Material Notes
Use controlled trials instead of changing several tools at once.
Nib flexibility
Compare two nibs using the same short stroke pattern and record the pressure needed for similar width.
Paper surface
Repeat the same movement on two surfaces and note drag, feathering and hairline consistency.
Ink flow
Observe pooling, drying and the usable length of one dip while keeping movement and nib unchanged.
Practice log
Record the material combination, visible symptom, variable changed and what happened after the change.