Pompeii fixed potholes with molten iron (2019)

I believe this is the article:

https://www.ajaonline.org/article/3863

> In July 2014, we conducted a survey of Pompeii’s street network to document traces of iron that were observed on the stone-paved streets, which resulted in the identification of 434 instances of solid iron and iron staining among the paving stones. ... Pompeians were—in addition to using solid iron wedges—pouring molten iron and iron slag onto their streets as a method of emergency repair.

There's a huge gulf of difference between "a civilization is capable of melting iron" and "molten iron is so cheap and easy they used it to fill potholes".

Castable iron: Valuable, scarce, energy intensive, very hard to melt (comparatively), corrodes readily (especially on the coast)

Iron and other metal slag: Byproduct of iron smelting, basically waste, melts fairly easily, was used as ballast in ships, comparatively cheap, rusts superficially but is mostly a matrix of oxides which don't meaningfully react

I'm beyond skeptical that perfectly good cast iron was used to fill potholes. Using slag/dross/failed smelts/other byproducts of metallurgy makes far better sense.

It would be like far future archeologists unearthing rammed earth tire walls and concluding "the 20th century was so efficient at producing rubber they used excess tires as a building material" vs "they used a waste product which would have been landfill anyways".

I am somewhat sceptical, as iron was very expensive back then. And they do not come up with a working idea how they possibly could have done it in an economic way. Portable smelters were not really a thing. And building an oven next to every hole does not sound too practical either. At least not easier, than just fixing the holes with stones.

Also shouldn't we have found other instances, where it was done?

"The researchers found that repairs using liquefied ore were being carried out just before the city’s destruction."

So my first (uneducated) guess would rather be, that hot lava might have tampered with the evidence.

This article is incorrect. The actual claim is that the romans were making repairs with molten ore, ie slag, which has a substantially lower melting point than molten iron and would be a cheap byproduct of iron production.

Unless I'm mistaken, this strikes me as a really incredible claim. To the best of my knowledge, Rome didn't make much use out of cast iron. Iron has a very high melting point, it's not something that people were just casually melting. There were a few exceptions, but my understanding is that Europe mostly didn't use cast iron until late in the middle ages.

The idea that some random resort town was casually melting iron and hauling it around to fill cracks strikes me as really implausible. Some other, more easily melted metal perhaps, but not iron. Not unless my understanding of Roman metallurgy is really mistaken.

I'm currently reading a book about Cleopatra [1] (it's superb) and I've been absolutely boggled by the productive capacity of the nation states of her era. Whether it was building ships, growing and transporting grain or raising armies, these were highly sophisticated bureaucracies that knew how to make, grow and transport huge quantities of stuff.

I'm at work and don't have the book on me, so I may have this slightly wrong, but IIRC, in Cleopatra's day Alexandria (where she resided with her court) was consuming 300 tons of grain per day, which arrived on ships via the Nile. Or consider the ability of Rome to draft and train legions of highly-skilled soldiers: it was at a scale similar to that of modern-day Russia.

1: https://www.goodreads.com/book/show/7968243-cleopatra

I do find this quite hard to believe. Iron would be considered an expensive material to use in roadbuilding even today. The pictures aren't all that convincing.

> But lead author Eric Poehler of the University of Massachusetts Amherst writes that stray iron drops found on the street suggest that the molten metal was carried from a furnace to the repair site.

If the hypothesis is that they were capable of carrying molten metal from a furnace to the road, isn't it more likely that these are splashes or spills from molten iron en route to a blacksmith?

> most of the streets in the bustling seaside city were paved with silex, a type of cooled lava stone

'silex' is a rather old-fashioned word; nowadays it's more commonly called 'flint', which is a sedimentary rock, not an igneous one. https://en.wikipedia.org/wiki/Silex

> processing taconite, a type of low-grade iron ore

taconite is typically 30%–35% iron, but it's true that most iron has historically been made from higher-grade ores than that (though throughout history iron has usually been made from lower-grade ores, just in much smaller quantities)

it is indeed fairly surprising to find cast iron in a roman town. china had cast iron from around 2500 years ago, but i thought the technology only reached europe during medieval times, and even later in western europe

Count me as skeptical as well. Not only would it have been wildly impractical, but iron is prone to rusting and expands when it rusts. Plus it is slippery when wet. It's just not a good pothole filler.

I wonder if this was just the doings of some eccentric in an act of euergetism (the wealthy supporting their cities through public works and the like) who thought that iron was just the thing. It was a resort city that attracted a lot of rich folk. It seems possible that rather than giving us insight into how the Romans maintained their cities it is just unveiling some small interesting idea someone brought into reality.

It is unlikely we'll ever know for sure. But it is interesting to contemplate how much of what we think we know about the past could be just way off and we've invested too much into artifacts of odd occurrences that just happened to survive while the more mundane and "real" are lost to time.

Call me sceptical.

That would have been astronomically expensive given the enormous supply chain needed to produce charcoal to get that iron in those times.

I am sceptical on how they figured out iron stains are pothole fillings. I think much simpler explanation would be everyday items or metal pieces of carts getting stuck between stones.

They lived in really nice villas too. Frescos on the wall and mosaic floors. Better constructed than modern ones in some regards. No sqeeky floors for example. Surrounded by organic gardens with lemons and oranges and fragrant spices

Badass article, super cool to think about filling pot holes with molten iron. Visited Pompeii with family when younger and one of the few things I remember “experiencing” were the wheel ruts while walking around. Very much makes sense now how difficult it’d be to fill in given the depth and width of the ruts; they’re expansive. Am not familiar with iron making but curious about iron slag. Welding slag is pretty light but if iron slag was used for ballast it must be substantial

Here in Seattle they do nothing. At this point I’d be happy if they filled them with chewing gum, crack pipes, and McDonald’s wrappers.

I’m annoyed they don’t include pictures of the iron fillings.

Show me the proof please.