7 Things About Fairies and Iron

"‘Gold is for the mistress — silver for the maid —

Copper for the craftsman cunning at his trade.’

‘Good!’ said the Baron, sitting in his hall,

‘But Iron — Cold Iron — is master of them all.’"

- Kipling, 'Cold Iron'

Folklore about the Othercrowd stretches back centuries, with much of the recorded material we have focusing on protection against them. This is logical as they were thought to be able to harm humans as well as steal humans away. One of the main items recommended for protection against fairies is iron, although in the modern world I see a great deal of confusion on the subject and related topics. I thought it might be helpful to have a discussion here about iron, its uses, and some of the beliefs around it, so to that end I'm offering 7 points on fairies and iron:

1. Apotropaic Iron

Iron is said in folklore to protect against a wide range of spirits and negative magics including many of the Good Neighbors and Alfar, Ghosts, Demons, and witches. Iron objects deter the majority of the Other Crowd who are averse to its presence and things like knives, scissors, nails, and horseshoes were recommended as protective objects. It is said that cemeteries had iron fences to contain any ghosts inside. Similarly older folklore said that demons were also repelled by iron, and it was believed to break the magic of witches. A horseshoe hung up above a doorway kept out a wide range of spirits as well as protecting from baneful magic.
There is no set understanding of why iron works for this, but the belief is very widespread. 

2. Fairies and Iron

Across Western European folklore, particularly in the Celtic language speaking cultures and the Germanic cultures, we find the idea that iron is an ideal protection against Otherworldly beings. There is no agreement whether this must be blacksmith forged iron or any form of iron, but as mass production has come in since the industrial revolution there seems to be no indication that iron in any form is less effective. In fact we do have British accounts claiming that railways and trains drove off the Good People as they came into new areas, something that is also attributed to iron church bells; while we can argue about whether the iron here was the crucial feature as opposed to the sound, it does at least support that mass produced iron can be associated with protection. 
Its always best to remember that fairy is a general term, like animal, that applies to a wide array of beings. Iron is recommended as a superlative protection against fairies, but there will always be those who are not bothered by it. If we were to say that about 80% of fairies can't bear the touch of iron then the other 20% have no problem with it, and those would include mine faeries, forge spirits, and some house spirits; basically any fairy that would naturally exist or dwell near iron or iron ore. Also any of the aos sidhe connected to smithing don't seem to be bothered by iron.

3. Iron or Steel?

 Iron is hard to come by these days and although it is the best protection steel will also work in a pinch. Steel is between 90 and 98% iron depending on the alloy, so a steel object is obviously mostly an iron object. Iron and steel are effectively the same substance and have been treated that way in folklore and for apotropaic purposes historically, where we find references to both iron and steel being used to ward off fairies.  Generally the type of item isn't as important as the material in this case so anything made of iron that you can procure can be used for protective purposes. In tradition any worked iron can be used to ward against fairies including iron weapons, iron nails, iron horse shoes, iron scissors, iron fire tongs, etc.,. There’s no indication in folklore or anecdotal material that the form of the iron matters, only its presence. There is debate about whether it has to be hand worked iron or not, and I doubt that will ever be settled, but we have accounts of non-hand forged being used successfully.
Steel has the same effect as iron because steel is almost identical to iron in substance. Or put another way steel, while it has some other metals alloyed in it, is still mostly iron.

4. Cold Iron

Many people are familiar with the term 'cold iron' and associate it today with pure or simply worked forged iron - what is technically called 'pig iron' or 'crude iron'. There are also some who draw on role playing games to understand this concept and believe that cold iron is iron that was cold forged. While interesting these are decidedly modern views on the concept, relying in part on technology that didn't exist when some of the older references to cold iron were made. Historically the term cold iron was a poetic term for any iron weapon and is synonymous today with the term 'cold steel'. Grose's 1811 Dictionary of the Vulgar tongue defines cold iron as "A sword, or any other weapon for cutting or stabbing"; in modern parlance cold steel would refer to a gun or similar weapon. When you see a reference to cold iron it is talking about an iron weapon, usually a sword or knife.

5. Using Iron

There are several ways to use iron to protect yourself and your home from fairies, if it's needed. Lady Wilde suggested protecting infants from being taken as changelings by sewing a bit of iron into the hem of the child's clothes (Wilde, 1888). I was taught a modern version of this, where it was recommended that a steel safety pin be attached to a child's clothing, particularly sleepwear. Another commonly recommended protection for children and babies was to hang a pair of scissors, opened into the shape of a cross, above the cradle (Briggs, 1976). A horseshoe can be hung up over the door way, points up, which not only acts to ward off fairies but is also said to draw good luck. An iron knife or cross is also an excellent protection, either carried or hung up above the door or bed (Briggs, 1976). Robert Kirk in his 1691 treatise on the Good Neighbours mentions the practice of putting "bread, the Bible, or a piece of iron" in the bed of a woman giving birth to protect the infant from being stolen. In Welsh belief a knife, particularly of iron, was so effective a protection that should friendly fairies visit a home all knives were hidden from sight lest they be offended and if a traveling person was attacked by the Othercrowd he had only to pull his blade for them to disappear (Sikes, 1880). Another method found in Germanic and Norse traditions is to hammer an iron nail into a post near the doorway or alternately part of the door frame. Additionally it is said to be as effective to draw a circle using an iron nail or knife around what you want to protect (Gundarsson, 2007).

A more modern, but still useful method, is the use of iron water. Fill a small spray bottle with water and add iron filings, iron dust, or a piece of iron, and allow to sit for a few days. The water can be sprayed into a room or around the home as needed.
As always keep in mind that the use of iron will not effect all fairies, as some - including mine fairies and house fairies - are not bothered by it. For those that are sensitive to it, though, it is a superlative protection. 

To summarize; ultimately the amount doesn't seem to matter as long as the content is iron. The shape is also not important although it is more often recommended in a form that is sharp - a knife or nail - or combined with a holy symbol like a cross. The placement is best either on the person or very close by, especially near where they are sleeping. When placed above or next to an entrance it is believed that the presence of iron will keep out any Otherworldly beings. Although in today's world iron may be more difficult to find steel is fairly easily obtained and will work as well.

6. Fairies and Blood

There is an idea I have occasionally run across that the Good People would be or are averse to human blood because it contains iron. There are some anecdotal accounts which claim fairies have white blood and and are averse to or avoid the colour red and human blood (see: Fairy Faith in Celtic Countries and The Good People for more on this). However these are late 19th century and 20th century accounts which hinge on the Catholic belief that fairies have white blood because they are not mortal and have been denied Heaven/salvation and they avoid human blood not because it contains iron as some people are now alleging but because it represents the afterlife they are barred from. We also have a multitude of evidence that red is a colour associated with fairies and that many fairies are known to wear red which contradicts the idea that they would avoid that colour. While there is at least one anecdotal account, recorded by Lysaght in the Good People, of a belief that the Good Folk were averse to the color red and to blood, we see far more stories of fairies eating red meat, cooking bread with blood*, and in some cases eating humans even the ones who are averse to iron, so it doesn’t seem like blood and forged iron have the same effect.
Further to that point, the iron in human blood, aka hemoglobin, is not the kind that would ward against fairies anyway. Iron in human blood is a very miniscule amount; there’s only something like 4 grams total in a grown man altogether including blood, bone marrow, etc., Second of all hemoglobin is chemically different from ferrous iron which almost certainly makes a difference. 
In short - iron or steel in any form protects against fairies. Human blood does not.

7. Can Iron be 'Tamed'?

There are some modern magical practitioners that believe that iron can be rendered ineffective against the Good Folk, intentionally, by quenching it or washing it in a particular herb, often foxglove. This process is referred to as taming. The furthest back I can trace this idea in writing is to the 2005 book 'Viridarium Umbris' by David Schulke; the author cites no sources for the concept. I have talked to a few people who also believe and use this process, avow to its effectiveness, and existence before Schulke's book. All I can really say here is that it isn't anything found in Irish folklore or practice, or more generally in fairy folklore, and may be something particular to modern grimoire material. 

End Note
*this is from a story where a servant girl fails to leave out fresh water overnight for the Good Folk to cook with so they prick her and use her blood to make their bread instead, causing her to fall ill. Her health is restored only when she finds out what has happened and manages to get a piece of the bread for herself to eat. 

Reference:
Gundarsson, K (2007). Elves, Wights, and Trolls
Wilde, E., (1888) Irish Cures, Mystic Charms, & Superstitions
Briggs, K., (1976) A Dictionary of Fairies
Grose, F., (1811) Dictionary of the Vulgar Tongue
Sikes, W., (1880) British Goblins: Welsh folklore, Fairy mythology, Legends, and Traditions
Kirk, R., (1691) The Secret Commonwealth of Elves, Fauns, and Fairies
Narvaez, P (1991) The Good People
Evans-Wentz, W., (1911) Fairy Faith in Celtic Countries