It depends on the ingredents in the products used that'll help determine how well it may be absorbed or not. Or if mixing can cause risk for certain ingredients to become inefective. For example:
Effectiveness:
Natural vitamins are beneficial to the skin. Yet, vitamin C as a topical application (such as in lotions, cremes, gels, etc) risks degradation from air exposure...especialy when being mixed. Vitamin E and C, is also beneficial, yet can hardly be used in their natural form (topically), since air exposure immediately and dramatically weakens the vitamins' potency.
Combination of Ingredients:
Some products use an
AHAs (alpha hydroxy acids) as the active ingredient, while others use
Retinol. Both have anti-aging effects. However, the reason these two ingrediets are not used in the same products together is that together they become innefective. Likewise,
vitamin C (L-ascorbic acid) and
glycolic acid also cancel out each other's functions and benefits when used together. Most people don't have this kind of prior knowledge (including myself), and may wind up wasting money and time with innefective combinations. Other combinations can also lead to bad reactions in the skin.
[You must be registered and logged in to see this link.]Mineral Oil:
A main ingredient in baby oil, it's popularly used because it is cheap and doesn't spoil. it's a byproduct of distallation of gasoline from crude oil, in otherwords it's leftover liquid. It's difficult to absorb and clogs the pores and it sits on the surface of the skin in a thin layer. Once it's absorbed through the skin, it is broken down by the liver and passes through the intestinal tract. And then will absorb all of the fat soluable vitamins (such as A, D, E & K) from the body.
[You must be registered and logged in to see this link.]Not saying that products will become completely inefective. But, it's potential in comparison with non-mineral oil based products may may differ and good to keep this in mind. I'm using Nadinola now, 3rd day I think, and I looked on the label and one of it's main ingredients is mineral oil. But, many people say they receive good lightening from it so it's worth a shot...it still makes me wonder how much more potent it could be if the mineral oil was replaced with hemp oil or almond oil? Although I prefer to avoid products that contain mineral oil, if a product has good reviews I may be willing to give it a shot if it'll help me to reach my goal.
There are so many ingredients, and which igredient makes the other less effective I still have a longs ways to learn as I'm sure there are many. And when mixing, you'll have to take into consideration of air and light exposure when mixing, can decrease certain ingredient's effectiveness. Such as for products that contain Hq, vitamin C (ascorbic acid), retinol, etc. The skin products mixed together can become more potent or less effective, it is based on trial an error and you'll never really know how well it may or may not work until you have tried it.