I cannot find suppliers for large volumes of fountain pen ink.

Perhaps I do not have the correct search terms?

I would like to buy fountain pen ink in bulk (1 gallons, 3,785 ml) not little 3 fluid ounce bottles (88-90 ml) at a time.

Yes, I found and bought a 350 ml bottle from Pilot. But that is smaller than the size I want to buy.

I have tested small amounts (400 ml) of DIY ink on cheap Chinese pens, I have developed a formulation of my own using bulk inkjet printer ink as an initial base.

See color mix for navy blue ink

See additives to adjust the flow rate

I checked with a dye manufacturer to see what options are available there, but they do not sell to individuals, only to companies.

I don’t really want to form an LLC to buy ink dye. Hmmmm.