Embroidery lettering: satin vs fill, what size each works at, and how the columns are built

Lettering is most of what a small embroidery business sews: names on shirts, team names on caps, monograms on towels. It is also the least forgiving thing to digitise, because letters are small, strokes are narrow, and everyone can tell when an "e" is wrong. This guide explains the two ways to stitch a letter, when each one works, and what the lettering tool does inside a stroke.

Satin: columns across the stroke

A satin letter is built from columns. For each stroke of the letter, the needle zigzags from one edge to the other, advancing about 0.2 mm per stitch, so the thread lies across the stroke in parallel lines 0.4 mm apart on each side. That is the same density commercial designs use. Satin looks raised and glossy because the thread lies in long parallel lengths on top of the fabric, and it is what people mean by "embroidered lettering".

To build the columns, the tool needs the stroke's centre line. It finds it from the letter's outline: the shape is rasterised, thinned to a one-pixel skeleton, and the skeleton is traced into branches, one per stroke, with junctions where strokes meet. Along each branch, a column is placed every 0.2 mm, perpendicular to the branch, reaching the outline on both sides. At junctions (the crossbar of an A, the bowl meeting the stem of an a) the columns of the two strokes overlap slightly; at free ends the last column reaches the tip.

Two things run under the satin. A centre-run underlay, a running stitch along the branch at 2.5 mm, anchors the fabric and holds the column's width; without it satin on a knit sinks and narrows. Pull compensation widens each column by 0.15 mm on each side, the amount 40-weight thread pulls in on stable fabric. Each column starts and ends with a tie of two 0.7 mm stitches so it does not pull out.

Satin works from about 5 mm to 25 mm cap height. The limits are the stroke width, not the letter height:

| Stroke width | Result | |---|---| | under 1.2 mm | Column narrower than three thread widths; looks like a running stitch, shreds on knits | | 1.2–5 mm | Satin's range | | 5–7 mm | Works on stable fabric; snags on anything that rubs | | over 7 mm | Sinks, snags, shows the comb; use a fill |

The tool measures every stroke and warns under 1.2 mm; strokes over 5.5 mm are switched to a fill with a satin edge automatically.

Fill: rows across the letter

A fill letter is stitched as tatami: parallel rows 0.4 mm apart, stitches 3.5 mm long, with the stitch positions staggered row to row so the needle penetrations do not line up into a visible grid. An edge-walk underlay, a running stitch 0.6 mm inside the outline, is stitched first. Fill looks flat and textured rather than glossy; the surface is the row direction, usually 45°.

Fill has no lower stroke-width limit in the sense satin has, but it has a size limit of its own: under about 12 mm cap height a fill letter's rows are too few to read as a fill and the letter becomes a dense blob. Fill is for large lettering: jacket backs, banners, towels.

Fill with a satin edge is the compromise most shops use for anything over 15 mm: a tatami interior with a 1.6 mm satin border centred on the outline. The border gives the raised edge and hides the fill's ragged boundary. The tool offers it as a style, and uses it as the fallback for satin strokes that are too wide.

Outline and running stitch

Satin outline stitches only the 1.6 mm border, leaving the letter open. It is a style in its own right for large lettering and a way to letter thin fonts that would not fill well. Running stitch follows the outline with a single 2.2 mm stitch, or a bean stitch (three passes) for a heavier line. It is the fastest to sew and the only option for very small text, where anything else shreds.

Sizes to avoid

The bad range is 8 to 12 mm in a font with thin strokes: too small for a fill, and satin strokes come out under 1.2 mm. Choose a rounder, heavier font (Fredoka, Baloo, Sniglet in the bundled set) at that size, or go to 12 mm. Script fonts with hairlines (Great Vibes) need 18 mm or more; connected scripts should be lettered with overlaps merged so the joins are stitched once.

The font size guide tabulates minimum sizes per bundled font.

Checking the result

Run the generated file through the pre-flight check. A satin word should show no short stitches, a longest stitch equal to the widest stroke plus compensation, and density around 2 to 3 per square millimetre on the rails with a little more at junctions. A fill word shows density around 1 in the interior and 2 to 3 on the edge if it has a satin border.

Names and lists

For a run of names in the same style the settings are set once and the names change. Batch names generates one file per name from a list or CSV, each centred on the origin, with a colour sheet, so a team order is a single job. Batch names for shops covers the workflow, including checking the longest name against the placement.