crystals

9 Articles

Growing Aluminium-Copper Alloy Crystals Using Hydrogen

April 20, 2026 by 2 Comments

Having molten aluminium interact with atmospheric water forms a source of hydrogen which can be rather problematic if you’re trying to cast aluminium parts. As the molten metal cools down, the dissolved hydrogen is forced out, creating bubbles and other flaws that make aluminium foundries rather upset. While you can inject inert gases to solve the problem, you can also lean into this issue to make some rather fascinating aluminium crystals and geodes, as [Electron Impressions] recently did.

The key here is to use a eutectic Al-Cu alloy at around 45% Cu by weight, as this alloy readily forms large crystals as it cools down. With hydrogen injected into the molten metal, this hydrogen forms large bubbles inside the cooling metal with crystals clearly visible.

A way to create proper geodes involves very slow cooling and pouring off the still molten metal before the eutectic point is reached. As can be seen in this video, this creates a rather impressive looking geode after it’s been smashed open. This also gives a good clue as to how these geological features form in nature, although one does not typically observe Al-Cu alloy geodes in the wild.

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All Inverters Are (Not) Created Equal

October 30, 2023 by 10 Comments

Building a crystal clock source for a CPU used to be a bit of an effort but these days, there’s nothing to it. Even if your CPU or other device needs an external clock, you just slap in an inverter, a crystal, and two capacitors together, and you are done, right? Maybe not. [Dave Collins] got interested in the common circuit and pulled out his scope and an array of different kinds of inverters. He looked at inverters and NAND gates and a few common circuit configurations.

This is one of those things you just assume is of little importance, but it turns out your choice of circuit architecture and active device can have a big impact on the output. But who has time to do all the testing? Thanks to [Dave] you don’t have to.

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How To Grow Your Own Pyramid Salt Crystals

October 13, 2022 by 22 Comments

The regular granular table salt you’re used to isn’t the most attractive-looking seasoning out there, even given its fundamentally compelling flavor. You don’t have to settle for boring old salt anymore though, because [Chase] has shown us you can grow your own pyramid salt crystals at home!

Pyramid salt crystals can grow naturally, and typically occur in locations where salt pools are undisturbed under the warmth of the sun. However, it’s possible to grow them on purpose, too. As a bonus, their hollow structure means they dissolve very quickly on the tongue, and can taste “saltier” than typical granular salt.

To grow your own, you’ll need a bag of salt, which is mixed with some water. You’ll want to do so in a glass dish, as the salty solution you’ll be making can ruin metal cookware. The dish can then be heated up on an electric hotplate, which is used to heat the solution to between 60 and 70°C.

A small amount of food-grade potassium alum is also added to the solution to calm the convection currents in the heated solution, allowing the crystals to form gently without sticking and clumping together. As the water boils away, the rectangular-pyramidal crystals grow.

Naturally, you must be careful before eating the results of any home-grown lab experiments. However, [Chase] reports having licked some of the crystals and has confirmed they do indeed taste salty. [Chase] also notes several ways in which the parameters can be changed to grow different types of pyramid crystals, too.

We’ve featured [Chase]’s crystal-growing work before. If you’ve got your own cool DIY crystal projects cooking up in the lab, be sure to let us know!

holding up the flavor stone

An Infinity Gem That Didn’t Make The Cut, The Flavor Stone

March 5, 2022 by 26 Comments

MSG (Monosodium Glutamate) is a flavor enhancer used to add a meaty/savory (often called umami) flavor to a dish. You might even have some in your pantry (though more likely it is in something that is in your pantry). What you might not know is that you can grow it into a large crystal.

[Chase] does an excellent job walking through the details of the process. MSG is one of the many common household substances that can grow into a crystal such as table salt, alum, fertilizer, sugar, or Epsom salt to name a few. The idea is quite simple —  just create a supersaturated solution with your desired crystal material and then suspend a string in it; but the execution has some nuance. To create a medium that’s super saturated, heat some water and mix in equal parts of MSG. Then let it cool once it has all dissolved and split it into two parts, one big and one small. You need to create a seed crystal, so place the small solution in a shallow dish and let a crystal percolate out over the new few days. You attach one of the seed crystals that grow to a string and suspend it in your solution. There are several gotchas around how to properly harvest the crystals but [Chase] enumerates them for you.

We’ve covered [Chase’s] efforts before when he grew crystals out of Rust. He is on a quest to grow all five flavor stones: salty, sweet, sour, umami, and bitter and we wish him all the best. What we would also love to see is the whole process of MSG from start to finish, making your own MSG.

The (Sodium Chloride) Crystal Method

November 20, 2021 by 25 Comments

[Chase’s] post titled “How to Grow Sodium Chloride Crystals at Home” might as well be called “Everything You Always Wanted to Know about Salt Crystals (but Were Afraid to Ask).” We aren’t sure what the purpose of having transparent NaCl crystals are, but we have to admit, they look awfully cool.

Sodium chloride, of course, is just ordinary table salt. If the post were simply about growing random ugly crystals, we’d probably have passed over it. But these crystals — some of them pretty large — look like artisan pieces of glasswork. [Chase] reports that growing crystals looks easy, but growing attractive crystals can be hard because of temperature, dust, and other factors.

You probably have most of what you need. Table salt that doesn’t include iodine, a post, a spoon, a funnel, filter paper, and some containers. You’ll probably want tweezers, too. The cooling rate seems to be very important. There are pictures of what perfect seed crystals look like and what happens when the crystals form too fast. Quite a difference! Once you find a perfectly square and transparent seed crystal, you can use it to make bigger ones.

After the initial instructions, there is roughly half the post devoted to topics like the effect growth rate has on the crystal along with many pictures. There are also notes on how to form the crystals into interesting shapes like stars and pyramids. You can also see what happens if you use iodized salt.

If salt is too tame for you, try tin. Or opt for copper, if you prefer that.

How To Make Resin Prints Crystal Clear

August 12, 2021 by 19 Comments

[Matou] has always been entranced by the beauty of natural crystal formations [and has long wished for a glowing crystal pendant]. Once he got a resin-based 3D printer, he was majorly disappointed to find out that although transparent resin prints look like delicious candy when they’re still wet, they turn cloudy and dull after being washed in an isopropyl bath and cured with UV light. There must be a way to either polish pieces back to clear, or keep them clear in the first place, [Matou] thought, and set about experimenting with some test crystals (video, embedded below).

As [Matou] found out, the dullness is caused by surface imperfections. Resin prints have layer lines, too, and although they may be super fine and invisible to the naked eye, they will still scatter light. The choices seem obvious — either polish the proud parts down with many grits of sandpaper, or fill the valleys with something to smooth everything out. As you’ll see in the video after the break, [Matou] tried it all, including a coat of the same resin that made the print. It’s an interesting look at the different ways to smooth out resin prints, though you may not be surprised to find that the one with the most work put into it looks the best.

We were hoping to see [Matou] try a green LED in the pendant, but it didn’t happen. If you’re dying to know what that looks like, you can get one of these pendants for yourself by supporting [Matou] on Patreon.

We think crystals are pretty cool, too — especially crystal radios. Here’s the hack-iest one of those we’ve ever seen, free of charge.

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A Beginner’s Guide To X-Ray Crystallography

January 21, 2020 by 6 Comments

In graduate school, I had a seminar course where one of the sections was about X-ray crystallography. I was excited, because being able to discern the three-dimensional structure of macromolecules just by shining X-rays on them seemed like magic to me. And thanks to a lackluster professor, after the section it remained just as much of a mystery.

If only I’d had [Steve Mould] as a teacher back then. His latest video does an outstanding job explaining X-ray crystallography by scaling up the problem considerably, using the longer wavelength of light and a macroscopic target. He begins with a review of diffraction patterns, those alternating light and dark bands of constructive and destructive interference that result when light shines on two closely spaced slits — the famous “Double-Slit Experiment” that showed light behaves both as a particle and as a wave and provided our first glimpse of quantum mechanics. [Steve] then doubled down on the double-slit, placing another pair of slits in the path of the first. This revealed a grid of spots rather than alternating bands, with the angle between axes dependent on the angle of the slit pairs to each other.

Photograph 51, an X-ray crystallogram of the B-form of DNA, by Gosling and Franklin, 1952. Source: Wikipedia

 

To complete the demonstration, [Steve] then used diffraction to image the helical tungsten filament of an incandescent light bulb. Shining a laser through the helix resulted in a pattern bearing a striking resemblance to what’s probably the most famous X-ray crystallogram ever: [Rosalind Franklin]’s portrait of DNA. It all makes perfect sense, and it’s easy to see how the process works when scaled down both in terms of the target size and the wavelength of light used to probe it.

Hats off to [Steve] for making something that’s ordinarily complex so easily understandable, and for filling in a long-standing gap in my knowledge.

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