Recipe for a Biodegradable Blue Ink for Fountain Pens and Dip Pens

I, like many other people, make an effort to move away from disposable stationary, which are wasteful. I wanted to formulate a fountain pen ink based on the sustainable food dye blue spirulina (also known as phycocyanin). This ink has many interesting properties: it is biodegradable, non-toxic (except if you drink large quantities of it!) and quite cheap to make.

It is worth mentioning that the ink performs very well with the Muji fountain pen on cheap 20 lb printer paper, with minimal feathering being observed, although you would need to use 28 lb paper should you like to write double-sided. Additionally, you may be interested in crafting your own notebooks and perform Optical Character Recognition (OCR) on your handwritten pages with ScriptReader! Check out my github repos for PrintANotebook and Scriptreader for more details.

I did a stability test, and the ink formulation with 32 weight percent of glycerine was stable for up to a year at ambient temperature (20-28 degrees Celsius, see the photo above and the PDF report below). As a note of caution, please keep in mind that this ink is not of archival quality and should therefore not be used for official purposes.

Supplies

Equipment:

- A centigram scale (0.01 g), two spoons and two weighing papers for weighing out the sodium ascorbate and phycocyanin.

- Two small plastic container for weighing out the distilled water and glycerine. They need to be light enough to use on your scale, yet able to contain around 30 mL (or 1 fl. oz.) just to be on the safe side.

- An eyedropper pipette for weighing out the appropriate amount of distilled water.

- A 1 mL syringe (without the needle) to measure out and dispense the benzyl alcohol preservative.

- A blue or amber glass jar to pour your ink into, the color of the vial will shield the ink from light, as phycocyanin is somewhat light-sensitive.

Materials:

- 14.48 g of distilled or deionized water (solvent, the ink is water-based and using distilled or deionized water will help prolong the ink’s shelf-life)

- 8.96 g of glycerine (32% wt/wt of glycerine is used as a humectant and thickening agent to give the ink a slicker feel. It also stabilizes the blue color in the ink, giving it a longer shelf life)

- 0.28 mL of benzyl alcohol (preservative, mould inhibitor used at around 1 % wt/wt concentration in the final mixture)

- 0.28 g of sodium ascorbate (sodium salt of vitamin C, used as an antioxidant at a concentration of around 1% wt/wt to stabilize the phycocyanin blue pigment towards light and oxidation)

- 4.00 g of phycocyanin powder (Also known as blue spirulina extract, a blue-colored protein that acts as the dye for this ink)

- 1 drop of polysorbate 80 (Also known as Tween 80, a non-ionic surfactant that will reduce the surface tension of the aqueous ink, thereby improving its flow properties)

Step 1: Weigh Out the Water

Weigh out 14.48 g of distilled water in a small plastic container.

Step 2: Weigh Out the Glycerine

Weigh out 8.96 g of glycerine in another plastic container.

Step 3: Add the Water to the Glycerine

Step 4: Add Benzyl Alcohol

With a 1 mL plastic syringe, draw 0.28 mL of benzyl alcohol (mold inhibitor), add it to the mixture from step 3 and stir well.

Step 5: Weigh Out the Sodium Ascorbate

Weigh out 0.28 g of sodium ascorbate (antioxidant) and add it to the mixture and stir well.

Step 6: Weigh Out the Phycocyanin

Weigh out 4.00 g of phycocyanin (also known as blue algae extract, the dye used in this ink recipe) and add it to the mortar.

Step 7: Add Glycerine Solution to the Phycocyanin

Add the glycerine solution to the mortar containing the phycocyanin and mix thoroughly using the pestle to ensure complete dissolution.

Step 8: Add a Drop of Polysorbate 80

The addition of a surfactant will help with the flow properties of the ink. Add a drop of the non-ionic surfactant polysorbate 80 (also known as Tween 80) to the mortar and mix well with the pestle. It’s really important to only add a single small drop, as adding too much surfactant could result in the ink being too runny.

Step 9: (optional) Filter Through Number 2 Cone Coffee Filter

This step is optional, as all the constituents are soluble in water (there can however be some gummy phycocyanin residue, but this adheres to the mortar and pestle and does not make its way into your ink container upon transferring the ink). Filter the ink through a number 2 cone coffee filter into the glass ink container. You will likely need to raise the filter paper to allow good flow into the glass jar. You may also lightly squeeze the filter paper to increase the flow if the filtration is too sluggish, but be careful to handle the filter paper very delicately, so as not to rip it.