I often get requests for special -or- richer nighttime moisturizers. Being so thin, the epidermis can only absorb so much, and the remainder of any product that is heavily applied, only sits on the surface of the skin.
If you think of the epidermis as a cup, you can only fill it so full. Consider why you are prescribed a careful homecare regimen. Once you apply your hydrator, serums, .Vitamin C, and finish with an appropriate moisturizer, your skin "cup" is 'full'.
The majority of all professional skincare actives (pharmacological quality, in high levels) penetrate to the junction between the epidermis & the dermis. Cheaply made, and most OTC products don't have enough
Text Link "actives" in them to really have any positive effect on the skin).
Good quality moisturizers provide special esterified (absorbable) fatty acids, emollients, and ceramides that will gently penetrate the epidermis.
OTC moisturizers have more nose-appeal and packaging-appeal, but are loaded with heavy waxes, inexpensive oils, and very high levels of silicones and silicone derivatives in them to provide that silky (but non-nutritive/non-beneficial effects) feel.
Because mass-marketed moisturizers are so fluffed-out with acrylic gelifiers to give them bulk (instead of filling them with the good substances mentioned above), they require a lot more water to make the finished product. The more water and gel-making substances in an OTC product - the less quality- ingredients are included, and more heavy preservatives are needed due to the amount of water and extended time is sits on a store's shelf.
Remember: Some fatty acids and ceramides from a moisturizer are slightly absorbed into the epidermis (top layer), but its main function is to provide a barrier between the skin and environment, and to protect it from the evaporative effects of TEWL - Trans-epidermal-water-loss. Thus, the requirement to hydrate first (hyaluronic acid is best); then apply your water-based serums, and follow it with the correct moisturizer.
Thick, heavy, greasy layers of moisturizer can do more harm than good. It can notoriously bind with the dead/dull surface cells and create the ideal environment for acne if you are prone to it; and create a tenacious layer of dead gluey cells clogging & dilating your pores by filling them with waxy plugs; making you look dull, have uneven tone & texture, and increase the appearance of existing wrinkles.
Final thoughts: While there might be special circumstances in which the skin requires an occlusive barrier (lots of swimming, skiing, prolonged exposure to wind, and cold/dry temperatures), the skin should never be covered with thick occlusives.
Professional quality skincare products have such high levels of actives, you need not apply them heavily. Layer as directed, and don't over-fill your skin's "cup".
Invest in synergistic products: hydrators, serums, and a good quality moisturizer specific for you skin type & condition. Thick layers of anything applied to the skin are wasteful and have the potential to create more problems long-term.
(and...WHY MORE ISN'T BETTER)
The epidermis is the outermost layer of the skin. Categorized into five horizontal layers, the epidermis actually consists of anywhere between 50 cell layers (in thin areas) to 100 cell layers (in thick areas). The average epidermal thickness is 0.1 millimeters (0.0039 inches), which is about the thickness of one sheet of paper. Beneath the epidermis, is the dermis, and it is about 2mm (0.079) thick.
The dermis is where the meshy network of your foundational or structural scaffolding support systems of the skin reside. Those structural proteins are called collagen and elastin. Throughout the dermis are blood vessels, lymph vessels, nerves, and mast cells. Mast cells are play an important role in triggering the skin's inflammatory response to invading microorganisms, allergens, and physical injury. Beneath the dermis lies the fat which acts as a cushion, temperature-regulator, and provides shock absorption. Fat cells also store nutrients and energy.