I started brewing beer in 1999 using some of my dad's carboys when he used to make wine. They have to be at least 50 years old. I really never gave a thought to the construction of carboys and the possibility of the bottom falling out but I have recently seen some articles and videos about this very topic. The bottom of their carboys simply fall off for no apparent reason. One video I watched was very informative and came to the conclusion that Italian made carboys are the best. Carboys made in Mexico not so good. It has to do with the quality of the glass and the cooling process of the hot glass. Bubbles in the side walls can also be a problem. Over the years I have noticed bubbles on the sides of some of those 50 year old carboys and wondered if they could be a problem. Apparently they could be but like I said I have used them for a very long time. I only have two empty carboys right now and they were both made in Italy. I'll have to inspect the full carboys at my next racking. Was wondering if any of you folks had carboy bottoms fall out or are even aware that this is a problem.