Despite a lot of interest cleansing techniques it is rare to hear of the techniques of stomach cleansing. Perhaps this is due to them being part of traditional yoga cleansing practised by very few people.
The simplest technique is one that is practised first thing in the morning before breakfast!
It is called vamana dhauti although you might find it called kunjal and it consists of drinking 8 or 9 glasses of salty water which of course will bring on a feeling of nausea and likely will produce a vomiting reaction and the entire contents of the stomach will be emptied.
Voila – stomach cleansing achieved!
I do not recommend this traditional technique although it is basically not that different from using a Neti pot or doing colonics or using an enema.
There are variations on this stomach cleansing technique and again I do not recommend them! One is to swallow inch by inch either a narrow strip of bandage or a narrow rubber tube. It takes quite some practise to be able to swallow several feet of either. After some time the bandage or tube is removed and rinsed and the stomach has had some mucus etc removed and is declared cleansed.
I have a life long devotion to yoga and have never delved into these traditional "purification" or cleansing techniques. Real yoga is about meditation and living the right lifestyle and these techniques are in my opinion pranks and are rightly all in the history books and I think that is where they should stay.
The goal stomach cleansing can be achieved like all organs in the body by modern Naturopathic treatment including a high quality vegetarian diet including lots raw juices and natural fibre.