19. Notes On Hyperbolic Blue Paint

(Read post 3, “Secret Colors, Impossible Colors”, first, or this will probably not make as much sense.)

You know how sometimes you set out to do something and you psych yourself up to put a lot of effort in to have to figure out precisely how to achieve some desired goal or effect, and then the very first thing you try approximately works? Yeah, that’s about what happened when I set out to mix my own hyperbolic blue paint. It turned out to be such a straightforward effect to achieve under fairly permissive lighting conditions that I’ve shown it off to easily dozens of people, and easy enough to make that I led a small group in making some in person at a small event in March 2025. For the sake of posterity, I’ll provide a short recipe here.

You will need the following:

• Synthetic ultramarine pigment (~$1/10 g)
• “Blue Lit” phosphorescent pigment, by Stuart Semple (~$20/50 g)
• A paint base, like linseed oil or acrylic base
• (Optional) Kaolin powder
• A small scale
• A mixing vessel, anything from a plastic cup to a pestle
• (Optional) A glass pigment grinder (called a muller)
• (Optional) Paint tubes, a paint brush, and a canvas 

The recipe is pretty straightforward. First, you want a mass ratio (this is what the scale is for) of roughly 7:1 Blue Lit to ultramarine, though I’ve had ratios anywhere from 5:1 to 11:1 work just fine. Ultramarine is an extremely powerful paint pigment, and we won’t need much; not for nothing did people once literally buy expensive rocks from Afghanistan to crush up. We’re luckier with our synthetic chemistry these days, and in fact synthetic ultramarine is actively better: the grain size of the powder is smaller and more even, and there are few if any impurities to impede the strong deep blue color. On the other hand, Blue Lit is notable for being activatable with visible light exposure and not just ultraviolet, but you need relatively quite a lot of it in order to get the glow to come through sufficiently. At this step, if you want to grind the powder even finer, mix the two together first, then lay them out on wax paper or the like and grind in gentle but firm circles with the muller. This is also when you would add a sprinkle of kaolin, for light dispersion. In any case, add the powder mix to the mixing vessel. Then, add sufficient medium - the paint base - to get the desired consistency. You likely want to aim for something like toothpaste here; if it’s too runny, use a bit of kaolin or Blue Lit powder. You can check the ratio at this stage by exposing the paint to sufficient visible or UV light - the powder doesn’t need to be bound to work. At this point, you’re technically done, but I’ve found it helpful to have paint tubes on hand for storage, and a paintbrush and small canvas for immediate sampling.

Now for some notes on best practices for displaying the result, so as to best produce the experience of hyperbolic blue. First, visible light takes longer to charge the paint than UV light does. With a bright visible light like a headlamp held maybe half a meter away, a canvas with two coats of hyperbolic blue paint will take ~30 seconds to start being displayable and plateaus after ~10 minutes; for UV, it takes maybe ~10 seconds to start being displayable and plateaus after ~5 minutes. More important is the ambient lighting conditions: my rule of thumb is that ideally, there should be just barely enough light to read by, not much more nor less. Ordinary room lighting (or, say, standard outdoor lighting and firepit light) will completely drown out the effect, making the canvas look simply ultramarine blue; in total darkness, the fact that the paint casts its own light can spoil the effect by being too strongly evident. Consider displaying it in a darkened corner or darkened room, or waiting well past sunset and showing it outdoors.

This brings me to my hypothesis on why this effect works at all. I think the effect’s basis is essentially threefold. First, the ultramarine pigment absorbs and scatters the blue light that the Blue Lit gives off, such that the light produced is on net roughly the same color as the ultramarine. Second, the light produced is faint enough that human visual perception tends not to expect it to be emitting light at all, especially if the color is displayed under broadly appropriate lighting conditions; the effect is to make the blue simply look more saturated. And finally, the human visual system’s native white-balancing amplifies that effect, allowing most people to see the paint as an impossibly saturated blue. It seems possible that kaolin improves this effect through additional light scattering; unfortunately, none of this hypothesis helps explain why pressing on the dried paint itself can sometimes cause it to glow.

As a final note, blue isn’t the only hue that this process can make hyperbolic paint for in this way. Stuart Semple’s site offers (as of August 2025) phosphorescent powders in pink, yellow, green, blue, and what purports to be ultraviolet, though I’m not as sure of that last one. All of these work in roughly the same way, and the same general approach and recipe should work with them - just swap out the ultramarine for another intense pigment of the appropriate color. I haven’t tested them myself apart from the green, with which I made a lovely hyperbolic chlorophyll green paint at the same event as the blue; it’s worth noting that different glow pigments glow with different intensities, which you’ll need to calibrate. I recommend also keeping in mind the distinction between additive and subtractive pigments, if you ever want to achieve other colors.


22222/32768