they all cannot be listed here. Their functionality is dependent on the specific fatty-acid chain utilized. They contribute to feel and moisturization owing to their sucrose carbohydrate backbone. They are considered natural ingredients and are approved as direct food additives and even considered natural emulsifiers in some markets. The sugar aids in reducing water loss and helps with adhesion to the lips. Speaking of sugars and carbohydrates, sweeteners (both natural and artificial) are seeing more use in lip products along with different types of fragrances, flavorings, and maskants, and most are GRAS (Generally Recognized as Safe). You see these ingredients mainly in food products, as they are edible.

And speaking of fatty acids, a lipstick formulator can use some natural oils that are high in essential fatty acids. Depending on the oil selected, these provide various amounts of omega-3, -6, and -9 fatty acids. Some plant-derived oils, mainly from the seeds and nuts of the plants, are high in both omega-6 (linoleic acid) and omega-3 (linolenic acid) fatty acids. These are considered unsaturated fatty acids. So a formulator does not have to use fish oils to get the benefit of all three essential fatty acids. Not only do they possess excellent aesthetic properties, they can also be used to make skin care claims with restorative properties as well. For example, kukui nut oil is high in omega-3 and omega-6 fatty acids, so it should see benefits in cosmetics. Oleic Acid, a major component in olive oil, is an omega-9 fatty acid. There are also omega-7 fatty acids. These are also considered unsaturated and the site of unsaturation is seven carbon atoms from the end of the carbon chain. Rich sources of omega-7 fatty acids include macadamia nut oil and sea buckthorn oil.

The next step when using conventional esters of fatty acids is to look for molecules that have longer chains with unique substitutions and branching such as behenates, arachidonates, and erucates. These can add some unique properties to a lipstick formula such as creaminess, cushion, and body. They can be based on saturated or unsaturated fatty acids. This just creates more of a variety of esters based on the fatty-acid starting point. These higher-molecular-weight ingredients perform unlike any of the esters we are currently familiar with and can offer new and unusual feel properties to the lipstick. High-viscosity alky esters such as bis-diglyceryl polyacyladipate-2 offer creaminess and skin protection due to their film forming capabilities. Various butters (hydrogenated vegetable oils) can also serve this purpose.

Figure 2 is a chart that shows what ingredient ratios can be used to create different types of lipsticks. As we stated earlier, a lipstick is a combination of waxes and oils in sufficient ratios to produce a freestanding structurally sound stick. The final selection of waxes will be dependent on their individual melting points, hardness values, and sometimes solubility with the other ingredients in the formula. While the choice of individual waxes may be the same (according to their INCI names), it is the grades of these waxes that may vary. As they are extracted from the plant, waxes have various fractions that have different hardness values and melt points. Different grades of the same wax may even differ in color and odor. This chart shows how the same ingredients can be used to create different types of lip products; most of them are sticks. Essentially there is very little difference in the ingredient selection to create these lipsticks. What if the choice of waxes were to change? What other waxes are available to the formulator that can be used to create a lipstick?

Figure 2

There are some new waxes that have been presented by wax manufacturers to the formulating community. These are neem wax, esparto wax, bayberry wax, sunflower wax, various polyester waxes (based on castor oil), jojoba wax, rice bran wax, and other naturally derived plant waxes that can create a suitable crystalline structure. These in combination with other conventional waxes can add a point of difference to a lipstick. There are silicone waxes that can be used in conjunction with the conventional waxes, which will add significant feel attributes as well as providing hardness to the stick itself. We still need the carnauba and candelilla for strength and shine and we still need to have beeswax for stick shrinkage and mold release. There are yet other waxes based on different chemistries that can be used to create a luxurious lipstick formula.

Hard waxes have a fairly narrow melting point range (around 3–5°C) and usually show a sharp transition when going from the solid phase to liquid phase. Soft waxes on the other hand have a much wider melting point range (around 10–12°C). These undergo a relatively gradual viscosity change around the melting point. This will be evident when running a drop point on the lipstick. The drop point is a relative measure of a product’s melt viscosity but is not exactly the same as its melt point. While the melt point may be sharp and happens quickly, the drop point will take longer for the product to move (drop) or flow. Rheology plays an important role in lipstick formulation. Rheology is very important in a lipstick, as one still wants to inhibit product flow especially at elevated temperatures. Even though a stick is a solid at room temperature and doesn’t really flow, this will help maintain stick integrity when the temperature does start to rise. The stick may get soft as the temperature goes up but we don’t want it to actually melt in its case. We will talk a little more about rheology later on in this chapter.

Silicone waxes act in very much the same way as typical hydrocarbon waxes (various grades of ozokerite or paraffin) in that they go through a phase transition from the solid phase to a fairly viscous liquid phase over a well-defined and predictable temperature range and can be controlled as the silicone molecule is synthesized. This phase transition usually occurs at or slightly above room temperature. What this means is that when a lipstick is applied, the user gets the benefit of a luxurious creamy laydown. Most silicone waxes are compatible with paraffin waxes, making them work well with many of the hydrocarbons we formulate with. Silicone waxes are unique because they have a much higher molecular weight than paraffin waxes and usually have a higher viscosity when they are liquids. Again, depending on the chain length, this can be controlled.

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