# How does lime prevent soda lime glass from dissolving in water?

How does lime addition as an ingredient prevent soda lime glass from dissolving in water? Does it form calcium silicate in the process of melting?

The difference is in the crystalline structure. Silica ($$\ce{SiO2}$$) consists of silicon atoms bridged by oxygen atoms, forming a periodic crystal with no net charges on any atom.
However when some alkali is introduced ($$\ce{Na2O}$$), the additional oxygen atoms remain charged, and cannot link silicon atoms together; those form silicate anions. The silica breaks and depolimerizes, and the remaining $$\ce{Na+}$$ fill holes in the structure to maintain charge balance. Thus the solid melts at lower temperature with reduced viscosity, it's "more fluid".