Exfoliation is defined as removing dead cells by either using chemical or mechanical methods.
Mechanical uses physical things like ground up walnut shells, sand, sugar, or other material while chemical is something like the sour milk used historically. It is usually a liquid or a paste.
Your body automatically sheds skin cells approximately every 30 days but skin cells don't always fall off and when this happens your skin acquires dry flakey patches or end up with clogged pores.
Exfoliation, when done properly and regularly, is good for your skin. It can leave your skin look brighter, and help your skin absorb skin products. In addition, exfoliation can help eliminate clogged pores which means fewer breakouts. Furthermore, if exfoliation is done over a long period of time, your collegian production increases so your skin increases its elasticity, reduces fine lines, and decreases sagging.
When looking at a mechanical exfoliation, it could be a cleaning scrub, a small brush, sponge, glove, or a loofa. You can buy a nice cleaning scrub or make your own. I've used a nice foaming cleanser with a mild abrasive that did a nice job of cleaning my skin. Unfortunately, if the mechanical scrub is used incorrectly, it can irritate your skin or cause trans epidermal water loss.
As far as chemical exfoliation, it might be something like Alpha hydroxy acids (AHA) such as glycolic acid from sugar cane, lactic acid from milk. AHA's are good for removing fine lines, help with age spots, and uneven skin tones. Another possibility is Beta hydroxy acids (BHA) which is oil soluble and goes deep into your skin to treat acne and can also be used to treat sun damage.
There is also the popular retinoids or retinal. These keep your skin safe from free radicals while promoting collagen production.
It is recommended that if you have dry skin, you should avoid mechanical exfoliation because it could cause micro tears. It is better to use AHA's such as glycolic acids because it helps remove dead cells and encourages healthy skin turnover. If your skin is normal, any method of exfoliation works well. On the other hand, if you have oily skin, it is better to use a mechanical exfoliation such as brushes. If you have sensitive skin, try to use gentle chemical exfoliation but if you have a combination skin, one needs to use both mechanical and chemical exfoliation. It is strongly recommended you use mechanical one time and chemical another time but never on the same day or at the same time.
When you buy a scrub, make sure it's designed for your face and not your body because those made for the body are often harsher and can rip up the delicate face skin. Since there are a lot of choices, it is recommended that you use only one problem at a time otherwise, your skin might react. If your skin changes, be willing to change product to meet the new needs of your skin. Let me know what you think, I'd love to hear. Have a great day.