The first reason is to avoid the uneven bottom of the glass bottle and unstable placement.
For glass products such as wine bottles, the previous crafts were hand-blown. If you want to make the bottom a whole plane, then as long as there is a little unevenness or deformation, the whole bottle will not stand stably. The technology at that time would inevitably lead to many glass bottles being unstable and increasing the scrap rate. Nowadays, the bottom of most glass bottles is designed to be concave to solve the problem of unstable standing. There is only an outer circle where the bottle with a depression touches the ground. Even if the circle is not very flat, the bottle can easily stand firmly according to the principle of three-point support.
The second reason is that the liquid itself exerts pressure on the bottom of the glass bottle.
The higher the liquid level in the bottle, the greater the pressure that the liquid exerts on the bottom of the bottle, thus forming a downward pressure that acts evenly on the bottom of the wine bottle. If the bottom of the bottle is made into a smooth plane, the bottom is easily bulged out by the pressure of the liquid, so that the glass bottle cannot stand steadily. Therefore, people process the bottom of the glass bottle into a concave shape in order to increase the contact area between the bottom of the bottle and the liquid and reduce the pressure.
Edit by Changsha Aikeyi Homeware Co.,Ltd