Metal Magic: Heat Bluing Steel Clock Hands

Metalwork of any kind is fascinating stuff to watch. When the metalwork in question is in service of the clockmaker’s art, the ballgame changes completely. Tiny screws and precision gears are created with benchtop lathes and milling machines, and techniques for treating metals border on alchemy – like heat-bluing of steel clock hands for a custom-built clock.

If you have even a passing interest in metalwork and haven’t followed [Clickspring]’s YouTube channel, you don’t know what you’re missing. [Chris] has been documenting a museum-quality open-body clock build, and the amount of metalworking skill on display is amazing. In his latest video, he covers how he heat-blues steel to achieve a wonderful contrast to the brass and steel workings. The process is simple in principle but difficult in practice – as steel is heated, a thin layer of oxides forms on the surface, enough to differentially refract the light and cause a color change. The higher the heat, the thicker the layer, and the bluer the color. [Chris] uses a custom-built tray filled with brass shavings to even out the heat of a propane torch, but even then it took several tries to get the color just right. As a bonus, [Chris] gives us a primer on heat-treating the steel hands – the boric acid and methylated spirits bath, propane torch flame job and oil bath quenching all seems like something out of a wizard’s workshop.

We’ve covered [Chris]’ build before, and we encourage everyone to tune in and watch what it means to be a craftsman. We only hope that when he finally finishes this clock he starts another project right away.

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Jeri makes flexible EL displays

A failed chemistry experiment led [Jeri Ellsworth] to discover a flexible substrate for electroluminescent displays. We’re familiar with EL displays on the back of a glass panel like you would find in an audio receiver, but after making a mesh from aluminum foil [Jeri] looked at using the porous metal to host phosphors. She starts by cleaning foil and using a vinyl sticker to resist etching portions of the aluminum. It then goes into a bath of boric acid, electrified with the foil as the anode. As the foil etches she tests the progress by shining a laser through the foil. After this the phosphors are applied to the back surface of the foil, covered in a dielectric, and topped off with a conductive ink that will carry the AC necessary to excite the phosphors. This is layering materials in reverse compared to her EL PCB experiments. See [Jeri] explain this herself in the clip after the break.

You can see above that this produces a pretty well-defined display area. It reminds us of that color changing paint display. We think it would be worth a try to build a few 7-segment displays using this method.

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