Eli5 how come glass bottles have seams aren’t they made in one peice?

Question

Eli5 how come glass bottles have seams aren’t they made in one peice?

In: Technology

Answer 1

Usually the seams are an artifact of the mold. The mold is two pieces of metal that you put together to form a 3D shape like a bottle. When you pull the mold off the glass, the seams are left where the metal comes together.

Answer 2

I think the seams make the glass more turgid/stronger. Without them, the glass would simply shatter.