Two habits decide whether a quilt top looks crisp: pressing each seam before the next is sewn, and arranging seams so they butt together at each intersection. A block can be cut perfectly and still look sloppy if either is skipped.
Pressing is not ironing
Ironing slides the iron across the cloth, which stretches bias edges and distorts a piece. Pressing lifts the iron and puts it down on one spot. On pieced work, always press: set the iron on the seam, hold a moment, lift, and move on. Stretching is the main reason triangles end up too big and blocks come out wavy.
Steam is a matter of taste. A dry iron gives a firm, flat seam and leaves the fabric unchanged. Steam gives a sharper crease, but it can shrink cotton a little and stretch bias cuts. Many quilters use a spritz of water and a dry iron, which gives a sharp result with less distortion.
Set the seam first
Before opening a seam, press it closed as sewn, with the two fabrics together. This sets the stitches into the fabric and eases any small puckers. Then open the two pieces and press the seam to one side, working from the right side, making sure the fabric folds right at the seam line. Check for a small pleat, which means the piece was pressed before opening or the seam was not flat.
Which way to press
There are two schools.
- To one side, toward the darker fabric. A seam pressed to one side is stronger and does not leave gaps where stitches can show through lighter fabric. Pressing toward the dark fabric stops the dark seam allowance shadowing through a pale piece.
- Open, with the seam allowance split flat. The join is bulk-free, which helps at busy intersections with many seams and gives a flatter top for quilting, but the stitching is more exposed and the seam can be a little weaker.
A common rule: press to one side for blocks made of a few pieces, open where eight or more seams meet, such as the centre of a star.
Planning opposing seams
When two rows of a block are sewn together, press the seams in adjacent rows in opposite directions. Where they meet, each seam allowance pushes against the other, locking them so the two seam lines match and the join sits flat. This is called nesting. You can feel it: the two ridges lock together when you push the pieces together.
For a nine patch, press the top row seams toward the centre, the middle row seams outward and the bottom row seams toward the centre. Every intersection then has seams going opposite ways. For a four patch, press each pair in opposite directions. Write the direction on a sketch before you begin, so you can follow it through the blocks.
Matching points
A point is where several seams meet, such as the centre of a star or the tip of a triangle. To match them:
- Put the two pieces right sides together with the nested seams meeting.
- Push a pin straight down through the seam line of the top piece, at exactly the place where the stitching line crosses.
- Bring the pin out through the seam line of the bottom piece at the same spot. The pin should go through both seams at their crossing.
- Leave the pin in and add pins on each side, then sew slowly and remove pins as the needle reaches them, rather than sewing over them.
- Sew just to the left of the pin position, so the stitching passes through the crossing and not beside it.
A long seam can be marked with pins every 2 to 3 inches so the fabric does not shift. If the two pieces have slightly different lengths, put the longer one on top, since the feed dogs tend to draw up the lower piece and ease the top.
Points that get cut off
If the tip of a triangle vanishes into the seam allowance in the next seam, the stitching line is too close to the edge. Aim to stitch one thread width outside the crossing of the previous seam lines, so the point stays fully visible. It is easier to remove a thread than to restore a point.
Half-square triangles and bias edges
Triangles cut on the diagonal have a bias edge that stretches. Press gently and avoid pulling the triangles after sewing. The half-square triangle guide on this site explains how to make them two at a time and trim to size. The blocks database shows what each traditional block needs, so you can see which ones have many points.
Diagnosing a seam that will not meet
- A point that is off by a small amount on each block: your seam allowance is slightly off, so every seam drifts. Test with a three-strip sample.
- Points that are misaligned on one side only: the top piece was pulled during sewing.
- Points that line up at the edge but not in the middle: the pieces were cut to different lengths.
- Bulky intersections: press seams open at that join.
A quick routine
- Sew a seam with an accurate quarter inch.
- Press it closed, then open, to the side that was planned.
- Place the next piece with seams nested and pinned.
- Sew, then press again before the next seam.
Do this for every seam and the top goes together as it should.