How The Lost Mystery Pigment ‘Maya Blue’ Got Recreated

A distinct blue pigment reminiscent of turquoise or a clear sky was used by the ancient Maya to paint pottery, sculptures, clothing, murals, jewelry, and even human sacrifices. What makes it so interesting is not only its rich palette — ranging from bright turquoise to a dark greenish blue — but also its remarkable durability. Only a small number of blue pigments were created by ancient civilizations, and even among those Maya blue is unique. The secret of its creation was thought to be lost, until ceramicist and artist [Luis May Ku] rediscovered it.

Maya blue is not just a dye, nor a ground-up mineral like lapis lazuli. It is an unusual and highly durable organic-inorganic hybrid; the result of a complex chemical process that involves two colorants. Here is how it is made: Indigotin is a dye extracted from ch’oj, the Mayan name for a specific indigenous indigo plant. That extract is combined with a very specific type of clay. Heating the mixture in an oven both stabilizes it produces a second colorant: dehydroindigo. Together, this creates Maya blue.

Luis May Ku posing with Maya blue.

The road to rediscovery was not a simple one. While the chemical makeup and particulars of Maya blue had been known for decades, the nuts and bolts of actually making it, not to mention sourcing the correct materials, and determining the correct techniques, was a long road. [May] made progress by piecing together invaluable ancestral knowledge and finally cracked the code after a lot of time and effort and experimentation. He remembers the moment of watching a batch shift in color from a soft blue to a vibrant turquoise, and knew he had finally done it.

Before synthetic blue pigments arrived on the scene after the industrial revolution, blue was rare and highly valuable in Europe. The Spanish exploitation of the New World included controlling Maya blue until synthetic blue colorants arrived on the scene, after which Maya blue faded from common knowledge. [May]’s rediscovered formula marks the first time the world has seen genuine Maya blue made using its original formula and methods in almost two hundred years.

Maya blue is a technological wonder of the ancient world, and its rediscovery demonstrates the resilience and scientific value of ancestral knowledge as well as the ingenuity of those dedicated to reviving lost arts.

We’re reminded that paints and coatings have long been fertile ground for experimentation, and as an example we’ve seen the success people had in re-creating an ultra-white paint that actually has a passive cooling effect.

Origami-Inspired, Self-locking Structures With 3D Printing

Researchers recently shared details on creating foldable, self-locking structures by using multi-material 3D printing. These origami-inspired designs can transition between flat and three-dimensional forms, locking into place without needing external support or fasteners.

The 3D structure of origami-inspired designs comes from mountain and valley fold lines in a flat material. Origami designs classically assume a material of zero thickness. Paper is fine, but as the material gets thicker things get less cooperative. This technique helps avoid such problems.

An example of a load-bearing thick-film structure.

The research focuses on creating so-called “thick-panel origami” that wraps rigid panels in a softer, flexible material like TPU. This creates a soft hinge point between panels that has some compliance and elasticity, shifting the mechanics of the folds away from the panels themselves. These hinge areas can also be biased in different ways, depending on how they are made. For example, putting the material further to one side or the other will mechanically bias that hinge to fold into either a mountain, or a valley.

Thick-panel origami made in this way paves the way towards self-locking structures. The research paper describes several different load-bearing designs made by folding sheets and adding small rigid pieces (which are themselves 3D printed) to act as latches or stoppers. There are plenty of examples, so give them a peek and see if you get any ideas.

We recently saw a breakdown of what does (and doesn’t) stick to what when it comes to 3D printing, which seems worth keeping in mind if one wishes to do some of their own thick-panel experiments. Being able to produce a multi-material object as a single piece highlights the potential for 3D printing to create complex and functional structures that don’t need separate assembly. Especially since printing a flat structure that can transform into a 3D shape is significantly more efficient than printing the finished 3D shape.

The Stern-Gerlach Experiment Misunderstood

Two guys — Stern and Gerlach — did an experiment in 1922. They wanted to measure magnetism caused by electron orbits. At the time, they didn’t know about particles having angular momentum due to spin. So — as explained by [The Science Asylum] in the video below — they clearly showed quantum spin, they just didn’t know it and Physics didn’t catch on for many years.

The experiment was fairly simple. They heated a piece of silver foil to cause atoms to stream out through a tiny pinhole. The choice of silver was because it was a simple material that had a single electron in its outer shell. An external magnet then pulls silver atoms into a different position before it hits some film and that position depends on its magnetic field.

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Chirality Could Kill Us All, If We Let It

In our high school chemistry classes we all learn about chirality, the property of organic molecules in which two chemically identical molecules can have different structures that are mirror images of each other. This can lead to their exhibiting different properties, and one aspect of chirality is causing significant concerns in the field of synthetic biology. The prospect of so-called mirror organisms is leading to calls from a group of prominent scientists for research in the field to be curtailed due to the risks they would present.

Chirality is baked into all life; our DNA is formed of right-handed molecules while our proteins are left handed. The “mirror” organisms would reverse either or both of these, and could in theory be used to improve biochemical production processes. The concern is that these organisms would evade both the immune systems of all natural life forms, and any human defences such as antibiotics, thus posing an existential risk to life. It’s estimated that the capacity to produce such a life form lies more than a decade away, and the scientists wish to forestall that by starting the conversation early. They are calling for a halt to research likely to result in these organisms, and a commitment from funding bodies not to support such research.

Warnings of the dangers from scientific advances are as old as science itself, and it’s safe to say that many such prophecies have come from dubious sources and proved not to have a basis in fact. But this one, given the body of opinion behind it, is perhaps one that should be heeded.

Header: Original: Unknown Vector: — πϵρήλιο, Public domain.

Automated Rig Grows Big, Beautiful Crystals Fast

We haven’t seen [Les Wright] in a while, and with the release of his new video, we know why — he’s been busy growing crystals.

Now, that might seem confusing to anyone who has done the classic “Crystal Garden” trick with table salt and laundry bluing, or tried to get a bit of rock candy out of a supersaturated sugar solution. Sure, growing crystals takes time, but it’s not exactly hard work. But [Les] isn’t in the market for any old crystals. Rather, he needs super-sized, optically clear crystals of potassium dihydrogen phosphate, or KDP, which are useful as frequency doublers for lasers. [Les] has detailed his need for KDP crystals before and even grown some nice ones, but he wanted to step up his game and grow some real whoppers.

And boy, did he ever. Fair warning; the video below is long and has a lot of detail on crystal-growing theory, but it’s well worth it for anyone taking the plunge. [Les] ended up building an automated crystal lab, housing it in an old server enclosure for temperature and dust control. The crystals are grown on a custom-built armature that slowly rotates in a supersaturated solution of KDP which is carefully transitioned through a specific temperature profile under Arduino control. As a bonus, he programmed the rig to take photographs of the growing crystals at intervals; the resulting time-lapse sequences are as gorgeous as the crystals, one of which grew to 40 grams in only a week.

We’re keen to see how [Les] puts these crystals to work, and to learn exactly what a “Pockels Cell” is and why you’d want one. In the meantime, if you’re interested in how the crystals that make the whole world work are made, check out our deep dive into silicon.

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Silicon Carbide May Replace Zirconium Alloys For Nuclear Fuel Rod Cladding

Since the construction of the first commercial light water nuclear power plants (LWR) the design of their fuel rods hasn’t changed significantly. Mechanically robust and corrosion-resistant zirconium alloy (zircalloy) tubes are filled with ceramic fuel pellets, which get assembled into fuel assemblies for loading into the reactor.

A 12' SiGa fuel assembly, demonstrating the ability to scale to full-sized fuel rods. (Credit: DoE)
A 12′ SiGa fuel assembly, demonstrating the ability to scale to full-sized fuel rods. (Credit: DoE)

Now it seems that silicon carbide (SiC) may soon replace the traditional zirconium alloy with General Atomics’ SiGa fuel cladding, which has been tested over the past 120 days in the Advanced Test Reactor at Idaho National Laboratory (INL). This completes the first of a series of tests before SiGa is approved for commercial use.

One of the main advantages of SiC over zircalloy is better resistance to high temperatures — during testing with temperatures well above those experienced with normal operating conditions, the zircalloy rods would burst while the SiC ones remained intact (as in the embedded video). Although normally SiC is quite brittle and unsuitable for such structures, SiGa uses a SiC fiber composite, which allows it to be used in this structural fashion.

Although this development is primarily part of the Department of Energy’s Accident Tolerant Fuel Program and its focus on melt-down proof fuel, the switch to SiC could also solve a major issue with zirconium, being its use as a catalyst with hydrogen formation when exposed to steam. Although with e.g. Fukushima Daiichi’s triple meltdown the zircalloy fuel rods were partially destroyed, it was the formation of hydrogen gas inside the reactor vessels and the hydrogen explosions during venting which worsened what should have been a simple meltdown into something significantly worse.

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Holograms: The Art Of Recording Wavefronts

The difference between holography and photography can be summarized perhaps most succinctly as the difference between recording the effect photons have on a surface, versus recording the wavefront which is responsible for allowing photographs to be created in the first place. Since the whole idea of ‘visible light’ pertains to a small fragment of the electromagnetic (EM) spectrum, and thus what we are perceiving with our eyes is simply the result of this EM radiation interacting with objects in the scene and interfering with each other, it logically follows that if we can freeze this EM pattern (i.e. the wavefront) in time, we can then repeat this particular pattern ad infinitum.

Close-up of the wavefront pattern recorded on the holographic film (Credit: 3Blue1Brown, YouTube)
Close-up of the wavefront pattern recorded on the holographic film (Credit: 3Blue1Brown, YouTube)

In a recent video by [3Blue1Brown], this process of recording the wavefront with holography is examined in detail, accompanied by the usual delightful visualizations that accompany the videos on [3Blue1Brown]’s channel. The type of hologram that is created in the video is the simplest type, called a transmission hologram, as it requires a laser light to illuminate the holographic film from behind to recreate the scene. This contrasts with a white light reflection hologram, which can be observed with regular daylight illumination from the front, and which is the type that people are probably most familiar with.

The main challenge is, perhaps unsurprisingly, how to record the wavefront. This is where the laser used with recording comes into play, as it forms the reference wave with which the waves originating from the scene interact, which allows for the holographic film to record the latter. The full recording setup also has to compensate for polarization issues, and the exposure time is measured in minutes, so it is very sensitive to any changes. This is very much like early photography, where monochromatic film took minutes to expose. The physics here are significant more complex, of course, which the video tries to gently guide the viewer through.

Also demonstrated in the video is how each part of the exposed holographic film contains enough of the wavefront that cutting out a section of it still shows the entire scene, which when you think of how wavefronts work is quite intuitive. Although we’re still not quite in the ‘portable color holocamera’ phase of holography today, it’s quite possible that holography and hologram-based displays will become the standard in the future.

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