How to stitch sashiko curves and circles
Curves ask the stitch to change direction gradually. The easiest way to keep them smooth is to give the thread more frequent chances to settle instead of pulling a straight-line rhythm around a bend.
In this article
Mark the curve clearly
Use a line you can see without pressing hard on the cloth. A faint or broken curve encourages the needle to correct the shape by pulling the fabric instead of following the route.
Test the scale on a scrap. A small circle may need shorter stitches and a finer thread than a broad arc on a household cloth.
Shorten the stitch group as the curve tightens
Load fewer stitches around a tight bend and smooth the cloth after each group. The line should turn through small changes rather than making one sharp correction at the end.
Keep the spaces visually balanced. A tiny change in stitch length is less noticeable than a line that has been tightened into a polygon.
Check the circle from a distance
Hold the cloth flat and look at the complete shape, not only the section under the needle. The eye reads the curve as a whole and will forgive small hand-stitched variations if the outline remains smooth.
If the fabric is puckering, change the tension or material pairing before adding more stitches. A larger needle or heavier thread will not fix a curve that is being pulled too tightly.