I would not choose plant ink for maximum lightfastness unless the plant source is making a tannin-heavy brown, a walnut-style dark earth tone, or an iron-modified botanical ink. If your question is literally which plants make the most lightfast ink colors, the short list is walnut hulls, oak galls used with iron, strong tea or bark tannins darkened with iron, and a few dense berry or leaf extracts only when you accept that they are usually less stable than they first appear on the page.
That is the part beginners usually miss: a color can look rich, lubricated, and beautifully shaded in a fountain pen, then fade badly in a sunny room or even in a bright notebook left open for a month. I test inks like a product designer, not like a romantic forager. I care about line clarity, dry time, cleaning risk, paper behavior, and whether the color still makes sense after real use. For home experiments, plant inks can be fun, but if permanence matters more than novelty, you want the plant material that produces dark tannins, not the prettiest fresh color in the pot.
The Short Answer
The most lightfast plant-based ink colors are usually the least flashy ones: dark browns, sepia browns, charcoal-browns, and near-black tones made from high-tannin plant material. Walnut hull ink is the classic example. Oak gall ink is even more durable in practice, although it is really a plant-plus-iron recipe rather than a pure plant dye. Pomegranate rind, tea, sumac, and some bark-based extractions can also hold up reasonably well when formulated toward brown or black instead of bright red, purple, or green.
By contrast, many beginner-friendly botanical colors that look exciting at first, like hibiscus magenta, beet red, pokeberry purple, red cabbage blue-violet, or spinach green, are usually poor choices if you care about lightfastness. I have seen this pattern again and again with homemade colorants: the brighter and more food-like the color looks, the faster it tends to disappoint under light. If you want a reliable writing ink rather than a short-lived art experiment, aim for tannin-rich plants and expect subdued colors.
Why This Matters More Than Most Beginners Think
When people ask whether you can make fountain pen ink at home, they are usually thinking about color and not permanence. The bigger issue is that fountain pens put a liquid dye system onto paper in a very thin layer. That thin layer does not hide weaknesses. A homemade plant ink can seem fine during the first week, then shift, bleach, brown out, or vanish where the page catches daylight.
- Lightfastness affects whether notes remain readable. A sketchbook page can tolerate some fading; a journal, recipe book, or annotation set usually cannot.
- Plant pigments and plant tannins behave differently. Pigments that give fruits and flowers their vivid color are often less stable than the tannins that create duller browns.
- Fountain pen use is less forgiving than dip pen use. A dip pen can handle thicker, sediment-prone mixtures, but a fountain pen demands cleaner, more predictable liquid.
- Ink failure is expensive in time, not just money. The cost of a failed batch is small; the cost of rewriting pages or cleaning a stained pen is not.
My practical verdict is simple: if you are making ink for the experience, almost any plant can teach you something. If you are making ink for actual writing, lightfastness belongs near the top of the checklist. That is why I usually tell beginners to test their homemade colors with cheap tools first, such as a glass dip pen and a small watercolor paper pad, before they put any experimental batch into a fountain pen.
The reason this topic matters is that nib size quietly changes almost everything a beginner notices first: smoothness, control, ink flow, dry time, and how forgiving the pen feels on ordinary paper. People often assume nib width is just a style preference, but in practice it changes the whole learning curve.
I have also found that beginners blame the pen when the real mismatch is width versus paper or width versus handwriting size. A nib that feels expressive to one person can feel messy, slow-drying, or oddly broad to someone who writes smaller or uses cheap office paper every day.
That is why I treat nib size as a practical fit question, not a collector trivia question. The right width makes the pen easier to trust, which is a big deal when you are still deciding whether fountain pens are enjoyable enough to keep using.
What I Look for First
Before I care about hue, I want to know what chemical family is carrying the color and how that will translate to writing performance. With plant inks, that usually means separating tannin-based browns from showy dye-based reds, purples, and greens. If the source plant is famous for tannins, I pay attention. If it is famous for bright edible color, I assume the lightfastness is mediocre until proven otherwise.
- Tannin density. Walnut hulls, oak galls, tea, pomegranate rind, and some barks start ahead because tannins tend to produce more durable brown-black writing tones.
- Final color direction. Brown, sepia, and black-adjacent mixes are usually safer bets than pink, violet, or green if sunlight resistance is the goal.
- Sediment and cleanliness. A lightfast batch is still a bad fountain pen ink if it leaves grit, mold risk, or heavy residue in the feed.
- Paper bonding. Some inks look weak in the bottle but become more convincing once they oxidize or set into paper fibers over a day or two.
If I were ranking plant sources for beginners by realistic permanence, I would put them roughly like this:
| Plant source | Typical color | Lightfastness outlook | Beginner note |
|---|---|---|---|
| Walnut hull | Brown to deep sepia | Good | One of the safest starting points for readable, stable color |
| Oak gall with iron | Gray-black to black | Very good | Excellent permanence, but formulation matters and pen safety needs care |
| Pomegranate rind or strong tea with modifier | Tan to brown | Moderate to good | Useful for experiments, often better than bright flower inks |
| Berry, beet, hibiscus, cabbage | Red, purple, pink, blue-violet | Poor to moderate | Fun color studies, weak long-term writing choice |
One testing observation I trust: walnut-based browns often look boring in a jar and better on paper after a few pages. Another: many berry inks do the opposite. They photograph beautifully on day one, then lose the argument after actual exposure.
How to Choose Without Overbuying
Most beginners do not need a big home-ink lab. You need a tight test loop that tells you whether a plant color is worth pursuing. The smart buy is not more ingredients. It is a few low-risk tools that let you compare batches, see fading clearly, and avoid sacrificing a good pen too early.
- Start with one durable plant family. Walnut hull powder or a tannin-rich botanical source is a better first experiment than collecting six bright flowers.
- Test with a dip pen first. Homemade inks can be acidic, particulate, or biologically unstable, and a dip setup exposes fewer things to damage.
- Run a simple light test. Put one sample in a dark drawer and tape a matching sample in a sunny window for one to two weeks.
- Use inexpensive papers with different absorbency. You want to see feathering, shading, dry time, and whether the color collapses on ordinary notebook stock.
If you want useful gear, I would keep it restrained: a set of amber glass dropper bottles for small batches, coffee filters for ink filtering, and a cheap dip pen before you ever think about converters and piston fillers. My opinionated rule is that if a homemade plant ink has not survived filtration, a week of sitting, and a window fade test, it has not earned a place in a fountain pen.
For readers who still want to try a fountain pen-safe path, the better value move is often buying a known permanent commercial ink and treating homemade plant ink as a side project. A bottle of De Atramentis Document Ink or Platinum Carbon Black gives you a baseline for permanence, flow, and cleaning. That baseline is valuable because it stops you from mistaking novelty for performance.
Common Mistakes and Misconceptions
The biggest misconception is that ?natural? means stable. It does not. Plenty of natural colorants are notoriously fugitive. Flowers and berries evolved to attract pollinators and seed dispersers, not to archive your notebook. Another common mistake is assuming that dark-looking liquid equals durable writing. Some plant brews dry much lighter than expected, and others oxidize into a color that is technically darker but less legible.
The second mistake is putting homemade ink straight into a fountain pen because the first writing sample looked smooth. Fountain pens are fluid systems with narrow channels. Plant sediment, sugar residues, acidity, and microbial growth all matter. I have tested enough pens to say this plainly: a batch can feel acceptable in the nib for one page and still be a poor long-term resident in the feed. If you insist on testing a homemade botanical ink in a fountain pen, use an inexpensive, easy-to-clean model and accept the risk. Better yet, keep homebrew inks for dip pens unless you have filtered, stabilized, and observed the batch carefully.
There is also confusion between colorfastness and water resistance. Oak gall style inks can be quite durable because they chemically darken and bind into paper, but that same chemistry is exactly why formulation discipline matters. Walnut ink can be pleasantly stable for a botanical brown, but it still may not match modern archival inks for water, light, and pH balance all at once. The beginner-friendly takeaway is not that homemade ink is pointless. It is that you should judge each batch on legibility, fade resistance, and pen safety as separate criteria.
Bottom Line
If your goal is the most lightfast plant-made ink colors, stay with tannin-rich sources and expect brown-to-black results, not jewel tones. Walnut hull is the easiest plant answer. Oak gall with iron is the strongest permanence answer, though it demands more caution. Tea, bark, sumac, and pomegranate-type tannin sources can be respectable middle-ground experiments. Bright floral, berry, and vegetable inks are usually better as temporary art colors than dependable writing inks.
My final verdict is blunt because it saves beginners time: make plant ink at home if you want to learn, but do not expect the most vivid homemade colors to be the most durable. In real writing use, the winners are the earthy, tannic, slightly unglamorous inks that stay readable. That may sound less exciting, but in a pen case, boring durability beats pretty failure every time.
If you want the safest beginner answer, I would still lean fine or medium before anything more extreme. Those widths usually give you enough character to enjoy the pen without forcing you to manage every downside at once.
From there, the smartest upgrade path is not buying more expensive immediately. It is noticing whether you want a cleaner line, more expressive ink behavior, less feedback, or more control on cheap paper. Once you know which direction you want to move, choosing the next nib size becomes dramatically easier.