Here I discovered that not everyone knows how gel and cream differ from each other. In short, a gel is almost a solid body, only now for some reason it is liquid or soft, and a cream is an emulsion (a mixture of immiscible). From a cosmetics consumer's point of view, the difference lies in texture. In fact, everything is much more interesting there.
The first practical difference is that a gel is a skeleton of something solid and a payload. The mesh or matrix of the gel can be formed from aluminum oxide, from gelatin (yes, it is hard until it forms a gel), polyvinyl alcohol, and various polymers. This is a high molecular weight fraction, that is, macromolecules, the voids in the geometry of which are filled with a load - a low molecular weight fraction of the gel. It is called the dispersed phase. Often this is water, simple alcohols or organic compounds (hydrocarbons).
The same silica gel that is in packages with electronics and regulates humidity in them is a dry gel. Polysorb (colloidal silicon dioxide), which some of you drank for poisoning, is also a dried gel. Etc.
And the gel can also become a liquid crystal and vice versa. This is an important property of the cell biomembrane bilayer, which is critically important in animal hibernation.
Now let's figure out why and when a gel is used instead of a cream, and what a cream is in general.
What is cream
Cream is a mixture of immiscible liquids. Most often we are talking about oil and water. As you know, if you carefully pour oil, water and kefir into a glass, they will not mix. If you drink it, after a while a kind of cream will form in your stomach, but you will not have time for that.
If you start whipping the butter with water, then two states of the emulsion can form:
- Direct: this is when a very small drop of oil is “wrapped” in a layer of water.
- The opposite: vice versa, when a drop of water is "wrapped" in a layer of oil.
In both cases, there are no strong molecular bonds between the phases, the main retaining force is the surface tension force. That is, it is enough to mechanically process both phases in one container for some time, so that they separate into small drops and “stick” to each other. Naturally, we do this in bioreactors, where you can control all environmental conditions, and guarantee the purity of mixing, and control the machining so that everything goes slowly and accurately. The process of creating a cream is a long meditative stirring at a given speed under specified conditions. If the phases have been prepared correctly, then a cream with the desired texture is obtained.
That is, an ordinary cream in most cases is an oil or ether, to which 90% of water was added “for volume”. Which, as you understand, is very popular with cosmetics manufacturers, because all the active ingredients are in this very oil (or they are), and water helps to properly apply it to the skin and correctly sell a large tube instead of a small one.
In this most popular form, we have direct emulsion, that is, oil in a membrane made of water. The inverse emulsion is made much more complicated, and the cost of the finished product is much higher. The inverse emulsion is very greasy. In practice, this means that inverse emulsion creams are most commonly found among dry or irritated skin products and should not be applied to oily or young skin. These are atrophic creams, age creams, diaper products. The inverse emulsion very well covers the skin with a layer on top and prevents transepidermal water loss, additionally protects. That is, with such cosmetics we create an additional protective layer that lasts for some time. This helps a lot to maintain a visually youthful appearance. The disadvantage of this method is that the skin still needs access to air and cleaning,therefore, this environment is only suitable for those situations where problems with water loss have already begun.
There is a third type of emulsion - pseudo-emulsion. This is when a water-based gel is taken that has minor emulsifying properties. The oil phase is already "wrapped" in it. Under the microscope there will be an aqueous phase of the gel, and inside there is a drop of oil. But a single "drop" of such a gel will be much larger than in the case of direct and reverse emulsions. The pseudo-emulsion has the properties of a cream, it is technologically easy to prepare and very pleasant on the skin: not sticky, there is no excess grease, while leaving access to air on the skin.
What is the Difference Between Cream and Gel
The matrix (frame) of the gel makes it non-flowable, allows it to maintain its shape (most often it is about the shape of the snot), and gives some plasticity and elasticity. If you replace the word "gel" with the word "jelly", then you will not be mistaken, the meanings are the same. But we are professionals, so we cannot say that we have "jelly for intensive regeneration" or "SPF-jelly" in our tube.
The gel is quite easy to make in terms of production cost, but it is easily unstable thermodynamically. And this is critical, because for our Russian conditions, I always lay down a three-year shelf life: two years in logistics and on the shelf in a pharmacy according to the standard, and another year for the shoals of forwarders. The last thing I want to do is return the batch and investigate what went wrong if some idiot again does not transport the batch in the back of a truck within a given temperature range. Therefore, I prepare all the gels for transportation to the Far East, understanding the specifics of domestic logistics.
Gels often have the necessary electrical conductivity (that's why we make tons of ECG gels, and not destructive electrodes), or the required acoustic qualities (most likely, the last time you had an ultrasound, it was our acoustic gel). All thanks to the frame.
Working with gels is the ability to collect the required polymers (and our cozy laboratory was just born from the Research Institute of Polymers in the USSR) and control of the reaction. When you start adding the payload (dispersed phase) to the gel, it is important to check that it does not react with the matrix, packaging and with itself after a year and a half and does not create new unexpected compounds. As a rule, those who have been on the market longer can make more complex gels. You need to be able to. But usually everything inside the gel is packed tightly enough and does not run away anywhere. What can not be said about the cream. If you open a jar of cream bought at the nearest grocery store, and there is water - then you should know that it began to "stir" back, that is, from the state of drops with membranes, it turns into two immiscible liquids.
This is why, when you are doing professional cosmetics or medicinal products in the form of a cream, it is very important to do a huge number of formula stability tests. The more active substances you put in (we are talking about both the concentration and the amount of the substances themselves), the more unstable the formula is on average. Especially in this regard, organic substances that are obtained from organic sources are unpleasant: for example, salts of hyaluronic acid of cadaveric origin (from the combs of roosters from poultry farms) very often come with proteins that will be potential allergens in the first place, and will destroy the gel for us -second. Therefore, we use pure raw materials from European bioreactors, where peaceful bacteria sit in a vat and synthesize everything exactly according to the terms of reference.Approximately the same problems of "garbage" impurities relate to all sorts of extracts of chamomile and other things, loved by adherents of biocosmetics, but since this is still done in a vat with a ton of chemical reagent and in several stages of reactions-evaporation-separation, then the next question is only how much the manufacturer exactly adhered to the technical process.
If you have high-quality raw materials (oh, how much pain there is in Russia!), Then the problems do not end there: the laboratory's development department collects hundreds of formulas, which are then tested in ovens for several months, and only then go into beta. And then they catch up with challenge tests.
And still a lot depends on the accuracy of the emulsion mixing process and its stable observance up to hundredths of a degree.
How to make direct emulsion
In each company, the technical procedure for the emulsion is established separately, and each time it is a set of crutches, magic constants and almost shamanic actions, which are a commercial secret. The approximate technical process is well known. Our possibilities to mix different things correctly are extremely wide for Russia and even the world, because after all, 22 years of science. We know almost everything about magic constants and some are good at predicting.
The experience of the technologist is also important. If you give excessive processing at the homogenization stage, the emulsion may simply fall apart. It must be handled very carefully.
The oil phase for a direct emulsion is selected according to what kind of cream fluidity we want to get in the end and what sensations it should leave on the skin. In our case, for different products, the oil phase is taken from natural oils, synthetic esters, silicones (they are the most pleasant in terms of sensing on the skin). There are emollient oils, fatty, light, there are volatile oils with a dry finish, and there are with medium spreading. The recipe developer can play with these parameters. If I need an oil-free texture (for oily skin) for youth, then I take ethers. As a result, the emulsion looks like an oil and behaves like an oil, but at the same time allows you to give a dry finish without shine.
After the correct combination of the composition for the oil phase, add a certain amount of emulsifier. We only use those that give the emulsion lamellar structure, akin to the structure of skin lipids. They are called innovative, but we developed them ten years ago, and the first generation of Soviet scientists from our research institute was working on something similar, so for us it's a bit of a button accordion. But innovative emulsifiers might sound cool for advertising. And they are, alas, dear. More precisely - EXPENSIVE. Therefore, we can very often achieve indicators that are absolutely impossible in ordinary cosmetics, but the price on the shelf will be twice as high as analogues. Actually, they just started to solve this with marketing, and mainly for export to other countries.
An emulsifier is a solid, waxy substance. It heats up in the oil phase to about 80–85 degrees and melts. In parallel, we prepare the aqueous phase, most often with 3% glycerin (this is the same alcohol that is used in our body to synthesize fat or for reactions with carbohydrates to form the main energy elements of the cell - ATP). Then we take the phase in the apparatus and, with stirring, add the fat phase with the emulsifier. The homogenizer is a rotary mechanism that rotates 3,000 rpm. It breaks up the droplets of the oil phase and makes it so that it is surrounded by an emulsifier. It is the use of a homogenizer that makes the particle size small, and the smaller the particle size, the more stable the emulsion, all other things being equal. And stability affects the presentation: if there is water or fat from a tube instead of cream, and then the cream itself, only it is strange and in pieces - you know,this is a bad homogenizer or you decided to save on the technical process.
By the way, even this mayonnaise happens. There was a wild surprise with mayonnaise: when we bought one for sandwiches on a business trip, he just picked up the pieces. The experienced eye of the technologist determined that it was a direct emulsion. Despite the fact that in mayonnaise there should be about 67% of the fat phase, this in itself is already nonsense. We took samples of this substance, took it to the laboratory, and examined it. It turned out that some manufacturers make direct emulsion with very interesting packaging. It turns out much cheaper than the normal technical process for mayonnaise with the formation of an inverse emulsion. Yes, the texture is uneven, a humped surface and chunks appear.
The stability of the finished emulsion is determined according to GOST 1991. Then it was determined by eye: they twisted it in a centrifuge under certain conditions and looked whether it was stratified or not. That is, they gave expert assessments on scales at the level: "like, norms", "something is wrong" and "not at all right." Since the process is somewhat strange, and it requires an expensive centrifuge, not all cream manufacturers bother with this. Of course, we have it in our laboratory, but we are not limited to such a test.
Features of production
A lot of things created in the laboratory are then difficult to replicate in production. Cream machines are non-standard, and the result of their work often depends on the qualifications of the employees. Since they are all made by people without the experience of our research institute, there is simply nothing of high quality on the market. During operation, we often find serious shortcomings that do not allow us to make commercial serial batches. We must eliminate and rebuild our own equipment at our own expense. The technical park for the production of creams-gels and everything else in general is a very valuable resource. In our production, for example, the work of past generations of technologists is very clearly visible. The results of labor remain with us.
A recent example is a remote homogenizer in the form of a separate unit. That is, the homogenizer was located outside the apparatus (usually it is built into the cone of the reactor), and the line to the engine was made of an unimaginable diameter. Usually the diameter is 50 mm, and it is about 150 mm. The length of the route is such that the homogenization of the hot process proceeded well, but the phase had time to cool down during the transportation to the reactor cone.
In fact, we have a bioreactor and everything is simpler. Crystallization of raw materials began to occur, which I expected to see at another time. This in nuclear physics "expected at another time" is almost as scary as "oops". We have it just a decommissioned batch. As a result, our employees, together with the engineers, made a sawn-off cut from this track and insulated it. When we bought this thing, it turned out that no one thought about such an effect at all. How they planned to work on this at the target temperatures is not clear.
More recently, we bought a device, started adjusting it and found out that it is generally not suitable for high viscosity creams. I had to sell to those who make ordinary cosmetics for "Auchan", there are other media. Then we bought a new apparatus, but it has a higher working load, and the starting current is such that this is unacceptable for our power plant. I had to maneuver the old apparatus less, fit the inclusion of a new one into the production schedule when many other units were turned off, and generally juggle power. It took several months to bring a new input from the city and begin its test operation. But we are growing.
The reactors themselves are usually a container made of a thick layer of stainless steel with a sufficient chromium content, lined with heating elements. Around there is a "shirt", this is a shell-type thermal layer, where you can pour cold water to cool the reactor, or let hot steam there. The device is equipped with a low-speed frame stirrer, which ensures uniform heating (this is the main function). The homogenizer (which interferes quickly and quickly) is usually either a submersible rotor-stator or an external one in the form of a motor, which outside the apparatus is a separate module with a line. Hot emulsion has to be driven through the pipeline, so it is often more convenient when the homogenizer is already inside. The bottom of the apparatus is conical so that the liquid under the influence of gravity can flow freely without additional effort.Discharge through the conical bottom can be carried out by gravity or by pump, usually in an antiseptic bag placed in a barrel. Barrels are intermediate containers, then tubes are already packed on the packaging line. Average loss on the walls, lines, in the pump hose from 3% to 5% of the cream mass. If we are talking about small batches of professional cosmetics, then the devices are used small. And then the geometry: the larger the volume, the better the ratio with the wall area in terms of possible losses. On small devices, losses are up to 10%, and nothing can be done about it.If we are talking about small batches of professional cosmetics, then the devices are used small. And then the geometry: the larger the volume, the better the ratio with the wall area in terms of possible losses. On small devices, losses are up to 10%, and nothing can be done about it.If we are talking about small batches of professional cosmetics, then the devices are used small. And then the geometry: the larger the volume, the better the ratio with the wall area in terms of possible losses. On small devices, losses are up to 10%, and nothing can be done about it.
Also, the devices often have hatches not only for loading, but also for watching. Sometimes it happens, you watch how the gel is formed. If you love looking into the washing machine at home, then you will love it. The first two times are an unforgettable sight.
All raw materials are imported. There is only Russian water, and that is because we ourselves prepare it very much. A number of proteins are also supplied from Russia, because we have a crazy left-handed friend who loves to synthesize unusual things in his production.
This is how we make creams. It was very difficult to "pack", for example, in a moisturizerfor the face immediately UV protection (these are not metal particles, as usual, creating a white screen, but chemical agents that prevent the penetration of A and B-type rays), oils for the base, an innovative emulsifier from olive oil, hyaluronic acid salts from the same vat (they retain water to carry it deeply transdermally), dexpanthenol, an antioxidant (vitamin E) and more, including a minimal amount of preservative. Each component was selected so as to enhance the function and at the same time not enter into mutual reactions with the rest of the composition. In general, this is our little masterpiece of tight packaging of active ingredients, which is rather difficult to sell, since we got a little carried away by the features. The next version was based on one of the "shot" features, but for a different task: massage cream SPA-Orange, it gives the skin a radiance and does not leave an oily shine, is suitable for massage, protects against cold and heat, for dry skin it is important for regular care. Well, oil-free sunscreen , as you already know from the post about ultraviolet light on a person's face. Many developments are used in scrubs and other products.