Calfonts: honing letters from rough sketches to clean curves

Honing is the part of font design between “I have a sketch” and “I have a glyph that ships.” The Calfonts honing tutorial — adapted here — covers the boring, decisive 80% of drawing: fixing paths automatically where you can, fixing them by hand where you must.

Step 1: automatic path fixing

FontLab’s automatic tools resolve a surprising amount of contour mess:

• Optimize contours removes superfluous points without changing the shape.
• Convert to TrueType / PostScript rewrites curves in the target curve type cleanly.
• Reverse path direction fixes paths whose winding is wrong (outer counterclockwise, inner clockwise — or the reverse, depending on PostScript vs TrueType).
• Heal openings and overlaps fixes contours that have been broken by editing.

Run these first. They are fast, conservative, and remove the kind of contour debris that makes hand-fixing harder than it needs to be.

Step 2: fixing paths by hand

What automation can’t fix:

• Visual proportions. A counter that is too small. A bowl that is asymmetric in a way the design does not justify. The shoulder of n that meets the stem at a wrong angle.
• Curve quality. Inflection points where there shouldn’t be any. Bézier handles that don’t align with the curve direction at on-curve points (which produces a small but visible kink).
• Spurious points. Two on-curve points where one would do. Three points where two would do. The rule: if removing a point doesn’t change the shape, remove it.

The Calfonts heuristic is to look at every glyph at three sizes: the size you are designing at (large), the intended use size (small), and a deliberately-too-large size (200pt+). Different problems show at different sizes.

Step 3: curve types and tension

The Calfonts material spends real time on curve tension — the question of how full or how empty a curve looks at a given handle length. A 50% handle (the so-called “circle” tension) makes a curve that looks like part of a circle. Shorter handles produce flatter, more rectangular curves. Longer handles produce ballooning curves that often look wrong.

Most letterforms want handles in the 55–65% range. Going outside that range is a deliberate design choice; getting there by accident is a bug.

Step 4: optical adjustment

Curved letters need to overshoot straight ones — o extends slightly above and below n. Diagonals (v, w, y) usually overshoot more than rounds. These adjustments are tiny in number (1–2% of UPM) and enormous in effect. The Calfonts tutorial recommends setting overshoot zones in FontLab so that the values apply consistently across glyphs rather than being eyeballed per glyph.

When honing is done

You stop honing when you cannot identify a specific change that would make the glyph better. That is not “when you are tired of it” or “when the deadline arrives” — though both happen. The Calfonts standard is the higher one.

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