A cleanser is one which removes dirt, sweat, sebum, micro-organisms (bacteria etc.), dead cells (stratum corneum) and make-up if used from the skin surface.

Cleansing comprises of three stages:

1. Wetting.
2. Emulsification and removal of grease.
3. Rinsing. 

Deeply ingrained dirt, particularly in the pores of the hair follicles and sweat glands can be removed by warming the skin with hot water or a mild steam bath.

Normal pH of the skin is 4.5 to 5.5, this acidic pH changes to alkaline due to application of cleanser and gives a feeling of freshness in the skin.

Types of cleansers:

• Soaps and cleansing bars: They are derived from fatty acids and tri-glycerides (fats and oils).
  1. Routine bars.
  2. Deodorant or anti-microbicidal bars:
      These have an added anti-bacterial agent to eradicate bacteria. These soaps have a pH between 9 - 10 and may cause skin irritation. They are good for oily skin.
  3. Moisturising base:
     These have moisturising agents like lanolin or glycerin. Their pH is between 5 - 7, thus they are non-irritant. They are good for dry skin.
     
     Functions: Soaps help cleansing, perfume the bath, softens the water, forms lather and gives the skin a cool and fresh feeling. 

• Lipid free cleansers / Face wash:
    These contain water, glycerin, cetyl alcohol and do not contain any fat. They clean without soap formation and leave a thin moisturising film. They are good for sensitive and photo aged skin.
• Cleansing creams:
    They are oil based products which remove grease and cosmetics on the skin by dissolving it in more oil. They are good for dry skin.
• Cleansing Lotion:
    It is a water based product and is good for normal and dry skin. Since it is water based,it can be easily rinsed with water. It is commonly sold as pore cleanser.
• Exfoliants:
    Help in removing dead cells (stratum corneum cells) from the skin.
• Abrasive scrubs:
   They aid in removing dead cells and control excess sebum secretion. They are mechanical exfoliants made of granules in form of Aluminum oxide, ground fruit pits etc.
• Cleansing masks / packs:
  Setting masks - containing Fuller's earth ('Multani Mitti').
  Peel-off masks - containing gel and latex.
  Non-setting masks - containing cold cream or oil packs.

Setting and peel-off masks achieve cleansing, exfoliation and skin-tightening. They also refresh the skin. Non-setting masks only clean the skin.