Luminous Ink
Luminous inks are inks that glow when exposed to Aura. They come in two variations: blue inks, which glow when exposed to Lunar Aura, and red inks, which glow when exposed to Solar Aura.
The production and use of Luminous inks dates back to before the Darkness on both continents. Luminous inks are more durable and vibrant than Luminous dyes, but have more limited applications.
Properties
Life & Expiration
Over time, the brightness and vibrancy of the ink's glowing effect will diminish. Cheaper inks degrade faster. The material the ink is applied to will affect its rate of decay, and using a protective coating will slow it.
History & Usage
History
The origins of most Luminous inks are murky; many details have been lost to the Darkness. Cultures across both continents have invented various versions of Blue and Red inks with locally sourced materials. As societies connected via trade, ink recipes changed and merged until their origins were forgotten.
Everyday use
Glowing Markers
Blue inks are a popular choice for outdoor signage, since they will glow at night. Red inks can be used in the same way, but on a time limit. After the suns set, the inks will continue to glow for up to two hours. Businesses may use Red inks to indicate when they are open, closing up shop when the sign has completely faded.
Both colors of ink are used to indicate the presence of Aura. This is useful for Auratech debugging and development.
Invisible Inks
When used on the right material, some Luminous inks can be invisible when dormant. This makes them an ideal choice for secret messages. The recipient must only apply a small amount of Glow to the note for the message to appear. A downside to messages hidden in this way is that they can easily be revealed if the message is exposed to the sky at the right time. They also limit the type of person that can read them; a human can only activate Blue inks, and a lilthian can only activate Red.
Art

The ethereal glow of Luminous pigments is hard for an artist to resist, despite the limited color palette. Luminous paints can be used as an accent alongside traditional paints, or alone in a monochromatic style. Sometimes both Red and Blue inks are combined to create an art piece that looks different depending on what type of Aura is present.
Muralists love to use Luminous paints to bring their pieces to life when the suns go down. Sculptors use them for the same purpose, creating figures with glowing eyes or accessories. Sometimes the glow will reveal a hidden message or meaning in the piece.
Tattoos
Some inks--typically those with an organic base--are used in tattooing. Tattoos made from Luminous ink will often be translucent or invisible in normal light. They often accompany black tattoos, as an accent. They glow faintly when exposed to the sky, but are most vibrant when the tattooed individual uses their own powers.
Glowing tattoos are often strategically placed near nexus nodes, ensuring the brightest and most vibrant glow when activated. A skilled tattoo artist will have spent years studying the anatomy of the nexus in order to hone their craft.
Glowing tattoos have a limited lifespan. Depending on the quality of ink and artist, they can last anywhere from five to fifteen years before they stop glowing. For many, this is plenty of time. Others will have their tattoos reinvigorated every few years so that they never stop glowing bright.
Luminous tattoos have great cultural significance in many societies. Humans are known for their intricate tattooing customs.
Distribution
Trade & Market
Completed inks and raw pigments are bought and sold across Auzera and Sanoris. Prices are moderate to high, depending on the quality of the pigment and the distance from its origin.
The cheapest and most common inks are made from kaalite compounds. They can be made anywhere and by almost anyone, but lack vibrancy, brightness, and longevity.
Stelettia ink is the most vibrant and most valuable of Blue inks. The secret to the composition of stelettia pigments is closely guarded. As a consequence, raw pigments are near-impossible to find south of the Divide. Its vibrant blue glow is associated with opulence and quality. Many pigment-makers have attempted to replicate it with cheaper materials, but so far none can match the beauty of true stelettia inks.
The most valuable Red ink is made from the shells of khocelia beetles, an insect native to Southern Auzera. While pricey--especially north of the Divide--it still cannot match Stelettia Blue in value. Where Khocelia Red does excel, however, is in its dormant state. Khocelia Red is opaque and vibrant even when it isn't glowing, making it a favored pigment for painters.
Storage
To preserve the integrity of the glowing effect, inks must be stored in a location where they will not be exposed to the sky. Inks made with organic material should be kept somewhere cool, dry, and dark, to avoid mold or bacteria growth. The best places to store inks are underground cellars or insulated sheds with no windows.


Oh I really like that. Can I order some inks?
Here are my Entries for the water continent Ulűri̋qi̋
Your local librarian or scribe may have some khaalite-based inks for you to purchase, but if you are interested in Stelettia or Khocelia colors then you'll have to track down a more specialized trader. They don't like to send such expensive inks in the mail!