Im pretty clueless on makimg marker ink. In the years ive been painting ive only bought marker ink and haven't actually made it.
to make ink you basically need ink with solvents, so methylated spirits would work with the cartridges from high lighters for example, or pen ink, etc etc. the wood stain is an old traditional technique that ive personally never tried
wood stain is used as an additive for staining purposes not generally a base solvent, i personally really like to use pvc primer as my solvent, not only is it serious shit but it stains like a mofo and adds a purple hue, if i dont use it i usually use naptha or xylene. If you use just woodstain and spirits it will streak really bad on smooth surfaces and be see through. you would need something else to make it more opaque, using pen sludge may do the trick. Making ink is a big part experimentation. Some things just don't get along. Some will eat through certain plastics, and it sucks when a mop goes soft and busts in your bag or pocket. If you just getting into it, the pen ink method is probably the easist to get down, then you can use different chemical bases and compare say pvc primer to 99% alcohol. (primer wins) There a plethora of knowledge in the early days of both the toy and non toy ink making threads, but youll probably have to go way back, look for me and H3tting3rs posts