A Twitter friend asks what an astringent is. And the answer is basically quite straight forward on one level. It is something that stings the skin and stimulates it to react. The easiest way to think about it is to consider the material that is most often used as an astringent, or at least most often used in conjunction with the word astringent, which is witchhazel. If you know what witchhazel does, then that is an astringent. The main experience I have had of witchhazel was having it applied to wounds and bruises as a kid. I was told then that it would clear away the germs and stimulate the skin so that the wounds or bruising would heal more quickly.
When you are that age you tend to believe whatever you are told by adults. Looking back with a more sceptical frame of mind, I am not sure how well established this activity actually is. But the theory sounds good. It is definitely the case that we all have very effective built in protection and repair mechanisms that deploy a number of activities to stop small cuts turning into major infections. The immune system is the first line of defence. This operates via the white blood cells which are continually on patrol looking for anything out of the ordinary. When they locate foreign proteins or other abnormal intrusions they react straight away. I find it very easy to believe that whacking something that the body is going to react to anyway on the skin is going to help that process. It is a bit like sounding the alarm.
Astringents also get used in cosmetics where the idea is basically the same one of triggering a reaction from the body’s immune system. This is likely to lead to an increase in blood flow and oxygen supply to the treated area and generally stimulate all the body’s normal processes for keeping the skin in order.
Again, I don’t think this is a process that has been studied in much depth or which has led to any particular conclusions that can be drawn. But I find it quite easy to believe that it would work. The best way to find out if it works for you is to give it a try.