First of all, I really like Noodlers Ink (www.noodlersink.com). This do-it-yourself (DIY) ink experiment is out of curiosity, not dissatisfaction with their ink.

Due to competitive issues, no one shares fountain pen ink formulations online. I thought there might be an open-source formulation, but inks are not like software code. The patent filings are all for ink-jet ink formulations, and they are vague enough to not give the precise mixes. So an experiment was in order.

After researching fountain pen ink, I found that the ingredients are:

For mold prevention, various studies have shown that vinegar solution kills up to 85 percent of mold spores as well as bacteria and viruses.^[1]

I chose to use a greener substitute glycol, vegetable glycerin. Glycerin is a non-toxic fluid made from plant oils in its natural form.^[2] Glycerin is commonly used as a humectant (meaning it preserves moisture), solvent, and preservative. Glycerin is also an emollient, which means that it has the quality to soothe and soften the skin, which makes this extremely popular for soap making.^[2]

ASTM International recently announced standards for Glycerin use because it is seen as a much more environmental friendly and cost-effective alternative than Ethylene Glycol.^[3] Glycerin, which is nontoxic to the environment, was eventually replaced by Ethylene Glycol in the 1930’s due to cost considerations.^[3] Close to neutral on a corrosive scale.^[3]

After realizing that water makes the recipe thinner, I wanted a way to thicken the ink somewhat. My base inks, ink-jet printer ink, are formulated differently than fountain pen ink. I have found ink-jet printer ink is too runny or "wet". That is a technical term that means the viscosity is too low.

I started by defining, for me, good looks like:

So I devised an low cost experiment. I had purchased some $8-9 pens from China and did not mind if they were ruined. My plan was to vary the mix of glycerin to ink-jet ink.

I already knew that the current ink-jet formulation was not viscous enough for fountain pens (flows too fast from the nib, resulting in feathering and bleed-through).

I tested each batch in the converter. I figured worst case, I might have to buy some more converters. As it turns out, there was no impact to the converters, which I suspected.

I researched extensively but found many varying opinions, many with no data to support them.

I still had ink in jars from my last efforts to mix colors that I wanted, so I chose to use those as the ink-jet inks to test.

I went to the pharmacy and asked for glycerin, but the pharmacist said they used to carry it, but low sales resulted in not carrying it anymore. So I ordered a 118 ml (4 fl oz) bottle from Amazon. It was pure vegetable glycerin, food grade.

When I tried sucking the glycerin into the ink syringe (normally used as a way to refill some converters) the undiluted glycerin was too thick and I only got a little. So I moved to a larger diameter ink syringe. This worked well enough to get enough in to measure in milliliters.

I started with a drop, but found no difference.

After increasing the mix of glycerin it started to show a difference.

For me, I got to a viscosity that works on all 8 of my fountain pens (both the cheap ones (more) and the couple of more expensive ones) when I got to about a 40% mix of glycerin to ink.

It worked so well that I added glycerin to all my batches of ink in their various colors. Now I can use the ink-jet ink in the colors I want and at the flow rate I want.

November 3, 2019 - Follow-up.

The ink does not form a crust on the nib. Success. I may want even more glycerin to slow the flow further. I will use this batch of DIY ink first and we’ll see if I want to experiment on this more.