All articles · 2026-09-18

Seamless repeats: the tile has to meet itself exactly

A repeat that is one pixel out shows as a line down every metre of cloth. Why vector tiles are easier to keep exact, and how to check the join before you print.

A repeat pattern is a single tile printed over and over, edge to edge. If the right edge of the tile does not match its left edge exactly, the mismatch appears as a vertical line every tile width, down the whole length of the cloth — and once it is printed, it is printed.

A tile with leaf shapes at the corners, a central dot and lines running to the edges: on the left a small compressed copy; on the right clean shapes and exact colour.
Left: 190 pixels, JPEG quality 60. Right: Logo mode, three colours. 10 paths, 205 nodes.

The elements that cross the edge are the whole problem

Look at the lines running off each side of the tile above. Each one has to continue exactly into its neighbour: same position, same width, same colour. In a vector tile those are coordinates, and coordinates either match or they do not — you can check them. In a raster tile they are pixels that have been resampled, and a resample is where a perfect join quietly becomes a one-pixel step.

Build it as a tile, not as a picture

Draw at a fixed tile size and place any element that crosses the edge twice, at both edges, at the same distance from the corner. Then check by placing four copies in a two-by-two grid and looking at the seams at high magnification. This takes two minutes and is the only test that matters.

A corner leaf and the line running to the tile edge magnified: on the left the line frays into grey pixels at the edge; on the right it ends as a clean straight edge.
Where an element meets the tile edge, at roughly 2.1×. This edge is the join — it is either exact or it is a line down the cloth.

Scale is a decision, not a default

The same tile at 5 cm and at 20 cm is two different fabrics. Print a strike-off at the real size before ordering a run: patterns nearly always look larger on cloth than they did on screen, and a motif that seemed delicate can turn bold once it is hanging.

Practical points for digital textile printing

  • Ask your printer for the tile size and resolution they want, and build to it rather than converting afterwards
  • Keep the number of colours deliberate — it affects both cost and how the print reads at a distance
  • Half-drop repeats hide the grid better than straight repeats; the drawing is the same, the placement is not
  • Keep the tile file separate from the repeated artwork, so one correction fixes everything

Vectorizing a scanned or photographed pattern gives you clean shapes to build a tile from. It does not make a pattern seamless — the source was a piece of cloth, not a tile, and turning it into one that joins exactly is work you do afterwards, deliberately, with the seam test in front of you.