The primary method to separate pen ink, particularly to see its component colors, is through paper chromatography.
Here's a breakdown of the process based on the reference video:
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Apply the Ink: Draw a thick line of the pen ink on a piece of absorbent paper (like filter paper or coffee filter). It's best to go over the same spot repeatedly to concentrate the ink. The line shouldn't be more than 2 millimeters in diameter, according to the video.
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Prepare the Solvent: Fill a jar or glass with a small amount of a suitable solvent. Water often works, but rubbing alcohol (isopropyl alcohol) can also be used. The solvent should be deep enough to touch the bottom of the paper but not touch the ink line directly.
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Run the Chromatography: Suspend the paper in the jar so that the bottom edge (below the ink line) is immersed in the solvent. The solvent will travel up the paper via capillary action.
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Observe Separation: As the solvent moves, it carries the different color pigments in the ink with it. Different pigments will travel at different speeds based on their solubility in the solvent and their affinity for the paper. This separates the ink into its constituent colors.
Why this works: Pen ink is often a mixture of different colored dyes. Chromatography separates these dyes based on their properties. Some dyes are more soluble in the solvent and/or less attracted to the paper, so they travel further up the paper. Others are less soluble or more attracted to the paper, so they don't travel as far. This creates distinct bands of color.
Tips for Success:
- Use a solvent that will dissolve the ink. Water works well for water-based inks. Rubbing alcohol can be used for some inks, particularly those containing alcohol-soluble dyes.
- Ensure the ink line is above the solvent level to start. If the ink dissolves directly into the solvent pool, you won't get good separation.
- Be patient. The process can take some time (minutes to hours) depending on the ink, solvent, and paper.
- Experiment with different inks and solvents for varying results.
