Comment by notacoward | Hacker News Reader

Comment by notacoward | Hacker News Reader

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Strontium aluminate doped with europium has been the standard in persistent phosphorescence for a while. A large part of the reason I got into epoxy resin craft was to incorporate it in glowing elements, so I have a lot of such items. Some last all night. Some - especially reds and purples - are faint and barely last an hour. More recently, I've noticed dysprosium being added to the mix as well, though TBH I've never noticed any difference in brightness or duration compared to stuff I could get ten years ago.

The one thing I'd highlight (heh) for anyone trying to use this stuff themselves is: be aware of its density. I have yet to find a version that disperses evenly in resin; it tends to sink instead. Might disperse better in glass, but I know little about that craft so maybe it would be unusable for other (thermal?) reasons. If it tends to sink or float in any medium, such as paint, color/glow will be uneven. There are ways to deal with this issue, but they tend to involve extra steps. For example, with resin you can pour many thin layers, but if you want to avoid visible strata you have to go even further with non-planar surfaces and thickeners and such. It's ton of fun, but also a bit of work sometimes.

Might it suspend better/longer if the particle size were smaller?

I've ordered some, will try a little comminution to get fine dust. At some point, viscosity should predominate over settling.

per the docs at https://www.unitednuclear.com/glowdata.htm :

"Do no not grind the glow powder or try and dissolve it. On a microscopic level, the glow powder works by an energy exchange in its crystalline structure. These crystals are very small and just appear like a fine powder. When they are mixed with a clear medium as we do with our glow paint, the glow powder does not dissolve, it is just suspended in the medium. If you mix the powder with a medium that causes it to break down and dissolve (like water), the glow will be ruined. The same thing will happen if you grind the glow powder. You crush and destroy the crystal matrix and the energy will not be able to transfer between the glow material molecules causing a dramatic drop in glow brightness."

In my direct experience, grain size hasn't made much difference. Also, I use several kinds of very fine dusts/powders in my resin work and I've come to loathe the whole category. They go everywhere at the slightest puff of air, stick to equipment and tools, etc. I already wear a mask, but with chemical (NIOSH magenta or olive) rather than particulate cartridges, so there's that too. Of course YMMV. Perhaps also relevant is that I tend to work mostly with low-viscosity resins because it's easier wrt bubbles and edge creep, but I've had the settling problem even with higher-viscosity formulations. Maybe some day I'll hit on a combination of materials and techniques that solves the problem. Just hasn't happened yet. Good luck!

Care to share pictures of some of your creations...?

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