Glow Ink

Despite my lack of darkvision, I found navigating through the Underdark less difficult than I initially thought. Aside from the bioluminescent mushroom lamps, it appears all the various signs are written in an ink made of a similar, if not the same, material. Many streets are even lined with this paint as well. I'll have to ask the locals more about it.

— Birki Kroon's travel blog.

This glow in the dark ink is primarily used within the Underdark. Some people adopted it for use in other cave systems on the surface. Its main use is for text on signs and buildings. Over time, pathways were lined with it for easy visibility as well.

How it's Made

Creating this ink is a relatively simple process. The cultures that populated the new Underdark brought over similar methods and adopted them to fit their new environment. It is created in a clean environment to prevent contamination that would ruin the ink. To produce a batch, the following steps must be followed:

Grind the needed mushrooms into a fine powder; if the granules are too large the ink will turn grainy when dried and will be ruined.
Put the powder into a bowl and add distilled water before mixing thoroughly for 30 minutes.
Pour this mixture into the final packaging along with the preserving agent in a 1 : 1/2 ratio. Each container must be shook well for 10 minutes to combine the two.

There are still a few producers who make their batches by hand. In recent years the process was automized via the help of grinding, mixing, and bottling machines.

Type

Writing and art material

Year Created

(To be figured out; sometime after people started inhabiting the underground)

Rarity

Common

Price

2 SP per ounce

Toxicity

Safe to touch and only safe to ingest by Underdark natives

Components

Ingredients

Distilled water
The powder of ground up glow mushrooms
Preserving agent to prevent fading of the glow effect

Do Not Ingest

Although considered safe overall, it is highly advised not to consume the ink for any reason. Most natives to the Underdark experience no effects as the mushrooms used are part of their diet and found in specialty dishes. Anyone not accustomed to the fungus will experience painful digestive symptoms and should seek medical help soon after consumption.

Plot Hooks
Someone or something has been ruining the mushroom farms used to make the ink.
An important person was poisoned; it appears that this ink was used in some discrete fashion.