Probing the properties of Spider-Man’s web fluid

Hello readers! Usually, I don’t like to talk about superhero media on this blog, because it belongs in its own genre, separate from traditional fantasy and science fiction. However, today I am making an exception – all because of a two-minute scene in Spider-Man: Brand New Day (2026). I went to see this film a few weeks ago, right after it came out, and thought it was pretty good. I enjoyed it. But I was caught off-guard when, out of nowhere, one of the characters asked Spider-Man whether his webs were a “shear-thinning fluid”.

Now, I know this “shear-thinning” line was probably ignored by most people. We’ll get to that. But as someone with a background in fluid dynamics, I recognised this term – and it got me thinking. What are the fluid properties of Spider-Man’s webs? And could such a combination of properties exist in the real world?

Firstly, let me explain my surprise

I would hazard a guess that “shear-thinning fluid” means nothing to 99.99% of the audience of this film. And the writers probably didn’t want the audience to understand it: they just needed some sciency-sounding term to make a nerdy character sound even nerdier. We’re meant to believe that Spider-Man and his friends are super intelligent, after all.

However. As one of the few people watching this film who DID recognise this terminology, let me tell you: this is a rare event. This might even be the first time that I have ever heard rheological terms make their way into a blockbuster film.

And what’s rheology…?

Rheology is the study of fluid flow, particularly focussing on complex fluids such as particle suspensions, foams or emulsions. It’s a pretty niche branch of research, despite having almost universal relevance across the physical sciences, from engineering to Earth science to biology. Most fluids don’t flow in a simple manner, and scientists need some way to quantify their behaviour. If you want to calculate how quickly mud can flow along a pipe, or how prone it is to jamming, you need rheology. If you want to calculate how far a jet of fire-fighting foam can travel before breaking into droplets, you need rheology. And, of course, if you want to ponder the real-world feasibility of Spider-Man’s webs, you need rheology.

Without giving away too much about my real-world job, I can tell you that I dabble with shear-thinning fluids. I’d even class myself as a rheologist on certain days of the week. I’ve been rheology conferences, published papers in rheology journals, and listened to various scientists talking about shear-thinning fluids. And when I heard this term in a Marvel film, I was astounded. Recognition for rheologists? Hell yeah.

But then, after a few seconds of consideration, I was intrigued. Is Spider-Man’s web fluid really shear-thinning? What properties does it have, to behave in the way that we see in the films?

Step 1: Let’s list the facts

We know that Spider-Man refers to his chemical concoction as “web-fluid”, and that he can shoot it out of tiny capsules on his wrists. However, although he calls it a “fluid”, it clearly behaves like a solid once extruded. One strand can suspend several tons of mass without breaking or stretching; indeed, Spider-Man has used his webs to stop speeding trains on more than one occasion.

We also know that the web fluid is sticky, as it can attach to most surfaces. It is slightly stretchy, and very strong – but it also dissolves in air after two hours. Another important point, which I haven’t seen mentioned anywhere else, is that the fluid can be fired in a clean arc over tens of metres without breaking up in wind currents or from its own surface tension. This is a crucial property; if you fired a typical fluid over such distances (e.g., water from a water pistol), you would expect it to break up into droplets in the air.

Based on these observations, it seems that the “web fluid” is only a fluid initially, when it is fired from the web-shooters. It soon becomes an elastic solid, which allows it to travel through the air and to support great weights without breaking. This means that the fluid must undergo some sort of crystallisation, drying, or curing process as it exits the web shooters.

Step 2: Possible contenders?

The precise recipe for web fluid unknown; we briefly see some of Peter Parker’s notes in Spider-Man: Homecoming (2017), but this is a list of fake chemistry nonsense. The ingredients include salicylic acid and “touline” (misspelt – it should be toluene), which Peter would struggle to find in a high-school chemistry lab. Not to mention that some of the chemicals are quite dangerous… You wouldn’t want them sticking to your bare skin.

In Brand New Day, a character suggests that the web fluid might be a polymer solution, meaning that the webs are made from a synthetic fibre such as nylon. Synthetic polymers are a good contender for man-made webs; fibres like nylon are strong and stretchy, and can be made through liquid-based chemical reactions, then spun out into threads.

In fact, making nylon is a simple and relatively common chemistry demonstration (see the Royal Society of Chemistry tutorial I have linked at the end of this post), and there are videos on YouTube pointing out the similarity to Spider-Man’s webs. The reaction involves two liquid layers that can’t mix, with a film of nylon forming at the interface between them. The nylon can be extracted into a thin filament – one which looks remarkably “webby” – but it could never be used in this state. It still holds too much liquid, isn’t particularly sticky, and is covered in toxic chemicals.

So, if Spider-Man is creating synthetic polymer threads with his web-shooters, he presumably isn’t making nylon – at least, not using the chemistry demo method!

What’s real spider silk made from?

The properties of web fluid should mimic those of natural spider silk – so you might be wondering why Spider-Man doesn’t just make a synthetic version, or borrow the natural chemicals and make it himself. The strength would need to be scaled up, of course, because the threads have to hold the several tons of mass, rather than just the mass of a spider. But is this possible?

The simple answer is no. Like all products of the natural world, spider silk is very complicated – a product of millions of years of evolution. The silk is mostly made of protein fibres, in the form of repeating chains of amino acids, and spiders can vary the types of protein and their extrusion method to make different threads for their various needs. Webs require different properties to cocoons, which require different properties to the threads used for wrapping prey. It’s a marvel of micro-scale biological engineering.

Inside the spider’s body, the web is stored in liquid form, containing water. Then, as soon as the web fluid is extruded from the spider, the water is removed and the protein chains form a solid thread. This process is facilitated by the spider’s “spinning ducts”, which are exactly the right shape to arrange the proteins into repeating patterns, giving the silk its incredible strength. By its strength-to-weight ratio, spider silk out-performs steel and Kevlar – but making a thread thick enough to hold a human would be incredibly difficult. The “spinning ducts” on a spider are the perfect size for the fluid; you can’t just make a bigger version and expect bigger results.

Step 3: Can we make synthetic spider silk?

Scientists have been trying for decades to reproduce the properties of spider silk under lab conditions, but this has proven incredibly difficult. The first obstacle to overcome is getting the liquids to react at the right moment. Somehow, spiders keep their silk ingredients separate until the exact moment they are needed – if they were mixed together too early, they would solidify inside the spinning duct. So, if Spider-Man is making synthetic spider silk with his web-shooters, he has some seriously complicated technology, well beyond anything that currently exists!

That’s not to say that synthetic spider silk is impossible. Some of the most promising results come from the “Silklab” at Tufts University, Massachusetts, whose research is funded by the US Office of Naval Research, among others (hopefully we won’t see soldiers with web-shooters any time soon). Last year, scientists at Silklab created “easily deployable hydrogel fibres possessing adhesive properties that can be released on demand to capture and retrieve loads from a distance” – which, at first glance, seems to be a perfect description of Spider-Man’s web fluid. However, the longest fibre they created with their web-shooter was only 18 cm long, and the best retrieval they could manage was a 5 g block of wood at a distance of 12 cm. The technology isn’t quite at Spider-Man levels yet – but it’s a promising start!

One of the most interesting aspects of their paper, which was published in Advanced Functional Materials (find the link at the end of this post), was the way they tuned the balance between liquid and solid properties. The web could only be shot out of the device and adhere to surfaces as a liquid, but it could only lift objects once it was solid. So, the timing of solidification was very important, and could only happen once the fluid made contact with the target object – which depended on the distance between the object and the web-shooter!

This raises an interesting conundrum. If the web has to be liquid in order to adhere to surfaces, that means it must remain liquid in the air, as an unsupported jet. And this places some severe restrains on the distance it can travel, because – as mentioned earlier – liquid jets break up into droplets due to wind currents and surface tension. Based on what we see from Spider-Man, his webs are solid before they make contact with their target. This means that his web fluid is very different to the Tufts web fluid.

What does “shear-thinning” have to do with anything?

After all this research, we haven’t even talked about shear-thinning, or why this was mentioned in the film. Is this a key property of Spider-Man’s webs? I think the answer is probably no – but let me explain.

If a fluid is shear-thinning, its viscosity decreases as shear rate increases. In other words, it gets runnier the faster you stir it. This is different from water, which always has the same viscosity no matter what you do to it (we call this a Newtonian fluid). Shear-thinning fluids are quite common, especially for particle suspensions, foams and emulsions. You might have come across this type of fluid behaviour with paint – it’s goopy in the tin, but then flows easily when you brush it onto a surface.

So, would shear-thinning properties be useful for Spider-Man’s web fluid? It might be helpful for the fluid to gain a lower viscosity as it was extruded from the web-shooters, to help it exit the tubes before it turns solid. However, if I’m to be very pedantic, once the fluid has exited the web-shooters, it is likely to be experiencing extensional flow (i.e., stretching) rather than shear flow (i.e., flow across a surface), meaning that the dynamics will be subtly different. In fact, you can have two fluids with identical shear properties, but completely different extensional properties. The fact that a fluid is shear-thinning doesn’t automatically make it suitable for all of Spider-Man’s webby needs.

If rheology is a niche field, then extensional rheology is a niche within that niche. In fact, there is a sub-group of rheologists who focus specifically on the extensional fluid properties of polymer solutions. Long, chain-like molecules imbue fluids with an elasticity that is particularly apparent in extensional conditions – such as when squirting fluid from a web shooter. The elasticity of polymer solutions can even counteract surface tension effects, and stop the fluid breaking up into droplets in mid-air. This is exactly what Spider-Man is after, as it would give his web fluid more time to convert from a liquid into a solid.

Conclusion: Web fluid is a polymer solution of some kind!

We can’t know for sure what type of polymer solution Spider-Man is using. It probably isn’t nylon. But whether he is borrowing actual spider proteins, or making a synthetic copy, he will be utilising long-chain molecules that create a fluid with elastic properties, which then solidifies in mid-air, before it meets its target. This fluid is very likely to be shear-thinning, but unfortunately, that description doesn’t tell us the whole story! In fact, it tells us very little about the web properties and dynamics.

I think the term “shear-thinning” only ended up in the film script because the writers were looking for sciency-sounding words to describe polymer solutions. They did enough research to learn that spider-webs and nylons are polymer chains, and then they looked up other properties and found shear-thinning behaviour. I doubt that they put this past a scientific adviser – and if they did, it is highly unlikely that they were a rheologist, because there simply aren’t very many of us!

In summary…

I hope you enjoyed this pointless investigation into an imaginary fluid. Maybe you learnt some new words, or discovered a new branch of science? Rheology often feels like a science without a home, because it accommodates researchers from all sorts of areas: physicists, engineers, Earth scientists, chemists, biologists… You can’t do a degree in rheology, so it ends up being a subject people learn at master’s level or beyond – often by accident! I wish we could teach children more about fluid properties in schools – it’s such an interesting field!

Happy reading, and have a lovely week!

Links:

Apologies if you can’t access these scientific articles for free. Unfortunately, that is just the miserable state of academic publishing…

Making nylon: Royal Society of Chemistry: https://edu.rsc.org/experiments/making-nylon-the-nylon-rope-trick/755.article

A nice review paper about spider silk: Omenetto, F.G. and Kaplan, D.L., 2010. New opportunities for an ancient material. Science, 329(5991), 528-531. https://doi.org/10.1126/science.1188936

Scientists making actual web fluid: Presti, M.L., Portoghese, M., Farinola, G.M. and Omenetto, F.G., 2025. Dynamic adhesive fibers for remote capturing of objects. Advanced Functional Materials, 35(4), 2414219. https://doi.org/10.1002/adfm.202414219

Videos of the web fluid experiments, and a good summary of the published paper: https://now.tufts.edu/2024/10/10/inspired-spider-man-lab-recreates-web-slinging-technology