3D Puff — stitching over foam

What is 3D Puff?

A strip of embroidery foam is laid on the garment, the design is stitched over it, and the foam that isn’t covered by thread is torn away afterwards. What stays is a raised, domed letter or shape — the effect you know from cap fronts and varsity jackets.

The foam does nothing on its own. Everything depends on the stitching: it has to be dense enough to hide the foam, wide enough for the foam to rise inside, and — the part most people miss — it has to perforate the foam along the outline so the excess breaks off cleanly instead of stretching and fraying.

Why is it a “section” and not a checkbox on the object?

Because one piece of foam is one piece of foam. Its density, its placement outline, its machine stop and its tack run belong to the whole group of columns sitting on it, not to any single one of them. In StitchPencil that group is a puff section — a layer group with its own inspector — and everything the foam needs is decided there once.

How do I make one?

Draw your satin columns, then either:

group them first — select the rows, Group, then Convert → 3D Puff on the group, or
select them all directly and use Convert → 3D Puff.

Several columns at once is the normal case, not the exception: an F is three strokes, an i is a stem and a dot. They become one section either way. If the columns are already a joined group, the section inherits that.

Only satin qualifies. A fill cannot puff — the foam needs a column with two edges to rise between, and a tatami surface has no such edges.

What does the machine actually do?

The section sews four things, in this order:

The placement outline. A single running stitch around the shape, on bare fabric. This is the guide you lay the foam over — you can see exactly where it belongs.
A stop. The machine pauses. You lay the foam on (a strip roughly half an inch bigger than the design, taped or sprayed down) and start it again.
The tack run. A short, dense bean stitch exactly on the outline. This is the perforation, and it is the single most important step for a clean result. It also holds the foam down before any column starts.
The columns, sewn over the foam at foam density.

You can switch the outline, the stop and the tack run off individually — they appear as their own rows inside the group in the layer list, so you can see when each of them happens. Switch off the tack run if you work with spray adhesive, but know that you are switching off the perforation with it.

Why does an open end need a cap?

Take a column that just stops in mid-air. The cover stitches run across it, side to side — but nothing runs along its end. There is no line of needle holes there, so the foam under the tip has nothing to tear along: it stays attached, and it pokes out from under the thread as a visible fluff of foam.

A cap is a short bar of satin sewn across the end. It does two things: it holds the foam edge in, and it carries the tear line around the corner so the excess breaks off along the outline instead of stopping dead at the tip.

What can I choose at an end?

Tap an end mark on the canvas, or use the list in the section inspector. Five answers:

End cap — the trade’s bar. It reaches a little past the column on each side, which is exactly why it works: the safety margin means no loose stitches hang over the foam edge. The side effect is that it reads as a serif, which can make a handwritten letter look like Times New Roman.
Rounded — the last half-width of the column closes off inside its own width. Nothing sticks out. It looks the way you drew it; it gives up the bar’s safety margin, so a stubborn scrap of foam can survive at the very tip.
Tapered — the column runs out over about two widths to a rounded point. This is the trade’s own alternative to the bar, and the natural choice for script and brush lettering.
Open — no cap at all, deliberately. Right where you want the foam edge to show, or where you know something else covers it.
Manual — see below.

Rounded and tapered shape the geometry, not just the cover: the placement outline and the tack run follow the new shape, so the tear line closes with it. That matters. A tapered cover over a square tear line would leave foam corners that nothing can tear off.

Whatever you pick, the design check keeps asking until every open end has an answer. That is deliberate: an undecided end is the one that goes wrong at the machine.

What happens if I make a puff column wider than that?

Nothing stops you — the export stays open at any width. But two things happen, and the design check names both.

Over 8 mm the cover starts floating over the dome instead of gripping it. Add the pull compensation a foam cover needs on top of your width, and the thread has further to travel than the foam is holding.

Past a certain width it stops being a matter of taste. What has to fit in one throw is the STITCH, and a foam cover’s pull compensation is sewn on top of the width — so the column throws a longer stitch than it is wide. No machine format carries one much longer than about 12 mm in a throw, so StitchPencil splits it, and the extra penetrations land in the middle of the column. On flat satin that is invisible and correct. On foam it is a row of needle holes straight down the crown of the dome: the puff comes out pressed flat exactly where it should be highest, and no amount of tension or stabilizer fixes it afterwards.

The design check names the exact place and how far it runs — “reaches 11.8 mm over 4.1 mm”. Tap the finding and the canvas frames it with an amber ring, so you know which node to narrow.

It only counts stretches long enough to matter. The taper every stroke ends with is not a finding, and neither is an end you built by hand — that decision is already in the section, and the check respects it.

The fix is to narrow the column, or to draw it as two columns side by side with their own domes.

What about the places where two columns meet?

They are not ends. An F has six column ends but only three that face the air — the other three are joints: the top bar runs into the stem, the middle bar butts into its side.

StitchPencil finds those by itself and treats them accordingly:

No cap is sewn there, and you are not asked about them.
A small overshoot a hand-drawn stroke made past the corner is trimmed back so the tip stops just under its neighbour’s cover. Past that it is taken as a shape you meant to draw: a stem drawn deliberately through and beyond its bowl stays exactly as long as you drew it.
The sew order is set so the column that ends into another goes first — the covering column comes down on top afterwards and buries the seam.

Joints are marked on the canvas with a small chain glyph and listed in the section inspector, so you can see that they were recognised.

Why is there a width band instead of one width?

Foam needs about 6 mm of column to rise inside. Below that it’s a dense rope, not a dome. But if the app simply set every column to 6 mm, a stroke drawn with Pencil pressure would lose the thing that made it worth drawing.

So the section has a band — 6 mm at the thin end, 10 mm at the thick end by default. A drawn column is fitted into it and keeps its own swell. The 10 is not a matter of taste: no format carries a stitch longer than about 12 mm in one throw, and over foam one throw is all you want, and the foam cover needs its pull compensation on top of that, and past a certain width the cover starts to float over the dome instead of gripping it.

Watch out when you scale a finished section — the widths scale with it, and a letter shrunk to fit the hoop can quietly leave the band. StitchPencil says so when it happens; nudge the band sliders to refit.

What does the section decide for me?

On foam, four settings move from the object to the section, and the object’s satin panel stops showing them:

Cover density — set for you on foam, denser than an ordinary satin. Denser than ordinary satin, because the cover has to hide the foam and perforate it.
End caps — per end, as above.
Underlay — off. Underlay’s whole job is to compact the fabric before the cover; under foam it just crushes the dome.
Short stitches — off. On fabric they keep thread from stacking on the inside of a curve; on foam they dig a line of holes exactly where the dome should stay whole.

Pull compensation stays yours, but never goes below a floor on foam — the cover has to reach around the dome instead of sitting on top of it. A higher value wins.

What is the manual mode for?

Sometimes you want to build an end yourself: a shape the three presets don’t cover, a decorative cap, a tapered end with a specific angle. Set that end to Manual and the app takes its hands off — nothing is sewn there, nothing is asked about it, and the design check stays quiet.

You then draw your own satin and put it in the section. It is a full member from that moment: it sits on the same foam, it is included in the placement outline and the tack run, its own ends take part in the joint detection, and it takes its place in the sew order. Everything in the section is on the foam — that is the rule that makes this predictable.

The end mark on the canvas turns into a pencil glyph, so a month later you can still see which ends you took over.

What does the design check say about a puff section?

Open ends with no decision — how many of them, until you’ve answered each one.
Column too narrow. Between 4 and 6 mm is the cord zone: it sews, but it comes out as a dense rope rather than a dome.
Column too wide — wide enough that the cover starts to float over the dome instead of gripping it, and the pull compensation pushes the stitch past what the machine sews in one zigzag.
Covers crossing — two columns overlapping away from their ends. The foam is pressed flat there and the tear line is interrupted. Joints are not reported: a meeting by design is not a defect.

Converting back

While anything sits on foam, Convert offers exactly one thing: the way back off it. Under the heading Satin (off the foam) you pick which satin preset the columns should return to — the presets are right there, no submenu.

A satin area can go on foam too, and it needs no end decision at all: its two tips close the foam by themselves, so no bar is sewn there.

Run and Fill are deliberately not offered there. They would leave the objects inside the section: the placement outline only counts satin columns, so the foam would be laid out for a shape that is no longer outlined, while the object keeps sewing at foam density with no tear line around it. The route to a fill still exists, it is just honest — take the column off the foam first, then convert it with the ordinary menu.

The width comes back relatively: the column keeps whatever dynamic it has and only its thinnest place is rebased — on the width it was originally drawn at, which the section remembers, or on the preset’s width when it doesn’t.

Density and underlay come from the preset you picked, not from the foam values — otherwise a flat column would be left sewing at twice the density it needs.

Practical notes for the machine

These are not app settings, but they decide whether the result is clean:

Foam colour close to the thread colour. Never a contrasting one. Whatever the cover does, tiny specks show at the rim and at the tips — matching foam makes them invisible.
2 or 3 mm foam for most work. Thicker gives more height and less forgiveness.
Slow down — around 500 stitches per minute is the usual advice, with slightly tighter top and bobbin tension.
Tear the excess away by hand, then go over the piece with a heat gun on its lowest setting or a hot hairdryer. That shrinks back the last fibres at the tips — the step that makes the difference between “good” and “clean”.
Not for laundry-heavy garments. Foam does not enjoy repeated hot washing, tumble drying or dry cleaning. Caps, jackets and bags are its natural home.
Stitch everything that is not puff first. The foam goes on last, over finished flat embroidery.