surface active substances (surfactants)

SURFACE-ACTIVE SUBSTANCES (referred to as SAS): Cleansing the skin on the face is the foundation of every skincare routine - only well-cleansed skin can absorb cosmetic active ingredients.

SAS are molecules that have a lipophilic and hydrophilic part.

Products must maintain a healthy oily-acidic mantle (hydro-lipid film) that retains the moisture level in the skin.

They should not damage the skin barrier, harm the hydro-lipid protective film, irritate the skin, and must be suitable for the skin type and condition.

They are classified based on their origin (natural and synthetic) and their role in cosmetic products (anti-foaming agents, emulsifiers of V/O and O/V type, wetting agents, solubilizers, detergents), mechanism of action, and their behavior in the aqueous medium (based on dissociation during dissolution in water, distinguishing non-ionic SAS (do not dissociate in water) and ionic SAS (cationic, anionic, amphoteric, and dissociate in water).

METHODS OF SURFACE CLEANSING OF THE SKIN: solubilizing (based on the use of SAS added to skin cleansing products to improve the contact between lipophilic impurities on the skin and the hydrophilic water medium of the cleaning agent. SAS molecules form micelles upon application, in which lipophilic impurities are trapped, allowing the mixing of lipophilic impurities with the water medium and their subsequent removal from the skin surface), dissolving (based on dissolving lipophilic impurities in a lipophilic oil medium used as a cleaning agent), adsorptive (cleaning masks containing powders such as kaolin, fuller's earth, wheat bran, wheat flour extract, etc .; after application to the skin, water evaporates from the mask, and the polymer forms a film on the skin surface, where dust particles remain trapped, pulling out lipophilic impurities from the skin), abrasive (mechanical peeling, microdermabrasion).

Emulsifiers are linking agents between the aqueous and lipid phases of cosmetic products - they enable the formation of stable emulsions - and in a similar way, SAS for cleansing works, as they increase solubility in water.

The type of emulsion depends on SAS, the ratio of both phases, and the emulsion production process.

An emulsifier with a predominant lipophilic part that dissolves in a lipophilic medium forms V/O emulsions (WATER IN OIL), and vice versa: an emulsifier with a predominant hydrophilic part that dissolves in water forms O/V emulsions (OIL IN WATER).

The selection of natural emulsifiers is extremely limited.

They typically arrange on interfacial surfaces (e.g., between oil and water phases, between the dispersed medium and suspended solid particles) and cause a drop in interfacial tension.

NON-IONIC SAS: compatible with most cosmetic product ingredients, effective cleansers, good solubilizers, and emulsifiers, but weakly foam.

IONIC SAS: ANIONIC (dissociate in water, the surface-active part of the molecule is an anion, ionic parts can be carboxylate, sulfate, sulfonate, phosphate / soaps, alkyl sulfates, alkyl ether sulfates), CATIONIC (dissociate in water, the surface-active part of the molecule is a cation; they do not clean well and do not foam richly, especially suitable for hair conditioners / alkylamines, alkylimidazolines, quaternary ammonium compounds), AMPHOTERIC (the surface-active part of the molecule can be an anion in alkaline or a cation in acidic conditions / phospholipids, alkyl betaines, alkylamidopropyl betaines).

COSMETIC PRODUCTS THAT CLEAN SOLUBILIZING: hydrogels, foams, soaps, micellar waters.

COSMETIC PRODUCTS FOR DISSOLVING SKIN CLEANSING: oils, cleansing milks, cleansing creams, chemical peels, enzymatic peels.

COSMETIC PRODUCTS THAT CLEAN ABRASIVELY: classic mechanical or physical exfoliation, microdermabrasion.

COSMETIC PRODUCTS THAT CLEAN ADSORPTIVELY: clay masks

HYDROGELS: designed for cleansing oily or impure skin / have a moisturizing effect, successfully remove excess sebum and prevent excessive shine of oily skin / besides SAS, they also contain antiseptics (inhibitors of bacteria multiplication) and astringents (pore tighteners).

FOAMS: contain many synthetic SAS and effectively cleanse / the face must be moistened before application and the residue thoroughly rinsed / suitable for normal to combination skin, but not recommended for use on dry and sensitive skin.

SOAPS: modern soaps contain alkali salts of higher fatty acids and syndets, contributing to less damage to the skin's hydro-lipid film / classical soaps are exceptionally used for skin cleansing / they excellently remove sebum, but with their alkalinity burden the skin, which needs to regulate the acidity of the hydro-lipid layer - more suitable for oily and impure skin.

MICELLAR WATERS: newer products are ethanol-free, with a high percentage of moisturizers, mild SAS, anti-inflammatory agents (act against inflammation, soothe irritated skin), preservatives, and are appropriately scented and suitable for all skin types.

OILS: oil-based solutions are intended for removing makeup, often long-lasting. Often, the base is liquid paraffin, to which natural waxes and oils are added. Since it creates a thin film, emulsifiers are added to facilitate oil removal. Natural oils are becoming increasingly popular.

CLEANSING MILKS: are O/V emulsions. The fats in the milk remove lipophilic impurities, and the water phase removes hydrophilic impurities. In composition, they are similar to care products, but because they have added SAS, they have good cleaning properties (but do not foam). They are rinsed with water due to the external water phase. The remaining layer on the skin acts emolliently and prevents moisture loss. For additional action, they contain various plant extracts, antioxidants, alpha-hydroxy acids...

CLEANSING CREAMS: suitable primarily for cleaning dry skin. They do not contain water - a mixture of oils and waxes, fatty alcohols, solid paraffin, SAS, enabling the cream to be rinsed.

CHEMICAL PEELING: only surface peeling is used, which removes dead cells and improves the condition of acne-prone skin (non-inflammatory acne), aging skin, and minor irregularities in hyperpigmentation and pore tightening. The most well-known are AHA and BHA acids (more on this in the next post).

ENZYMATIC PEELING: also suitable for sensitive and dry skin. Bromelain from pineapple, papain from papaya, actinidain from kiwi, and fikain from fig are used. All are proteolytic (participate in the breakdown of proteins) enzymes, and bromelain also has anti-inflammatory effects.

MECHANICAL OR PHYSICAL EXFOLIATION: The most straightforward to use. The base can be a cream or hydrogel in which fine solid particles of sodium tetraborate decahydrate, polyethylene silica gel, aluminum oxide, fine sea sand, loofah, ground apricot kernels, olives, etc., are evenly distributed. With gentle circular motions, guide the solid particles over its surface and slowly polish it. Always perform it after prior skin cleansing with cosmetic products containing SAS, so that fat-soluble impurities have already been removed.

MICRODERMABRASION: A type of mechanical exfoliation. Through a nozzle under increased pressure, they spray tiny crystals that peel off dead cells. It is used for wrinkles, scars, stretch marks, and for accelerated skin renewal.

CLAY MASKS: Various clays can be used - kaolin, fuller's earth, bentonite, Rasul clay. They are suitable for all skin types, but on dry skin, leave them on for a shorter time. They excellently absorb excess sebum, cleanse pores, and are often used for acne-prone skin.

SOURCES:

Nina K.G., Damjan J., Mateja L., Katja S., Meta K., Eva T. B., Mirjam G., Helena H., Mirjana G., Mojca L., Saša B., Sodobna kozmetika : sestavine naravnega izvora. 1.izd - Velenje: Širimo dobro besedo, 2015

Svoljšak Mežnaršič, Irena, Kozmetični izdelki: (učbenik za modul Kozmetični izdelki v izobraževalnem programu Kozmetični tehnik, 1. natis. - Ljubljana : Grafenauer, 2015

POVRŠINSKO AKTIVNE SNOVI (v nadaljevanju PAS): čiščenje kože na obrazu je temelj vsake nege - le dobro očiščena koža lahko sprejema kozmetično aktivne sestavine

• PAS so molekule, ki imajo lipofilni in hidrofilni del

• izdelki morajo ohranjati zdrav mastno-kisli plašč (hidrolipidni film), ki zadržuje nivo vlage v koži

• ne smejo poškodovati bariere kože, ne sme poškodovati hidrolipididnega zaščitnega filma, ne sme dražiti kože in mora ustrezati tipu in stanju kože

• delimo jih glede na podlagi njihovega izvora (naravni in sintetični) in vloge v kozmetičnih izdelkih (protipenilci, emulgatorji tipa V/O in O/V, močljivce, solubilizatorje, detergente), mehanizma delovanja in njihovega obnašanja v vodnem mediju (glede na disocijacijo med raztapljanjem v vodnem mediju in sicer ločimo neionogene PAS (ne disociirajo v vodi) in ionogene PAS (kationske, anionske, amfoterne in v vodi disociirajo)

• NAČINI POVRŠINSKEGA ČIŠČENJA KOŽE: solubilizirajoče (temelji na na uporabi PAS, ki se jih dodaja v čistilne izdelke za kožo, zato, da bi se izboljšal stik med lipofilnimi nečistočami na koži in hidrofilnim vodnim medijem čistilnega sredstva. Molekule PAS ob nanosu tvorijo micele, v katere se ujamejo lipofilne nečistoče in to omogoča mešanje lipofilnih nečistoč z vodnim medijem in posledični njihovo odstranitev s površine kože), raztapljajoče (temelji na raztapljanju lipofilnih nečistoč v lipofilnem oljnem mediju, ki ga uporabimo kot čistilno sredstvo), adsorptivno (so čistilne maske, ki vsebujejo prah, kot so kaolin, fulerjeva zemlja, pšenični klej, izvleček pšenične moke...; po nanosu na kožo voda izhlapi iz iz maske, polimer pa tvori na površini kože film, v katerem ostanejo ujeti prašni delci, ki potem vlečejo ven lipofilne nečistoče iz kože), abrazivno (mehanski piling, mikrodermoabrazija)

• emulgatorji so povezovalni člen vodne in lipidne faze kozmetičnih izdelkov - omogočajo nastanek stabilnih emulzij - in na podoben način delujejo PAS za čiščenje, saj povečajo topnost v vodi

• tip emulzije je odvisen od PAS, od razmerja obeh faz in postopka izdelave emulzije

• emulgator, ki ima prevladujoč lipofilni del in se topi v lipofilnem mediju, tvori emulzije tipa V/O (VODA V OLJU) in obratno: emulgator pri katerem prevladuje hidrofilni del in se raztaplja v vodi, tvori emulzijo tipa O/V (OLJE V VODI)

• izbor naravnih emulgatorjev je izjemno skromen

• značilno je, da se urejajo na medfaznih površinah (npr. med oljno in vodno fazo, med disperznim medijem in suspendiranimi trdnimi delci) in povzročajo padec medfazne napetosti

• NEIONOGENE PAS: združljive so z večino sestavin kozmetičnih izdelkov, dobro čistijo, so dobri solubilizatorji in dobri emulgatorji, vendar se šibko penijo

• IONOGENE PAS: ANIONSKE (v vodi disociirajo, površinski aktivni del molekule je anion, ionski deli pa so lahko karboksilat, sulfat, sulfonat, fosfat / mila, alkisulfati, alkiletersulfati), KATIONSKE (v vodi disociirajo, površinsko aktivni del molekule je kation; ne čistijo dobro in se ne penijo bogato, primerni so predvsem za regeneratorje las / alkilamini, alkilimidazolini, kvarterne amonijeve spojine), AMFOTERNE (površinsko aktivni del molekule je lahko anion v alkalnem ali kation v kislem / fosfopidi, alkil betaini, alkilamidopropil betain)

• KOZMETIČNI IZDELKI, KI ČISTIJO SOLUBILIZIRAJOČE: hidrogeli, pene, mila, micelne vodice

• KOZMETIČNI IZDELKI ZA RAZTAPLJAJOČE ČIŠČENJE KOŽE: olja, čistilna mleka čistilne kreme, kemični piling, encimski piling

• KOZMETIČNI IZDELKI, KI ČISTIJO ABRAZIVNO: klasični mehanski ali fizikalni piling, mikrodermoabrazija

• KOZMETIČNI IZDELKI, KI ČISTIJO ADSORBTIVNO: glinene maske

HIDROGELI: namenjeni so čiščenju mastne oz. nečiste kože / imajo vlažilni učinek, uspešno odstranijo presežek sebuma in s tem preprečijo prekomeren sijaj mastne kože / poleg PAS vsebujejo tudi antiseptike (zaviralci razmnoževanja bakterij) in adstringente (zooževalci por)

PENE: vsebujejo veliko sinteznih PAS in učinkovito čistijo / obraz mora biti navlažen preden jo nanesemo in preostanek temeljito speremo / primerne za normalno do mešano kožo, odsvetuje pa se uporaba na suhi in občutljivi koži

MILA: sodobna mila vsebujejo alkalijske soli višjih maščobnih kislin in sindete, kar pripomore k manjši poškodbi kožnega hidrolipidnega filma / klasična mila se izjemoma uporabljajo za čiščenje kože /sicer odlično odstranijo sebum, vendar s svojo bazičnostjo obremenijo kožo, ki mora uravnavati kislost hidrolipidnega sloja - bolj primerna za mastno in nečisto kožo

MICELNE VODICE: novejši izdelki so brez etanola, z visokim deležem vlažil, blagimi PAS, antiflogistiki (delujejo protivnetno, pomirjajo razdraženo kožo), konzervansi in so primerno odišavljeni ter primerni za vse tipe kože

OLJA: oljne raztopine so namenjene odstranjevanju ličil, velikokrat tudi dolgo obstojnih. velikokrat je osnova tekoči parafin, ki so mu dodani naravni voski in olja. Ker naredi tanek film, so dodani emulgatorji, ki olajšajo odstranjevanje olja. Vedno bolj pa so priljubljena tudi naravna olja

ČISTILNA MLEKA: so emulzije O/V. Z maščobami v mleku odstranimo lipofilne nečistoče, z vodno fazo pa hidrofilne nečistoče. Po sestavi so podobni negovalnim izdelkom, ker pa imajo dodane PAS, imajo dobre čistilne lastnosti (se pa ne penijo). Spirajo se z vodo zaradi zunanje vodne faze. Zaostali sloj na koži deluje emolientno in preprečuje izgubo vlage. Za dodatno delovanje vsebujejo različne rastlinske izvlečke, antioksidante, alfa-hidroksi kisline...

ČISTILNE KREME: primerne so predvsem za čiščenje suhe kože. Ne vsebujejo vode - zmes olj in voskov, maščobnih alkoholov, trdni parafin, PAS, ki omogočajo spiranje kreme.

KEMIČNI PILING: uporablja se samo površinski piling, ki odstrani odmrle celice in izboljša stanje aknaste kože (nevnete akne), starajoče kože in manjše nepravilnosti v hiperpigmentaciji ter za zoožanje por. Najbolj poznane so AHA in BHA kisline (več o tem v naslednji objavi)

ENCIMSKI PILING: primeren je tudi za občutljivo in suho kožo. Uporabljata se bromelain iz plodov ananasa ter papain iz papaje, aktinidain iz kivija ter fikain iz figovca. Vsi se proteolitični (sodeluje pri razgradnji beljakovin) encimi, bromelain pa ima tudi protivnetno delovanje

KLASIČNI MEHANSKI ALI FIZIKALNI PILING: najbolj enostaven za uporabo. osnova je lahko krema ali hidrogel v katerem so enakomerno razporejeni fini trdni delci iz natrijevega tetraborata dekahidrata, silikagela polietilena, aluminijevega oksida, finega morskega peska, lufe, zmletih koščic marelic, oljk... / z nežnimi krožnimi gibi vodimo trdne delce po njeni površini in jo počasi brusimo. Vedno ga izvajamo po predhodnem čiščenju kože s kozmetičnimi izdelki s PAS, tako, da smo že odstranili v maščobi topne nečistoče

MIKRODERMOABRAZIJA: je vrsta mehanskega pilinga. Skozi šobo pod povečanim pritiskom razpršijo drobne kristalčke, ki odluščijo odmrle celice. Uporablja se za gube, brazgotine, strije in za pospešeno obnavljanje kože

GLINENE MASKE: lahko se uporabljajo različne gline - kaolin, fulerjeva zemlja, bentonit, rasulova glina / primerne so za vse tipe kože, le da jo na suhi koži pustimo delovati krajši čas. Odlično adsorbirajo odvečni sebum, očistijo pore, zato se pogosto uporablja za aknasto kožo

VIRI:

Nina K.G., Damjan J., Mateja L., Katja S., Meta K., Eva T. B., Mirjam G., Helena H., Mirjana G., Mojca L., Saša B., Sodobna kozmetika : sestavine naravnega izvora. 1.izd - Velenje: Širimo dobro besedo, 2015

Svoljšak Mežnaršič, Irena, Kozmetični izdelki: (učbenik za modul Kozmetični izdelki v izobraževalnem programu Kozmetični tehnik), 1. natis. - Ljubljana : Grafenauer, 2015