Grainline refers to the direction of the fabric threads and shows you how a pattern piece should be positioned on the fabric before cutting.
On woven fabrics, the grainline usually runs parallel to the selvage edge. Pattern pieces will have a long arrow printed on them. This arrow should be placed parallel to the fabric selvage to ensure the garment hangs and fits correctly.
If the grainline is placed incorrectly, the garment may twist, stretch unevenly, or hang improperly.
For stretch fabrics, grainline markings may also indicate stretch direction. Most Katkow stretch patterns are designed so the direction with the greatest stretch runs horizontally around the body.
Always align the grainline arrow carefully before cutting your fabric. Taking a few extra seconds to measure from the arrow to the selvage on both ends ensures your piece is straight.
Correct grain placement improves fit, comfort, and overall garment structure.