Would a glass sword be plausible and useful?

Question

Though glass knives existed and are still used in modern electron microscopy, glass is known for its brittleness and a sword needs to be able to parry an attack. But the idea of a transparent glass sword is very appealing aesthetically to me.

So if plausible, in what ways would a glass sword be useful in an alternate 19th century setting where gun ownership began to rise? Can it be reinforced with other materials? Is it possible to be a weapon of assassination or is it only possible to be a ceremonial weapon?

Answer 1

Blades are made of metal, even though metal isn't as hard as some minerals, because metal is tough. Hardness is a term in material science that represents the amount of energy it takes to cause an object to deform. Toughness is a term that represents that amount of energy it takes to cause an object to fracture.

In comparing fracture toughness, we see that Aluminum is perhaps 20x as tough as glass, while steel more like 50x as tough.

There are very tough glasses out there, but they will never be as tough as metals. Here is one company that advertises a mostly transparent glass/ceramic product. They don't advertise the fracture toughness of the material (because it is low) and instead concentrate on hardness, bending strength, and stiffness (which are comparable to steel). The best their ceramic products do is 7 MPam$^{1/2}$, which is about 1/3 of Aluminum and 1/7 of steel.

So there do exist transparent glass products out there, reinforced with Silicon Nitride, that take 3 times less energy to break than aluminum and seven times less energy to break than a regular old steel knife.

What does this mean? Well for stabbing a squishy meat-bag of a human, they will do just fine and be quite fatal. But if the person is wearing some sort of armor underneath their clothing, these hardened glass knives are as likely to punch through the armor as steel (because they are just as hard and stiff) but seven times more likely to break while trying to punch through.

So I guess the answer is...maybe?

Answer 2

It would presumably be less practical than the Aztec Macuahuitl, unless those reinforcements are amazingly effective.

• A solid core with glass edges might be the most practical solution, but of course this goes against your desired visual effect.
• It might be limited to a single stab, not a fencing duel where blades clash repeatedly. That sounds like an assassin's tool, but unlike a dagger a longer sword would be hard to hide.
• In a world prior to metal detectors, a non-metallic sword would be no easier to hide than a metallic one.

Answer 3

Synthetic sapphire

What you want from your glass sword is aesthetics; it doesn't seem essential that it be technically a form of glass. What I propose is actually a crystal.

Sapphire is the pure crystalline form of (otherwise very common) aluminium oxide. It is extremely hard -- much harder than steel, and nearly as hard as diamond -- and quite tough. It isn't as tough as steel, but similar to cast iron, and very much tougher than glass. It is also much more resistant to high temperatures than steel, so at white heat it is actually tougher than steel. And it is -- or can be made -- water clear, far more transparent than ordinary window glass. It is about half the density of steel: light, but still much denser than glass, plastics, or light alloys, so perhaps making for a sword that it fairly lightweight, but has some heft for powerful blows. Alternatively, the lower density could be "spent" on making the blade thicker and wider, for greater strength.

It's no surprise that natural sapphire is a prized gemstone, but in the mid-twentieth century, we learned how to make synthetic sapphire fairly economically. By the end of the twentieth century the technology had progressed to the point where we could make huge synthetic sapphires -- potentially sword sized, perhaps even bigger.

Although this technology was developed well after your period, the basic tool required -- the hydrogen blowtorch -- did exist in the nineteenth century, and it is quite plausible that in an alternative timeline, synthetic sapphire may have been discovered far earlier.

Why would someone want a sapphire sword? One or more of the following reasons might apply:

• Use at very high temperatures (how the wielder survives is an exercise left to you!);
• Superior corrosion resistance in many environments (but not in alkalis, which damage it rapidly);
• Not affected by magnetic fields or electric currents;
• Superior hardness and extreme sharp edges (but the very devil to re-sharpen if you damage the edge);
• Coolness for a social elite: the hoi polloi can have their common steel pig-stickers; us gentry use only the purest crystal swords.

Answer 4

Let's use obsidian for our starting point. Obsidian has been and still is used for knives. These knives are poorly shaped, and in modern times only used in low impact high detail settings. It is unsuitable for making a sword or pretty knife.

Then there's regular pane glass. These shards can be very sharp, but tend only to exist in large but fragile broken shapes. you could create a shaped blade by etching the glass and breaking it out, but it would be very useless and look bad. You could also mold it into the shape of a weapon, but it would risk breaking and hurting yourself and could only be ceremonial. (Depending on the material glass can be a number of colors, but all tend to have the same properties as the most common silicon variety.)

Next we have tempered glass. Oh beautiful tempered glass. Take the mold from the regular glass and make sure there's a wide flat blade with a sharp tip and a sturdy handle. Temper it into safety glass of the highest kind, or at least a moderate temper. the idea is that a wide flat blade can be easily snapped, rupturing the temper and causing the blade to become a bunch of glass shards inside of any assassination target. Good luck saving them. Plus, the handle will crumble away, and provided you wrapped it in a cloth or wore a glove to protect your hand, there will be no physical evidence to trace back to you except a bunch of small bits of glass. If you forget to protect your hand you may get some small cuts.

Answer 5

In Brandon Sanderson's Mistborn series glass daggers were a weapon of choice for certain fighters. The reason was simple: some people could manipulate any metals, thus any metal armour was impractical. Metal weapons were out too for the same reason, so all you were left with were either wooden weapons, or something brittle (glass, bone, etc). Since wood alone isn't that good for cutting, you used glass. And since your opponents typically had no armour, glass was practical even for open confrontations, not merely assassinations.

In other words, make metal unsuitable for combat for some reason, and you will find glass weapons useful.

Of course, those still were daggers, not swords, as you wouldn't want to parry with them.

Answer 6

You said you are interested in it for aesthetics. Therefore, I'm going to go with an answer that explains why glass weapons exist without them necessarily being the most practical weapon. I think the glass sword would be:

The weapon of choice for a gentleman's duel to the death.

Gentlemen have to have a good way to have a duel to the death after all, and when it comes to such things the ideal weapon is a weapon the requires real skill, and not necessarily because it is practical. I'm imagining that in your world a short glass sword (glass dagger/rapier?) has become the weapon of choice to permanently settle matters of honor, and all such fights are fights to the death. The duel itself has evolved to account for the ease with which a glass dagger can break. Some thoughts off the top of my head:

1. Intentionally breaking an opponents sword is considered dishonorable
2. Finishing the duel, dispatching your opponent, and doing it without breaking your own sword is considered an especially impressive victory.
3. There will no longer be any parrying at all - doing so will obviously be an easy way to break your sword
4. Stabbing will be the goal. You could probably build a cutting edge with a glass sword, but slicing your opponent will probably have a high chance of breaking your sword.

I'm trying to figure out what such a duel might look like:

1. If there is an edge on the blade, I could imagine there being special gauntlets/armor worn on the arms that are used to deflect a stab/cut from the opponents weapon. Perhaps this is the only armor that combatants are allowed to wear.
2. Presuming that the weapon is for stabbing only, I imagine a shorter blade will be preferable so that you can stab and then pull your weapon out of your opponent quickly, minimizing the chances of your weapon breaking if your opponent moves/falls.
3. Good aim and knowledge of anatomy will be important - hitting an opponent's bone may kill them (depending on what else you hit) but probably has a much higher chance of breaking your sword.
4. Allowing your sword to be broken would be considered poor form because at that point in time your only recourse is to effectively beat your opponent to death, and that is neither skillful nor honorable.
5. If both opponents break their swords then you basically have two men trying to beat each other to death with their bare hands. Perhaps the relative "indignity" of this act leaves even the victor in a state of dishonor.
6. As a result, the goal may be to end the match with a single quick thrust into vital areas/organs, quickly and painlessly (relatively speaking) killing your opponent with a minimum of fuss. After all, that is the only way an honorable gentleman would kill another (irony intended).
7. Depending on weapon length I could see this leading to a match that is effectively a grappling contest, with each contestant trying to line up their "sword arm" for a single quick and clean stab into just the right soft spot on their opponent...

I'm not even a fan of violence but I almost want to watch such a match myself :) Glass swords: the weapon of choice for a gentleman when the court system is not available to give you the "justice" you deserve.

Answer 7

Pure glass through and through wouldn't work in the traditional way we use blades, as while its sharpness is very much comparable, the flexibility is nowhere near what steel's is. However! If you slightly change the way you think of swords, the Macuahuitl is a club that has been embedded with obsidian shards and used like a wakizashi (pull edge across skin, not poke or hack). It's not going to survive an actual swordfight without further alteration, but as a close-combat weapon, it would produce deep lacerations if slid over skin or armor.

Answer 8

Mayhaps a "Prince Rupert's Drop type construction so the sword shatters instantaneously into 'dust' when stressed at the appropriate location but, until then, is "reasonably strong".

Obtaining a "sword shaped" Prince Rupert's drop 'may take some work'.

Applications might include -

• Causing a weapon to vanish after it has been used to commit a dastardly deed.

• Poison or other substance delivery system - an aerosol cloud is generated when the sword self-dismantles.

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Stills from this Youtube video

Frame at 1m46s - Head end is "sharp hammer head proof"

But "tweak the tail" and it explodes. (1m51s)

Answer 9

The question was pertaining to swords, but hinted also interest as an assassin´s weapon: As an assassin´s weapon of choice it would do wonders! My history teacher told us about the venician glass daggers. But i could only find references in fiction: for example "The Glassblower of Murano". Maybe an italian speeker can help out =).

The idea of glass stilletos is so interesting because they are expensive to make -> sending a message, take great skill to use -> brittleness, and make the victim suffer,a lot. Since hitting anything remotely hard, breaks the weapon and it is almost impossible to remove the tiny shards completely, also the . Think about a certain Superhero with a magnet in his chest, but the magnet being useless.

Answer 10

Libyan Desert Glass
Like obsidian, it was knapped and used to make tools during the Pleistocene. (It has a sleek, honey yellow colour.)

From the Wikipedia article:

The glass is nearly pure silica which requires temperatures above 1,600 °C to form – hotter than any igneous rock on Earth. However, few mineral relics survived from whatever caused the melting, including a form of quartz called cristobalite, a rarely occurring high-temperature mineral; and grains of the mineral zircon, although most have reacted to form a higher-temperature mineral called zirconia. Ideas about how the glass formed include melting during meteorite impact, or melting caused by an airburst from an asteroid or other object burning up high in Earth's atmosphere.

Moldavite

From the Wikipedia article:

Moldavites were discovered by prehistoric peoples in the Czech Republic and Austria and were used to make flaked tools. Some of the worked moldavites date to the Aurignacian period of the Upper Paleolithic, approximately 43,000 to 26,000 years before the present.

In the modern world, moldavites are often used, rough or cut, as semi-precious stones in jewelry. They have purported metaphysical qualities and are often used in crystal healing.

The chemical formula of moldavite is SiO2(+Al2O3).

This means it's a silica glass. (It has a gorgeous array of green colours, from forest green, olive green to a unique blue greenish).

If this glass was in high use, and rare (cause, you know, meteors strike Earth everyday.. ;P) AND a highly influential family/group found it.. Glassworking practices may take a step for that world, due to the "prestige" of owning the only (functional) "Glass" Weapons of the planet. Eventually, other deposits would be found on Earth, then other cultures would attempt to copy the glassblowing techniques, either succeeding, failing, or inventing entirely new methods to glassworking.

Would it be useful?
Depends on the technological standards of your world, and WHY certain practices may have been focused on. If a high quality glass based on the above two real life glasses could be worked into a more solid and secure molecular form so that it wasn't as easy to break, chip, or damage after the weapon/tool/item was shaped and created, then possibly.

BUT. How did that happen?
That's the big Sci-Fi question.

Answer 11

If bullet proof glass exists, then I think there is at least some kinds of glass that can be used as a traditional weapon. Remember that even when using swords, wielders try to avoid clashing weapons. So if the glass is bullet proof, and is only impacting soft flesh as per the 19th century soldier types where heavy armor was not common, then I don't see a problem with using glass weapons.

The technology and manufacturing process might not exist in this time period however.