In article ,
Jeff Liebermann wrote:

To make a slow dry ink, I would guess that the ink should be high
viscosity so that it doesn't drip or run. It should also be high
surface tension to slow evaporation. The high surface tension is easy
enough by adding a few drops of a wetting agent such as Kodak Photo
Flo 200:
https://www.bhphotovideo.com/c/product/28195-REG/Kodak_1464510_Photo_Flo_200_Solution.html

As I recall (and as that page states), Photo Flo is a surfactant,
which _reduces_ the surface tension of the water. This makes it
easier for the water to "wet" the surfaces to which it's applied. The
water spreads out more quickly and (as the page says) "promote[s]
faster, more uniform drying."

Probably not what you want, if you want ink to stay liquid.