# What reaction makes sodium silicate harden in CO2

I have looked all over the web, and I can only find information stating that it does happen. I don't doubt that I just can't figure out what is happening. Some sources state that an acid can cause the hardening others say heat causes the hardening so my speculation would be that the water needs to be driven out for the heat to work, but I don't have a clue how the other to work. And it would imply that there are multiple routes for their reaction addition of water versus editions of some part of some acid versus addition of $$\ce{CO2}$$ so you should have all kinds of different reactions... or not what do I know?

An ancillary question: when is water soluble and when it is not I found some obscure commenters on I think Reddit speculating the it's solubility would have something to do with how it was hardened. I also found on its Wikipedia page an ambiguous and Trey saying something about solubility and more seems to say that different types or ratios have different solubilities. Unfortunately I didn't collect any links and I feel like my research was so sporadic and Scattered that it would only Hinder.