Short answer: A bust dart lies flat when the pattern ends the dart short of the bust point, the last stitches run along the fold instead of stopping across it, the tip is tied off instead of backstitched, and the dart is pressed over a curved ham. Write each of these on the tech pack, then wash the sample before you approve it.
Why does the bust dart point bubble on a woven top or blouse?
A bust dart bubbles at the point when the fabric cannot taper smoothly from the folded dart into the flat bodice. A dart is a folded wedge of cloth. At its point, the fold has to disappear into a single layer of fabric. If the stitching or the pattern makes that change sudden, the extra cloth has nowhere to go, and it forms a small pouch, dimple or “nipple” at the tip.
The sewing references point to five separate causes:
- The stitching line meets the fold at an angle. WeAllSew, the Bernina sewing site, says a straight, untapered seam creates a stress point and causes the “dart dimple” at the tip (WeAllSew).
- The point is backstitched. The Sewing.org dart lesson says not to backstitch at the point “because this may cause puckering” (Sewing.org).
- The thread is knotted or pulled too tight. WeAllSew warns that tugging hard on the threads will pucker the dart tip (WeAllSew). BellaOnline notes that knotted thread ends can leave a tiny bump at the point that you can feel, even when you cannot see it (BellaOnline).
- The dart is too wide or was shortened badly on the pattern. See the pattern section below.
- The thread or the fabric shrinks after sewing. See the washing section below.
How should the dart point be sewn so the blouse lies flat?
The bust dart point lies flat when the last few stitches run along the fold, very close to it, so the stitching line fades into the fold instead of crossing it. The sources agree on this principle and give similar numbers:
- Sewing.org says to change to a shorter stitch when about 1.3 cm remains, and to take the final two or three stitches directly on the fold (Sewing.org).
- Casey’s Clothing Class says the last two or three stitches should be as close to the fold as possible to make a sharp point “without bubbles” (Casey’s Clothing Class).
- WeAllSew shortens the stitch to 1.0 mm at the taper and angles the line so it reaches the fold before the point, then follows the fold to the end (WeAllSew).
The sources disagree on one detail. Sewing.org says to keep stitching off the fabric edge after the last stitches on the fold. WeAllSew says not to sew off the fabric past the fold. Both put the last stitches on the fold. On a tech pack, the safe instruction is the shared one: taper the line so the final stitches run along the fold, with a shorter stitch near the point.
Should the dart point be backstitched, tied off or secured another way?
The dart point should not be backstitched. A backtack puts extra thread and a sharp change of direction exactly where the fold must disappear. The table compares the methods the sources describe.
| Method at the dart point | How it is done | What the source says about the tip |
|---|---|---|
| Backstitch (backtack) at the point | Reverse stitch over the last stitches | May cause puckering; Sewing.org says not to do it (Sewing.org) |
| Tie the thread tails by hand | Leave long tails, tie a knot at the point, trim | Casey’s Clothing Class says do not backstitch and slide the knot close to the point (Casey’s Clothing Class); WeAllSew warns that pulling hard puckers the tip (WeAllSew) |
| Lock stitches in the fold at zero stitch length | Stitch several times in the fold with stitch length set to zero, then clip | Described by Sewing.org as the way to secure the point instead of a backstitch (Sewing.org) |
| Continuous-thread (bobbin-thread) dart | Sew from the point toward the wide end using one continuous thread | No knot, trim or backstitch at the point, so no small bump there; recommended for very sheer fabric (BellaOnline) |
Whichever method is used, the tech pack should say it in words: “no backtack at dart point.” If the sewing machine is set to backtack automatically at the end of a seam, the dart point needs to be excluded from that setting.
Where should the bust dart end on the pattern?
The bust dart should point toward the bust apex but stop short of it. Made by Rae’s worked example is a dart that ended right at the apex and was shortened by about 2.5 cm. The published distances vary with cup size:
- Made by Rae gives about 1.3 to 2.5 cm short of the apex, with the larger distance for a bigger bust (Made by Rae).
- Cashmerette says darts for larger cup sizes should end around 5 cm before the apex (Cashmerette).
- Casey’s Clothing Class says darts end about 2.5 cm from the curve they point to (Casey’s Clothing Class).
Because the right distance depends on the fit model and the size range, a buyer should not copy a number from the internet onto the tech pack. Put the measured dart point to bust point distance for the base size on the spec sheet, and check it on the fit sample. A missing or undersized bust dart is also one cause of armhole gape on close-fitting sleeveless tops, covered in armhole gape on sleeveless tops, dresses and kaftans.
Does dart width and fabric weight change whether the point bubbles?
Yes. A wide bust dart, or a dart in a thick woven fabric, is harder to press flat and more likely to distort. Closet Core Patterns says that as a dart’s angle grows to around 35°, the dart becomes harder to sew and press correctly and the fabric becomes skewed; it suggests dividing one wide dart into two or more narrower ones (Closet Core Patterns).
How the pattern was altered also matters. In a Fashion-Incubator discussion of shortening a dart, one commenter warns that a shortened dart can release too much fabric at its end and pucker, and that two smaller darts might work better (Fashion-Incubator). If a dart was shortened during fitting, ask how the legs were redrawn.
For bulky fabric, Sewing.org says wide darts should be slashed open along the fold, trimmed to about 1.5 cm or less, cut to within about 1.3 cm of the point, and pressed open (Sewing.org). For a heavier woven top, state on the tech pack whether the dart is to be left folded or slashed and pressed open.
How should bust darts be pressed on a woven blouse?
Bust darts should be pressed over a curved surface such as a tailor’s ham, so the shaping is kept and the point is not flattened into a crease. Sewing.org says to press darts over the curve of a ham and to press them before they are crossed by another seam (Sewing.org).
Pressing direction is a convention, and conventions differ. Sewing.org says vertical darts are pressed toward the centre front or centre back and horizontal darts downward (Sewing.org). The Tailoress presses darts toward the side seams (The Tailoress). Since the sources do not agree, write the direction on the tech pack, so every piece in bulk matches the approved sample. A side bust dart is horizontal, so the Sewing.org rule would press it downward.
Can a flat dart point bubble after washing?
Yes. A dart point that looked flat after pressing can pucker after washing if the thread or the fabric shrinks. Coats, the thread maker, says soft cotton thread swells and shortens when wet; the thread may recover when dry, but the fabric can stay puckered. Coats says there is no accurate scientific test for this type of pucker, so it is found by a visual check after washing or finishing, and it recommends synthetic threads with low wet shrinkage (Coats).
Coats also describes tension pucker: sewing with too much thread tension stretches the thread, which relaxes after sewing and gathers the seam. Its test is to cut the top and bottom threads over a short length; if the pucker relaxes, tension was the cause (Coats). For thread and needle choice on the rest of the garment, see matching thread, needle and stitch to the fabric.
What should a buyer put on the tech pack for bust darts?
The tech pack for a woven top or blouse should state the dart geometry, the sewing of the point and the pressing, because each of these can change between sample and bulk.
- Dart position: dart point to bust point distance for the base size, and the grading of that distance.
- Dart intake and length: measured on the pattern; note if a wide dart is divided into two.
- Point finish: “taper the last stitches along the fold; no backtack at dart point; secure by tie-off” or the method agreed.
- Stitch length near the point, if it differs from the main seam.
- Dart treatment for heavier fabric: folded, or slashed and pressed open.
- Pressing: over a ham, with the direction stated.
- Thread: type agreed with the fabric, with low wet shrinkage.
- Wash test: the sample is approved after washing to the care label, not before.
The same logic of stating ease and pressing in writing applies to the sleeve head; see sleeve cap ease on woven tops.
What on the sample tells you the dart points will bubble in bulk?
On the sample, the warning signs are visible at the dart tip on both faces of the blouse. Check these before approval:
- On the right side: a small dome, dimple or point at the tip, seen best in side light on a dress form or fit model.
- On the wrong side: a backtack or a hard knot at the point, or a stitching line that crosses the fold instead of running along it.
- Dart tip too close to the apex: measure dart point to bust point and compare with the spec.
- A wide dart that looks skewed or pulls on one side, which Closet Core Patterns names as a sign the dart is too wide (Closet Core Patterns).
- Pucker that appears only after washing: Coats links this to thread or fabric shrinkage; its cut-thread test separates it from tension pucker (Coats).
Approve the sample only when the dart points are flat after a wash, and keep that washed sample as the reference for bulk inspection.
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