Third domino
Waterglass, geopolymers

What is waterglass?

This substance is again a white powder, with the chemical formula Na2SiO3, and it's produced when natron (Na2CO3) breaks down the quartz (SiO2) in the given material.

It extracts the silicon from the stone and assimilates it. It eats quartz for breakfast, while it belches out CO2.

Na2CO3 + SiO2 = Na2SiO3 + CO2

What are the properties of waterglass?

Dry waterglass slowly dissolves in water, where it breaks down into sodium ions and silicate ions. In this form, it serves as an excellent paper adhesive.

But if it encounters metal oxides, it shows its real strength: it stimulates them to form various metal silicates, precursors of stones. If you drop different materials into waterglass solution, you'll get this colorful underwater(glass) forest.

Did someone say stone?

Geopolymers

If we look more closely at what else waterglass is good for, we quickly realize its real potential.

We have only known since the 1970s that waterglass can be used to create a substance similar to, but harder than concrete, and that doesn't require cement. Moreover, this material can be successfully used in 3D printers, allowing us to "print" houses with it.

The collective name for these materials is geopolymer.

Ancient geopolymers?

If we look at ancient stone structures, we can find a million examples where our ancestors somehow softened the stones and worked with them like children playing with clay.

They bent the stones, pressed their hands into them, carved them with knives, or even molded a clumsy little monkey onto them.

In the bottom right corner, it's evident that someone carved out the puma. But the little monkeys look like they are from a different material.

Artificial stone

And what a surprise! This is exactly how you can work with waterglass-based artificial stones, the geopolymers. After mixing, they are just like play-doh. An hour later, they start to harden but can still be cut with a knife. After a day, they become as hard as rock.

But why is it black? Waterglass is transparent, right?

How to make a stone?

Let's be lazy and try to add the material that's already piling up as waste, since we've melted the stone with fire: wood ash*.

Let's add some water. You get the play-doh above. And after 24 hours you'll have an artificial stone. Or your own Excalibur. BINGO!

*Not just any wood ash. Pine wood ash is the best containing high amount of aluminum oxide.

Any proof of ancient waterglass use?

Returning to the original mural, we can see a white pile of something accumulating in the background. That something is contaminated with black specks.

Of course, it's contaminated because it's mixed with the remaining charcoal. Then this white substance is carried around in bags, poured out, and someone molds a wall out of it.

All this is depicted in a singe mural (of smelting metal)!
Every ancient civilization with access to natron (or similar alkali material like wood ash lye) knew how to make waterglass. We see evidence of this everywhere (scoopmarks). And undoubtedly, they had access to wood ash. The question is whether they tried to mix the two. If they did, they could have created artificial stone. Let's recap what we know so far: