5 things to weigh up on fountain pen mistakes

A pen that misbehaves has three possible causes and people almost always guess the wrong one. It is the pen, the paper, or the hand. A weekend of elimination settles it, costs nothing, and ends either with a working pen or with a precise description you can hand to somebody who can fix it.

What to take away

Eliminate in order: paper, then hand, then pen. The cheapest causes are the most common.
Change one variable at a time and write down what happened.
Your hand is a genuine variable and it changes with fatigue, age and which hand you use.
If Sunday ends with the fault still present, you now have a description worth sending.

Saturday: eliminate the paper and the hand

Morning. Write the same sentence with the suspect pen on three papers: your control pad, a cheap pad, and any coated or glossy sheet. Note which behaves.
Midday. Repeat on the control paper with a different pen you trust. If that pen also misbehaves, the paper is the problem and you are finished.
Afternoon. Pressure test. Write the sentence at your normal pressure, then as lightly as the ink allows. Note whether the fault changes.
Evening. Angle test. Rotate the pen slightly left and right, and raise and lower the writing angle. Record where the fault appears and disappears.

Your hand is not a constant

It is tempting to treat the hand as fixed and the pen as variable. Neither is fixed. Handwriting changes measurably over a lifetime: a machine learning study of handwriting decline with human aging found age-related differences in handwriting that could be detected from the writing itself.

Shorter-term variation is larger than people expect too. Work comparing nondominant and dominant handwriting clarity examined the factors affecting how clear writing is with the unpracticed hand, which is an extreme version of what fatigue and an unfamiliar grip do to anybody.

The practical version: test in the morning and again in the evening. A fault that appears only when you are tired is a grip fault.

Sunday: eliminate the pen

Morning. Flush thoroughly with cool water until it runs clear, then dry and refill with a known ink.
Midday. Write a page. If the fault has gone, it was dried ink or residue, and your maintenance interval is too long.
Afternoon. If it persists, examine the nib under magnification. Look at tine alignment from above and tipping shape from the side.
Evening. Write the description: symptom, conditions where it appears and disappears, what you tried, what changed.

Record it as you go

Use one page, ruled into columns: variable changed, what happened, time of day. Two days of that is a genuine dataset by the standards of this hobby, and it is the thing that prevents you from testing the same combination twice on Sunday because you forgot Saturday's result.

What to do with the result

If the fault survived all of that, do not start bending things. You now have exactly what a repairer needs. Photograph the nib, attach the writing samples, and send the description. The tools that are safe to use yourself, and the two that are not, are covered in maintenance tools. If the diagnosis turned out to be pressure or angle, that is a practice problem rather than a repair, and the weekend practice plan is the right next step.

Common questions

What if the fault disappears during testing? Note the conditions under which it disappeared. Intermittent faults are usually temperature, dry time between sessions, or grip fatigue.

Should I change ink during the diagnosis? Once, on Sunday, after the flush. Changing ink earlier introduces a second variable while you are still eliminating the first.

How do I test tine alignment without a loupe? Hold the nib up to a light and look down the slit. Uneven tines usually show as one tip catching the light differently.

Is it worth doing this for a cheap pen? Yes, once. The diagnosis skill transfers to every pen you own afterward, and it is the difference between owning pens and replacing them.