This might be a stupid question. Does anyone have technical knowledge regarding the usage of dirty wrought in kitchen knives from a food safety standpoint? Would any potentially harmful chemicals (not sure if there is any to be concerned about) "leach" into the food?
Dirty Wrought
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What are you considering dirty wrought? Reused like telegraph wire etc? If so I have not noticed anything.
I actually have no idea if the wrought iron used is dirty to begin with or made dirt during knifemaking somehow. As far as the source metal goes, it seems to me anything can be used nowadays - from wine barrel hoop bands to old wagon wheels. Simon Maillet literally calls his wrought iron cladding knives "garbage knives".
aporigine
The slow blade penetrates the winter squash
Iron, carbon, perhaps sulfur and a bit of phosphorus. Toxicologically mellow.
https://en.wikipedia.org/wiki/Low-background_steel also a factor? Heh
It’s kind too low to affect any knives, more for sensitive equipments. But steel from salvaged ship is cool
OK is it possible they are referring to the process? I could be wrong but sometimes I believe they refer to a dirty wrought as iron having issues with adhering to the core during the forging and they do not always know how good or bad the forge weld was until they start grinding.
"Dirty" wrought iron is typically referring to iron with significant slag inclusions, which come from the original manufacturing process. People like using it for cladding b/c the slag doesn't alloy, and so leaves the cool banding patterns that some of us find attractive. Slag can include a lot of different crap in it, but from what I understand it will primarily be oxides and silicates of calcium, magnesium, silicon and aluminum. Most of these are not dangerous to humans upon ingestion, and definitely not at the levels that you might find migrating into food from the cladding of a knife (if there was any migration at all).
My wrought clad knife takes a more stable less reactive patina than my traditional clad iron knife.
Caveat: sample size of one each
Caveat: sample size of one each
Matt Jacobs
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I am no scientist but its hard to imagine any negative effects from "Dirty Wrought". I would think anything bad would be destroyed during the forge welding process. I did find an article about some slag that contained high levels of lead and arsenic but it doesnt look like that is the norm.
"Dirty wrought" is just a moniker for heavily etched wrought iron AFAIK. So the contrast from the natural slag inclusions is as visible as possible.
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I will fully throw my hands up and admit I’m wrong as I am sure you know better than me, but my understanding was always that the difference between ‘clean’ and ‘dirty’ wrought is that ‘clean’ wrought has been worked more to remove a higher proportion of impurities.
I'm not an authority on the subject by any means, though I've worked with wrought a few times. Wrought, as made, is pretty heterogenous stuff. By forging and folding, it homogenizes and gets cleaned, in much the same way bloomery steel (tamahagane) does. I don't know if the monikers of "clean" and "dirty" have any official significance, I just meant in my last post that "dirty" has more to do with the depth of the etch and the overall aesthetics than the inherent cleanliness of the material.
For a time there were blades being made of "shear steel". Essentially strips of wrought iron that had been carburized and forge welded together. "Double shear" had been folded once, "triple shear" twice. The more folds the more homogenous looking the steel. Making shear steel is one of my many round-to-it projects.
For a time there were blades being made of "shear steel". Essentially strips of wrought iron that had been carburized and forge welded together. "Double shear" had been folded once, "triple shear" twice. The more folds the more homogenous looking the steel. Making shear steel is one of my many round-to-it projects.
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Makes sense! Do you think it’s one of those definitions (like ‘workhorse’
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Darn, I was hoping this was a picture thread.
Most likely.Makes sense! Do you think it’s one of those definitions (like ‘workhorse’
![20230606_161932[1].jpg](https://cdn.imagearchive.com/kitchenknifeforums/data/attach/299/299067-20230606-161932-1-.jpg "20230606_161932[1].jpg")
The third from the left is iron clad and the far right is wrought.
SylvainM
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Hi guys,
Jumping in with my one penny input
As far as I use it, dirty wrought would refer to a wrought iron used as clad as it is. As previously mentioned the production process of those irons, also called Pudley iron, included a phase where it was rolled on itself basically. This created this cool "structure" that most visually like, but also included many defects along the path. If you take this same wrought and work it at the forge to fold it, it will reduce those defects and make the wrought "clean".
Visually the difference would be that you wouldn't find any "fracture" in the clean one that you may find in the dirty one, as you can observe on the picture below from one of my own production, slightly above the nickel line.
From a blade performance perspective there is no significant difference IMO. However it is true that such fractures at the surface of the cladding can be nice spots for rust and/or food to find a nest...
Jumping in with my one penny input
As far as I use it, dirty wrought would refer to a wrought iron used as clad as it is. As previously mentioned the production process of those irons, also called Pudley iron, included a phase where it was rolled on itself basically. This created this cool "structure" that most visually like, but also included many defects along the path. If you take this same wrought and work it at the forge to fold it, it will reduce those defects and make the wrought "clean".
Visually the difference would be that you wouldn't find any "fracture" in the clean one that you may find in the dirty one, as you can observe on the picture below from one of my own production, slightly above the nickel line.
From a blade performance perspective there is no significant difference IMO. However it is true that such fractures at the surface of the cladding can be nice spots for rust and/or food to find a nest...
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Hey,
I am not sure me or others started to classify some wrought iron clean or dirty, but I am doing that classification myself.
For my knives only, my classification is :
Clean : wrought iron with fiber structure (I think it is puddle iron but if there is expert there I'll be glad to learn more), meaning the iron looks like folded because of the process it was made with (still an industrial process starting with cast iron, decarbonisation, then wrought iron). But there is no trace of slag, no delamination, no dark lines. This iron is not folded by myself but found and use as it is.
Dirty : wrought iron with strong fiber structure (puddle iron too), the iron looks like folded but this fibering is coming from the puddle industrial process. There is little to a lot of slag (dark lines) in the composition, slag doesnt weld well to the iron, so there is often delaminations. Those one are sometimes very dirty and very fragile as soon as you stretch them too thin when forging, but some are less dirty (I select those to make my knives) and are solid enough to be forged thin without them to crack or crumble. Again, I don't fold that iron myself on my knives, it is found and use as it is.
Last category could be some very dirty iron I sometimes want to work though, but too fragile for me to make a knife as it is. I will then make a billet of different pieces of it and will fold them like 3 to 5 times to clean and refine it so it is clean enough to be worked the way I like. There still will be some slag left after that process but it will appear much smaller.
Bloom iron in my mind is not coming from industrial process that start with cast iron and remove carbon to get iron ; but comes from artisanal process with iron coming straight from iron oxide, iron ore. With this process, the metal did not reach the fusion temperature so did not become cast iron : it is made iron straight away.
Considering rust : all irons made of iron and carbon without enough chrome will rust, and even with chrome, iron wants to come back to it's original shape : the oxide, so even some stainless can rust. (there is almost no iron metal to be found on earth, most iron as metal is made by humans). For sure the more rough the surface is, the easier the rust will be difficult remove if is happening. Rust is happening not really with water in my experience (as I am sometimes working a blade with water whetstones for days) but from an acidic water. Work with a basic water, clean and dry your blade after use, you should have less rust appearing.
Final : rust is iron oxyde. Sure it doesn't look great. Sure if rust can find some small places to get stuck, other bacteries and maybe wrong ones can find a place too. But iron oxide, rust, is not something that will harm you strongly in most cases. Maybe I am french and I am a little too cool about that topic but iron oxide is not proved to be dangerous in small quantity. Tetani is dangerous, but is a bacteri, not iron oxide. More info here : https://www.prevention.com/food-nut...ing-rusty-cookware-really-that-big-of-a-deal/
But maybe there is more complete, serious writing about that topic.
I am not sure me or others started to classify some wrought iron clean or dirty, but I am doing that classification myself.
For my knives only, my classification is :
Clean : wrought iron with fiber structure (I think it is puddle iron but if there is expert there I'll be glad to learn more), meaning the iron looks like folded because of the process it was made with (still an industrial process starting with cast iron, decarbonisation, then wrought iron). But there is no trace of slag, no delamination, no dark lines. This iron is not folded by myself but found and use as it is.
Dirty : wrought iron with strong fiber structure (puddle iron too), the iron looks like folded but this fibering is coming from the puddle industrial process. There is little to a lot of slag (dark lines) in the composition, slag doesnt weld well to the iron, so there is often delaminations. Those one are sometimes very dirty and very fragile as soon as you stretch them too thin when forging, but some are less dirty (I select those to make my knives) and are solid enough to be forged thin without them to crack or crumble. Again, I don't fold that iron myself on my knives, it is found and use as it is.
Last category could be some very dirty iron I sometimes want to work though, but too fragile for me to make a knife as it is. I will then make a billet of different pieces of it and will fold them like 3 to 5 times to clean and refine it so it is clean enough to be worked the way I like. There still will be some slag left after that process but it will appear much smaller.
Bloom iron in my mind is not coming from industrial process that start with cast iron and remove carbon to get iron ; but comes from artisanal process with iron coming straight from iron oxide, iron ore. With this process, the metal did not reach the fusion temperature so did not become cast iron : it is made iron straight away.
Considering rust : all irons made of iron and carbon without enough chrome will rust, and even with chrome, iron wants to come back to it's original shape : the oxide, so even some stainless can rust. (there is almost no iron metal to be found on earth, most iron as metal is made by humans). For sure the more rough the surface is, the easier the rust will be difficult remove if is happening. Rust is happening not really with water in my experience (as I am sometimes working a blade with water whetstones for days) but from an acidic water. Work with a basic water, clean and dry your blade after use, you should have less rust appearing.
Final : rust is iron oxyde. Sure it doesn't look great. Sure if rust can find some small places to get stuck, other bacteries and maybe wrong ones can find a place too. But iron oxide, rust, is not something that will harm you strongly in most cases. Maybe I am french and I am a little too cool about that topic but iron oxide is not proved to be dangerous in small quantity. Tetani is dangerous, but is a bacteri, not iron oxide. More info here : https://www.prevention.com/food-nut...ing-rusty-cookware-really-that-big-of-a-deal/
But maybe there is more complete, serious writing about that topic.
SylvainM
KKF Supporting Craftsman
Thanks for the clarification @milangravier , once again sharing your knowledge and teaching us all a lot 
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Somebody please find some truly dirty wrought iron from Chernobyl and forge it so KKF can find out
aporigine
The slow blade penetrates the winter squash
“that’s not swarf. It’s fallout”
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I bet it glows betters than copper linings
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The slow blade penetrates the winter squash
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HolyDiverScallop
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aporigine
The slow blade penetrates the winter squash
yanagiboommmmmmm
