Using baking soda to exfoliate is a good idea.
Although this is a common idea in the internet, it is best avoided. Why? Because when mixed with water (this is the recipe usually recommended) you get an alkaline substance (pH> 7). The pH of the skin is between 4.5 and 6.5, so slightly acidic ... and it is important that it stays there! The pH of cosmetic products is therefore very important and must be monitored and tested to avoid disturbing the acid barrier of the skin. You see us coming ... using baking soda mixed with water, without testing its pH, we risk (read it) to disturb this barrier, and create more harm than good (irritation, redness, increased dryness, etc.). If we test the pH, do you say? Try it ... we would be surprised if you reach a "safe" pH only with these two substances! ;)
So, we keep it for biscuits and cakes ... and if we want to exfoliate ... we opt for other types of scrubs.
Yosipovich G, Tur E, Cohen O, Rusecki Y: Skin surface pH in intertriginous areas in NIDDM patients: Possible correlation to candidal intertrigo. Diabetes Care 1993; 16: 560-563.