smelting Should we be able to cast iron?

[programmer-S12]

I mean, cast iron is pretty iconic, and coke is in the game, so I feel like we should be able to cast iron in a crucible, possibly even for slightly higher stats than normal iron.

https://en.wikipedia.org/wiki/Cast_iron

I haven't got iron in my game yet, and I'm not sure if there's a reason this hasn't been added, but I thought I'd suggest it.

Maybe it would be a bit much to add blast furnaces, but perhaps it should be possible to use a crucible in a fire pit to smelt iron if you use coke.

[LadyWYT]

51 minutes ago, programmer-S12 said:

Maybe it would be a bit much to add blast furnaces

Pretty sure that blast furnaces are on the devs' to-do list. To answer the question otherwise, I do think it makes sense to allow iron/steel casting as part of the late game tech tree. It could be locked behind tier 3 refractory bricks if it really needs a gate, so that the player has to have made steel first and can't just set everything up with basic bronze and iron.

[programmer-S12]

On 10/12/2026 at 5:00 PM, LadyWYT said:

so that the player has to have made steel first and can't just set everything up with basic bronze and iron.

Why does steel need to be first? So long as steel is significantly more powerful, cast iron could be a nice intermediate material. The player would still need to make coke first, which requires bricks.

Edited October 16 by programmer-S12
Fixed grammar

[MKMoose]

1 hour ago, programmer-S12 said:

[...] perhaps it should be possible to use a crucible in a fire pit to smelt iron if you use coke.

A regular crucible, even with coke, isn't sufficient to reliably smelt iron - that's related to why bloomeries were such an important historical milestone.

You could potentially melt scrap iron, but that will usually require a better crucible and a furnace, not a clay crucible and a firepit as far as I can find.

It would be entirely plausible and historically accurate make crucible steel in a crucible, which relies on diffusion more than melting if I recall correctly.

As for cast iron, my thought is that a proper blast furnace really should be the way to go. Development of the blast furnace (as well as the finery forge process closely related to it) is among the most important technological advancements of the Renaissance, so I don't see much reason to shy away from it and continue making iron in simple bloomeries while we already have roughly 17th-century cementation furnaces for steelmaking. It would certainly be a complex feature, but I don't feel like that should be a justification to avoid it - just a reason to put in extra effort to keep the process reasonably streamlined and intuitive.

 

1 hour ago, programmer-S12 said:

[...] cast iron in a crucible, possibly even for slightly higher stats than normal iron.

Cast iron is brittle. It has a number of advantages which make it comparable or better than wrought iron for some applications (e.g. scythe, cooking pot, stove, some intricate shapes), but as a general rule it is strongly suboptimal for anything which takes impact (e.g. chisel, hammer, pickaxe, any weapons or armor). Simplifying the comparison to better-worse isn't really productive in this case, much less so than for most other metals.

 

26 minutes ago, LadyWYT said:

It could be locked behind tier 3 refractory bricks if it really needs a gate, so that the player has to have made steel first and can't just set everything up with basic bronze and iron.

Do keep in mind that real blast furnaces were first built several centuries before cementation furnaces. And that's considering Europe, but it was much earlier still in China.

 

54 minutes ago, LadyWYT said:

Pretty sure that blast furnaces are on the devs' to-do list.

I don't think I've ever seen any mention of this other than a fairly simplistic WIP implementation from many years ago.

Regardless, if they are not on the devs' to-do list, then I certainly hope they make their way onto it.

[LadyWYT]

48 minutes ago, programmer-S12 said:

Why does steel need to be first? So long as steel is significantly more powerful, cast iron could be a nice intermediate material. The player would still need to make coke first, which require bricks.

47 minutes ago, MKMoose said:

Do keep in mind that real blast furnaces were first built several centuries before cementation furnaces. And that's considering Europe, but it was much earlier still in China.

I'm thinking of iron processing in general, not adding a new type of iron. To me the general goal of casting iron/steel is that the materials become much easier to work in large quantities; ie, instead of working individual iron blooms or turning individual ingots into various things, the player can sink the resources into a large refinery structure and thus make refining and forging those materials faster and easier. Hence why I say that such a setup can potentially be gated behind steel, if necessary--it's to push the player through the more rudimentary processes first before they get the convenience, rather than the player sticking to bronze/only bothering with the most basic of iron and rushing the setup.

54 minutes ago, programmer-S12 said:

So long as steel is significantly more powerful, cast iron could be a nice intermediate material

Regarding this specifically, cast iron as an intermediate material isn't particularly useful, since meteoric iron already fills that niche with much less effort involved.

 

[Rainbow Fresh]

Leaving the discussion for iron and steel variants/alloys as additional metallurgy content aside for another discussion, I'm all for a processing tier after the cementation furnace; something that allows us to produce iron or steel in bulk without all the painstaking intermediary steps. If it requires having made some steel first in said cementation furnace to build, makes sense. If it requires tier 3 refractory bricks, makes sense. Hell, even if it is technically more expensive to run than the bloomery + smithing or cementation furnace + smithing equivalent, so be it; the ability to just feed the beast and then pour 10 ready-to-use ingots is worth it.

[MKMoose]

17 hours ago, programmer-S12 said:

Maybe it would be a bit much to add blast furnaces, but perhaps it should be possible to use a crucible in a fire pit to smelt iron if you use coke.

Wootz steel (a type of crucible steel first made in the 1st milenium BC in Southern India) is very noteworthy here, because it does technically allow iron smelting (but not straight-up melting) into a very high quality steel in relatively small batches. Interestingly enough, the wootz process was almost entirely unknown in Europe until the 17th century, but it didn't catch on once it was introduced in spite of its high quality due to industrial-scale shear steel production being already established in Europe by that point.

I'm not certain that it necessarily makes sense to introduce it to the game, because realistically it would effectively be an endgame steel unlocked in the Bronze Age, but it is very interesting nonetheless.

 

1 hour ago, Rainbow Fresh said:

Leaving the discussion for iron and steel variants/alloys as additional metallurgy content aside for another discussion, I'm all for a processing tier after the cementation furnace; something that allows us to produce iron or steel in bulk without all the painstaking intermediary steps.

I do generally tend to agree, but I'm not sure why it should be after the cementation furnace. Note that, realistically, the chronology of iron and steel production in Europe can generally be simplified to the following (other regions complicate it a bit):

• Bloomery - onset of the Iron Age, c. 1200 BC - simple iron production through blooms. Steel can be made in small quantities by cutting off high-quality parts off of blooms. Can be improved with bellows.
• Some significant intermediate designs start popping up around the 10th century.
• Blast furnace - ~12th century in Europe - a nearly direct successor to the bloomery, which allows to produce (1) cast iron and (2) higher quality iron and steel through the finery forge process, more quickly and and more efficiently than ever before. Since its introduction, it has been continuously improved and upscaled, though the fundamental working principle remains the same.
• Cementation furnace - ~16th century - more of a post-p and its primary benefit is higher quality shear steel, though it's slow and inefficient. It typically relied on higher-quality wrought iron production from blast furnaces to supply the steel production.
• The next major categorical changes would only come in the 18th century with the crucible furnace and puddling furnace.

For the game's purposes, though some inaccuracies and simplifications are naturally permissible, I think it would be quite odd to add something after the cementation furnace. If not introduce a blast furnace as a fixed middle step to make cementation the expensive end goal, then making them independent of each other wouldn't seem unreasonable - this would allow the player to choose whether they want to prioritize cast iron and more efficient wrought iron production, or more directly go for higher-quality steel.

12 hours ago, LadyWYT said:

I'm thinking of iron processing in general, not adding a new type of iron. To me the general goal of casting iron/steel is that the materials become much easier to work in large quantities; ie, instead of working individual iron blooms or turning individual ingots into various things, the player can sink the resources into a large refinery structure and thus make refining and forging those materials faster and easier. Hence why I say that such a setup can potentially be gated behind steel, if necessary--it's to push the player through the more rudimentary processes first before they get the convenience, rather than the player sticking to bronze/only bothering with the most basic of iron and rushing the setup.

Fair. Besides the above note on why for historical reasons I don't think just adding a step after the cementation furnace is a good idea, I would absolutely be in favor of the addition of a blast furnace for high-volume ironmaking.

I would argue that making it a parallel unlock with the cementation furnace could even be the better choice, as it would open up player freedom instead of kind of just lengthening a fixed progression line. A blast furnace could primarily improve efficiency and speed of processing as well as unlock a few things like a cast iron stove, whereas a cementation furnace could be the preferred choice for high-quality but expensive tools, weapons and armor - ultimately both would be necessary to get the full combined benefits either way.

 

 

12 hours ago, LadyWYT said:

Regarding this specifically, cast iron as an intermediate material isn't particularly useful, since meteoric iron already fills that niche with much less effort involved.

I might have told you this already so apologies if I'm repeating it, but learning about real-life meteoritic iron has made it very difficult for me to take the in-game implementation seriously. Jewellry and other religious or cultural items. Sometimes small tools, but primarily in Greenland where the Cape York meteorite provided relatively easy access to meteoritic iron, in contrast with most regions of the world where its status was often similar to precious metals and gemstones. Meteoritic iron can't be smelted because it's already metallic, so it was mostly cold-worked into a desired shape, sometimes hot-worked - which is technologically less sophisticated than copper casting. And it's unsuitable for large-scale processing because meteorite composition is very inconsistent.

On cast iron, instead of discussing where it would fall between the main progression metals, I think it would make more sense to make it most useful outside of toolmaking - primarily used for things like cookware and mechanical components. For tools, it is realistically only useful for a narrow selection of them, especially agricultural tools, which could actually be a nice way to reduce maintenance costs of farming or broadly homesteading in the mid to late game, and it would also contrast with steel which is particularly suited to more progression-critical tools as well as weapons and armor.

[Rainbow Fresh]

2 minutes ago, MKMoose said:

[...] but I'm not sure why it should be after the cementation furnace.

Because unless we dive into steel alloys or something to give the cementation furnace an edge - it becomes immediately obsolete to the point where there is no reason reason to ever make one. Gameplay-wise the progression right now is to make iron ingots from iron blooms in a bloomery - batch size of 6, needs post-processing. Steel in the cementation furnace, batch size of 16, requires pre-processing, post-processing and a shitton of time. If we now add means to cast iron/steel akin to a crucible (+- pre-processing of resources), you can easily mass produce iron and steel without having to deal with the post-processing. If that is available before the cementation furnace, why would you downgrade to one, ever?

[MKMoose]

1 hour ago, Rainbow Fresh said:

Because unless we dive into steel alloys or something to give the cementation furnace an edge - it becomes immediately obsolete to the point where there is no reason reason to ever make one. Gameplay-wise the progression right now is to make iron ingots from iron blooms in a bloomery - batch size of 6, needs post-processing. Steel in the cementation furnace, batch size of 16, requires pre-processing, post-processing and a shitton of time. If we now add means to cast iron/steel akin to a crucible (+- pre-processing of resources), you can easily mass produce iron and steel without having to deal with the post-processing. If that is available before the cementation furnace, why would you downgrade to one, ever?

There's a couple points here.

• To make wrought iron or steel using a blast furnace, you first cast pig iron (a pig is a large ingot-like piece cast from the blast furnace), then you hammer the impurities and excess carbon out of it (that's the finery forge process). Besides cast iron, which is a careful cast directly into a desired shape, it's not possible make ready-to-use iron or steel with the blast furnace (even cast iron should realistically be touched up after casting, but that can be abstracted away with no issues).
• Steel from the cementation furnace realistically requires incomparably more work than just "shave off a few impurities off the blister steel". It is referred to as shear steel, because its production involves shearing blister steel rods and welding them back together, repeated several times.
• Steel from the cementation furnace realistically is of signficantly higher quality than earlier types of steel - that's why it was useful in spite of the process being slow and inefficient.
• Cast iron is a practically separate product of the blast furnace.
• Cast steel essentially didn't exist until much later.
• Crucible steel is a separate topic.

You can just make it work, it's greatly simplified in the game anyways.

• It would be quite reasonable to make it only possible to produce regular wrought iron (via pig iron) and cast iron with the blast furnace, keeping steel restricted to the cementation furnace - that's what I was alluding to when saying that the blast furnace and cementation furnace could be independent features that the player could build in either order.
• Alternatively, shear steel from the cementation process could be better than regular steel. Kind of like you've said yourself, though with no need for any alloys. The cementation process and subsequent processing could be made more advanced and expensive as well if there's need to make more space in progression for the blast furnace.

Edited October 13 by MKMoose

[programmer-S12]

On 10/12/2026 at 6:43 PM, MKMoose said:

Cast iron is brittle. It has a number of advantages which make it comparable or better than wrought iron for some applications (e.g. scythe, cooking pot, stove, some intricate shapes), but as a general rule it is strongly suboptimal for anything which takes impact (e.g. chisel, hammer, pickaxe, any weapons or armor). Simplifying the comparison to better-worse isn't really productive in this case, much less so than for most other metals.

Ah. I see. My prior understanding was that Abraham Darby's invention was coke and thus cast iron, and that allowed iron to be less brittle. My apologies. I suppose if casting iron from a crucible using coke is implemented as a "stand in" for blast furnaces, it should just produce normal iron.

On 10/12/2026 at 7:37 PM, LadyWYT said:

Hence why I say that such a setup can potentially be gated behind steel, if necessary--it's to push the player through the more rudimentary processes first before they get the convenience, rather than the player sticking to bronze/only bothering with the most basic of iron and rushing the setup.

Interesting take. In my own world, I now have iron, but I don't coke or steel yet, so I assume you know what you're talking about. I wonder how that would work though... Maybe teir 1, 2, and 3 "refractory crucibles"?

On 10/13/2026 at 9:58 AM, MKMoose said:

On cast iron, instead of discussing where it would fall between the main progression metals, I think it would make more sense to make it most useful outside of toolmaking - primarily used for things like cookware and mechanical components. For tools, it is realistically only useful for a narrow selection of them, especially agricultural tools, which could actually be a nice way to reduce maintenance costs of farming or broadly homesteading in the mid to late game, and it would also contrast with steel which is particularly suited to more progression-critical tools as well as weapons and armor.

The historical discussion is very cool, but for gameplay purposes, I was thinking that casting iron from a crucible would be a good "stand in" for blast furnaces, but being able to use iron to make cooking pots that heat up quicker and make more portions at once, or crocks that could perhaps store more, or possibly have better preservation, would be a great addition to go alongside blast furnaces if they do get added.

[Mac Mcleod]

On 10/12/2026 at 10:06 AM, programmer-S12 said:

I mean, cast iron is pretty iconic, and coke is in the game, so I feel like we should be able to cast iron in a crucible, possibly even for slightly higher stats than normal iron.

https://en.wikipedia.org/wiki/Cast_iron

I haven't got iron in my game yet, and I'm not sure if there's a reason this hasn't been added, but I thought I'd suggest it.

Maybe it would be a bit much to add blast furnaces, but perhaps it should be possible to use a crucible in a fire pit to smelt iron if you use coke.

Humans were casting iron centuries before they could produce steel in large quantities, and steel was not required to make cast iron. The key was achieving a high enough furnace temperature to melt iron with sufficient carbon in it.
 

Cast iron typically melts at about 1,150–1,200°C (2,100–2,190°F), depending on its carbon content and other alloying elements.   So you could use charcoal, black coal, or anthracite.   It can be cast into clay, sand, or iron molds (China).

Cast iron cannot be used for nails, scissors, tongs, weapons, or armor.   It's too brittle.

For comparison:

Pure iron: 1,538°C (2,800°F)
Cast iron: roughly 1,150–1,200°C
Wrought iron: 900–1,250°C
Steel: typically around 1,370–1,510°C, depending on composition
 

[River Oak]

cast iron fences and lamp posts, my beloafed, the true end game decoration items 

[programmer-S12]

9 hours ago, Mac Mcleod said:

Cast iron cannot be used for nails, scissors, tongs, weapons, or armor.   It's too brittle.

Then maybe cast iron from crucibles in Vintage Story would be a different type of "cast iron"? It turns out there are multiple...

5 hours ago, River Oak said:

cast iron fences and lamp posts, my beloafed, the true end game decoration items 

Yeah, and that could be for later once blast furnaces are added. I'm thinking of being able to use clay moulds for iron, and being able to have iron lamellar; with crucibles being used as a "stand-in".

[Teh Pizza Lady]

Blast furnaces shouldn't require tier 3 bricks since I don't think many of us have even created tier 3 bricks. They require Titanium which is a rare item in the game to begin with, and the metal, while it did see use in blast furnaces, was not a requirement which I will explain below.

Historically, blast furnaces were often rebuilt frequently since the refractory lining deteriorated quickly. Rebuilding this was called relining the furnace. A typical furnace could last upwards of 10 years before needing to be relined and modern ones can run even longer. What usually wore out the fastest was the hearth. The bottom of a furnace holds the molten iron and slag at around 1500 celcius and the carbon lining there tends to erode away. Sometimes titanium is added to the charge as the furnace is running in because it forms a protective layer that it will extend the life of the hearth.

Parts that get replaced often:

• Tuyeres - replaced every couple of months
• Cooling plates - Copper or cast iron plates in the walls designed to absorb and radiate heat away from the steel casing
• Tap holes and casting clay - replaced with every cast just about
• Bell - charging system at the top of the furnace which saw constant wear and tended to bear a lot of weight under high heat as charges were added to the furnace.

The steel shell also sometimes needed repair.

Early blast furnaces had stone/clay linings that only lasted a couple of years and their operation was seasonal with relining just being a routine part of operating one. I imagine that's the type of blast furnaces we'll get in the game, but if you want to make steel required, then there is historical evidence to support its use since the outer shell of the furnace was often made of steel. However for simplicity sake, the furnaces we'll probably end up getting will be period-appropriate and not have steel casings and will be an earlier type of furnace (English Weald or the German type) that typically lasted only a few months before needing to be repaired.

Edited October 17 by Teh Pizza Lady

[Chuckerton]

Theres actually some kind of casting furnace in one of the procedural dungeons

I dont know what ore that is, theres a pile of "impure ore" or something along those lines at the top so it could probably be anything. It looks like its either copper or heavily rusted iron. Point is, larger scale metal production is not unprecedented in this game and i hope we get to make stuff like this. 

If you were worried about game balance/progression, i would say theres a number of things they could do, but theres one solution that i can think of that i feel is fair. 

Requiring steel nails for a blast furnace. The blast furnace can bulk cast only up to iron. Bulk metal production is now a steel-tier production option that takes over the crucible/bloomeries. I dont like the idea of making it require high tier refractory bricks, this game has enough of "scour the map looking for this absurdly rare deposit" (looking at you halite). By the time youre making steel, getting fire clay bricks for bloomeries is more of a chore than a challenge. I would rather run a blast furnace and get enough iron for a few batches of steel and have to patch up my blast furnace. 

[Dilan Rona]

from a historical point of view, bronze can be cast. Iron however cannot, as it requires forging on an anvil to make the ingots (yes ingot molds do exist, I am aware of it), and also any tools and weapons. Granted the forging process could do with some work regarding rotation. Otherwise I am happy with it so far, and even found a way to cool down iron tools and weapons without it shattering on me 60% of the time (like it did in the past to me).

[Mac Mcleod]

On 10/19/2026 at 4:10 AM, Dilan Rona said:

from a historical point of view, bronze can be cast. Iron however cannot, as it requires forging on an anvil to make the ingots (yes ingot molds do exist, I am aware of it), and also any tools and weapons. Granted the forging process could do with some work regarding rotation. Otherwise I am happy with it so far, and even found a way to cool down iron tools and weapons without it shattering on me 60% of the time (like it did in the past to me).

Cast iron originated in China around the 5th century BCE with charcoal, where furnaces reached temperatures sufficient to melt iron. It spread gradually to Europe, where it became important during the Industrial Revolution. It wasn't until the 18th century, that Abraham Darby pioneered the use of coke instead of charcoal for smelting, enabling larger-scale production. Cast iron became widely used for cookware, machinery, pipes, bridges, and building components. Its strength under compression and excellent castability made it an essential industrial material.    

However, it is brittle when struck.   It's not suitable for weapons, armor, etc.

The main difference between cast iron, steel, and wrought iron is the amount of carbon mixed with the iron.   

[MKMoose]

On 10/16/2026 at 10:26 PM, programmer-S12 said:

My prior understanding was that Abraham Darby's invention was coke and thus cast iron, and that allowed iron to be less brittle. My apologies. I suppose if casting iron from a crucible using coke is implemented as a "stand in" for blast furnaces, it should just produce normal iron.

Abraham Darby did indeed introduce a new method for producing cast iron with coke-fired furnaces, which allowed to produce thinner and cheaper pots, although cast iron in general was introduced much earlier than that, especially in China (see e.g. cast iron history, or more generally ferrous metallurgy). His cast iron was likely less brittle than that made with earlier methods, but cast iron as a whole is regardless generally brittle relative to wrought (forged) iron and to steel.

 

On 10/17/2026 at 7:39 PM, Teh Pizza Lady said:

Blast furnaces shouldn't require tier 3 bricks since I don't think many of us have even created tier 3 bricks. They require Titanium which is a rare item in the game to begin with, and the metal, while it did see use in blast furnaces, was not a requirement which I will explain below.

[...] Sometimes titanium is added to the charge as the furnace is running in because it forms a protective layer that it will extend the life of the hearth.

This is a fairly modern use of titanium. For refractory bricks specifically as it's used in the game, ilmenite is as far as I can tell not useful at all due to its relatively low melting point of ~1400 °C - proper refractory materials tend to favor melting points of at minimum ~1600 °C, and some go above 2000 °C. I have no idea why ilmenite is used as a refractory in the game, but it should have no effect on whether high-tier refractory bricks should be required for the blast furnace because it's not a direct use of titanium.

 

On 10/17/2026 at 7:39 PM, Teh Pizza Lady said:

Cooling plates - Copper or cast iron plates in the walls designed to absorb and radiate heat away from the steel casing

You're speaking about fairly modern furnaces in general. Specifically metal reinforcements and cooling systems seem to only appear in the late 19th century as far as I can find, so it is entirely irrelevant for the game's purposes. For simplicity's sake we can pretty much even skip the lining and just use refractory bricks for the whole main furnace structure and stone for the hearth, to stay close to the game's existing mechanics and style.

 

On 10/18/2026 at 6:13 PM, Chuckerton said:

The tall furnace on the right is explicitly named a blast furnace in game files. The one next to it is almost certainly a reverberatory furnace which may be used for a number of metals including copper and copper alloys, tin, lead and pig iron starting from the 17th century and in this case has solidified iron in the hearth. From the late 18th century it has also been used for processing pig iron into wrought iron in a process referred to as puddling.

 

On 10/18/2026 at 6:13 PM, Chuckerton said:

If you were worried about game balance/progression, i would say theres a number of things they could do, but theres one solution that i can think of that i feel is fair. 

Requiring steel nails for a blast furnace.

I don't quite see where those nails would be useful. Frankly, I feel like the best way to restrict the blast furnace in progression is just through setup costs and infrastructure. It would be a bit strange, even for a significantly simplified process, not to require:

• the main blast furnace structure, probably made from any refractory bricks (realistically you don't even need fire clay, but I guess it's fine for game purposes) which requires a pulverizer,
• large bellows, which means a lot of leather, almost certainly mechanically powered and ideally powered with a water wheel to ensure continuous air blast,
• specialized casting molds for some items including cookware (potentially with a special ladle or something of the sort to pour the iron in a more controlled way), and a rough casting bed for pig iron,
• ideally a separate finery hearth with its own bellows for remelting pig iron to make it into wrought iron.

A lot of simplifications are naturally possible, but in general I feel like just the complexity and setup cost of the whole process seem like they are enough of a progression gate that we really don't need any additional restrictions on top, be it steel or high-tier refractory bricks.

The greatest easily justifiable hard restriction is iron, I think, since it would probably be preferable not to allow the player to skip bloomeries entirely, but there's no real way to use it for the furnace itself that I can find - maybe for the tuyeres and bellows, which would still be a pretty arbitrary restriction but probably much more defensible.

 

Frankly, as I'm looking into it more, I'm getting the impression that it is ultimately a pretty obscure topic. Making the mechanics fully realistic and historically accurate would naturally be impractical (if you can even find properly reliable sources to base some of the smaller details on), but trying to simplify it for better approachability while retaining historical accuracy can also be a fool's errand.

• Historically, a blast furnace can only be used to smelt iron, because that's what it is specifically designed to do.
• A proper blast furnace needs to run continuously with no breaks - simplifying this is entirely possible and likely preferable, but then that would be more like an 11-12th century intermediate furnace.
• A blast furnace naturally needs a lot of setup work as mentioned earlier.
• It can be tricky to make the blast furnace actually worthwhile for mass production of iron unless greatly simplified, since the process has a significant extra step relative to the bloomery process:
  • smelt iron and cast into pig iron,
  • remelt pig iron in the finery hearth to burn out the excess carbon and let it form a bloom,
  • hammer out the impurities out of the bloom to make wrought iron.
• Making the blast furnace require additional maintenance would make it further difficult to let it naturally outcompete the bloomery. I've had the thought to make it only take damage when operated improperly, to make the mechanic more interesting and allow the player to reduce costs with some skill or care.

Edited Wednesday at 11:44 AM by MKMoose

[Mac Mcleod]

Okay, so the images won't post inline.  sorry about that.  I have links to them that I tested.

FYI:

The earliest Chinese ironmaking dates to roughly the 6th century BCE, while European blast furnaces appeared around the 12th–13th centuries CE.

For scale, some traditional Chinese blast furnaces were tiny, producing just 40–50 jin (roughly 44–55 pounds) of pig iron per day. Larger early Chinese furnaces could produce hundreds or more pounds daily.

Also FYI

Assuming the VS ingots are a solid rectangular block measuring 2 × 12 × 4 inches, an iron ingot (at 0.283 lb/inch^3) would weigh about 27 pounds.

In europe, 

Early blast furnaces generally cast molten iron into individual pieces called pigs, using channels formed in a sand bed. The pieces varied in size, but later historical examples give us a useful guide.

 

 

 

 

Typical pig iron

Around 3 feet long, 4–6 inches wide, and 3–4 inches thick. Some historical examples weighed roughly 50–125 pounds (23–57 kg).

https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2Ftse1.mm.bing.net%2Fth%2Fid%2FOIP.47A9wl0Y1a1_NHvs6VxomQHaEn%3Fpid%3DApi&f=1&ipt=df4d1ff23befea508e2851f4da7cf4f191ba15666f3d9bc1bccbac203696020c&ipo=images

 

The Sow

The larger main channel that fed the smaller pig molds also solidified into iron. It could be broken apart afterward; surviving examples include pieces around 16–24 inches long.

https://emuseum.colonialwilliamsburg.org/internal/media/dispatcher/198254/preview

Cool gold inlaid iron pig from  I found while digging around!
"The Han dynasty lasted from 206 BCE to 220 CE, with a brief interruption from 9 to 23 CE.

The artwork you linked, A Chinese Gold-Inlaid Iron Figure of a Sow, is attributed to that period, so it is approximately 1,800–2,200 years old. The auction listing does not give a more precise date for the object."

https://zacke.blob.core.windows.net/stock/20667-18-medium.jpg?v=63845169964213

 

Final FYI:

• Blast-furnace iron (pig iron): Typically contains about 3–4.5% carbon. It melts readily, flows into molds, but is generally too brittle to forge directly into useful tools.

• Wrought iron: Contains very little carbon, usually below 0.1%. It is relatively soft, malleable, and can be hammered into shape.

• Steel: Contains less carbon than pig iron, typically around 0.02–2.1%. Its properties depend on carbon content and heat treatment, making it useful for tools, springs, and weapons.

Edited Thursday at 05:27 PM by Mac Mcleod
final fixing image links

[Teh Pizza Lady]

On 10/21/2026 at 6:41 AM, MKMoose said:

You're speaking about fairly modern furnaces in general. Specifically metal reinforcements and cooling systems seem to only appear in the late 19th century as far as I can find, so it is entirely irrelevant for the game's purposes. For simplicity's sake we can pretty much even skip the lining and just use refractory bricks for the whole main furnace structure and stone for the hearth, to stay close to the game's existing mechanics and style.

If you had read the rest of the post, you would have seen where I conceded that it wasn't period-appropriate.  

On 10/17/2026 at 12:39 PM, Teh Pizza Lady said:

However for simplicity sake, the furnaces we'll probably end up getting will be period-appropriate and not have steel casings and will be an earlier type of furnace (English Weald or the German type) that typically lasted only a few months before needing to be repaired.

This is what I was referring to. Period-appropriate blast furnaces for Vintage Story will not have casings and will more than likely be the English Weald or German type... of which the name is escaping me atm. Anyway, reading before posting is important because you might end up restating something that someone else already said, especially if you're stating it to correct them and they already said it in their post. 

[MKMoose]

On 10/17/2026 at 7:39 PM, Teh Pizza Lady said:

[...] if you want to make steel required, then there is historical evidence to support its use since the outer shell of the furnace was often made of steel.

This statement clearly suggests that using steel casings could be considered for the game even if it's not the most preferable option. The word "often" implies that it would be historically common, but it doesn't convey the fact that the transition to steel shells only occured in the second half of the 19th century and as such is virtually irrelevant to the vanilla game from a historical perspective.

On 10/17/2026 at 7:39 PM, Teh Pizza Lady said:

However for simplicity sake, the furnaces we'll probably end up getting will be period-appropriate and not have steel casings and will be an earlier type of furnace (English Weald or the German type) that typically lasted only a few months before needing to be repaired.

7 hours ago, Teh Pizza Lady said:

Period-appropriate blast furnaces for Vintage Story will not have casings [...]

You only stress that early blast furnaces wouldn't have a steel casing (and an earlier sentence mentions that they had stone/clay lining), but fail to explicitly mention any other differences from the modern blast furnace that you've otherwise described.

• The first use of a proper charging bell seems to come from 1850. Granted, some early experiments may have been occurring earlier, but the proper bell-and-hopper system only comes into the picture in the middle 19th century.
• The first mention of "cooling metal plates", whatever that is exactly supposed to mean, seems to date to around the 1880s in the context of water cooling systems, which makes it doubly impractical for the game's limitations.
• Carbon lining was reportedly first used in the 1930s in Germany, and saw more widespread adoption after WW2 - while you did mention that early blast furnaces had stone or clay lining, your earlier phrasing could be easily seen as implying that carbon lining was a typical for blast furnaces potentially much earlier than the 20th century.
• The intentional use of titanium in blast furnaces was apparently only introduced in the late 20th century.

When you mention at least five modern blast furnace innovations from the 19th and 20th century without noting the timeframe when they were introduced or at least noting that they are modern, and only state two of them as missing from early furnaces, then that doesn't give me any confidence to assume that you actually know what those early blast furnaces ought to look like. A reader who doesn't necessarily have the time and inclination to extensively fact-check everything wouldn't get an accurate idea from your post either.

 

The blast furnace in the refinery actually has a closed top, which could suggest experiments from the 18th century or so, and that is alongside the reverberatory furnace which seems to come from the late 17th century at the earliest. Keep in mind that Tyron has said (here in an interview with Mahjong Blonsky) that the current plan is for the main technological progression line to stop at the Newcomen atmospheric engine, which was designed in 1712 - still well over a century before the primary modern design innovations in blast furnaces.

Even if we were to mostly ignore the historical concerns, I wouldn't personally expect any of the more modern furnace features except maybe a top hopper or hatch to make it into the game for the simple reason that they could make the furnace much more complex for little practical benefit - I would rather put most of the budget into making the fundamental process more engaging. Keep in mind, also, that 19th century blast furnaces could reach around 20 m or more in height and output counted in tons per day.

 

Personally, I would start from looking into simple European furnaces from roughly the 12-13th century, perhaps intermediate designs and not really blast furnaces in certain cases.

• Main structure made of refractory bricks with a 3x3 footprint and ~5 blocks of total height.
• Hearth at the bottom probably carved from stone.
• One or more special refractory brick blocks for the main iron tap, for slag, and for tuyeres.
• Additional infrastructure includes primarily:
  • bellows - possibly alternating paired piston bellows, though a lot of options are plausible,
  • a casting bed for pig iron - it could potentially be made of a variety of different materials, but the most notable option seems to be sand,
  • likely a slag pit - just a hole in the ground to prevent it from spreading out, no special implementation required,
  • likely a separate finery hearth for refining pig iron.
• Regarding details of operating the furnace:
  • A single cast could probably be made every ~8 in-game hours or so, and produce up to ~16 ingots worth of iron.
  • At five blocks of height, there would be space for three blocks of charge in the furnace.
  • The furnace could be allowed to operate in a process consisting of startup, an arbitrary number of batches, and shutdown, to better accomodate multiplayer servers by allowing convenient single casts.
    • Startup and shutdown would just mean adding fuel with no iron - this additional cost would produce a preference for continuous operation.
    • Alternatively, a perhaps even simpler implementation could involve reduced amount of fuel required to add to the charge while the furnace is partially full, to represent the partial reduction in higher parts of the furnace and incentivize more regular maintenance.
  • Damaging the bricks may only occur when the furnace is operated improperly (e.g. no fuel is added for proper shutdown).
  • If the furnace gets damaged during runtime then it would presumably need to be designed in a way that doesn't cause the furnace to just die arbitrarily at random points.
  • If at any point the furnace cools while there is still iron in it (primarily when the air blast stops, which is why water power would be very valuable), the remaining charge could solidify into a salamander, which could be mined out - it could be useless, or it could potentially be chiseled down to recover materials.
  • Slag produced as a byproduct could potentially be used for some building applications and as a P fertilizer.
• Regarding iron processing:
  • The default output of the blast furnace is pig iron.
  • Casting cooking pots and other cast iron items would ideally need a more controlled process, which would also save the implementation effort related to making all the molds integrate with the casting bed.
    • Direct casting is possible, but would be more implementation-heavy and inconvenient in practice because it doesn't allow mass production of raw material and gradual processing as it's needed.
    • I would strongly consider requiring to remelt pig iron in a crucible to make cast iron, and using individual molds in this way at much less implementation cost - it's not really historically accurate, but it's easy to implement and convenient in gameplay.
    • Some furnaces, including a reverberatory furnace given that it is present in-game in the refinery, could be also considered for this purpose, though that's a largely separate proposition and it shouldn't be the only way to produce cast iron products.
  • Processing pig iron into wrought iron would ideally require a separate finery hearth to cook out the excess carbon and let it form a bloom which would then be hammered. The hearth could probably just be a single new block roughly similar to a forge. Simplifying it and allowing to directly work pig iron wouldn't be entirely unreasonable, especially to make it more competitive with bloomery iron, but I would be very interested to see the full process reflected accurately regardless.

Edited yesterday at 11:33 AM by MKMoose