The Importance of the Grainline
Warp (longways) and Weft (crossways) Threads
When you sew for pleasure, you should be able to obtain a good fit and fantastic results. To make your sewing easier and achieve the best results, use the best fabric you can afford and one that suits the garment you're making.
Woven fabric is made with long threads (warp) tensioned over a loom and cross threads (weft) passed over and under the long threads to weave a fabric type. The terms ‘twill’, ‘satin’, and ‘damask’ all reflect the style of weave of a fabric. They refer to how many threads the cross thread is passed over or under to obtain a woven effect. Fabric ‘straight grain’ follows the long side or selvage edge of fabric. It's one of the most important features of fabric for designers and sewers as grain controls how your garment will sit.
When choosing fabric, it's important to check that the long threads are parallel to the selvage and the cross threads are perpendicular to the selvage, otherwise you can’t be sure how the garment will sit. Fabrics that are not on grain tend to twist. We've all seen T-shirts that won’t hang straight on the line or jeans with seams that twist to the side. These are garments that are cut from fabric that does not have straight grain.
Look at the weave and make sure the fabric is on the straight grain before you buy as grain is hard to correct. If the fabric is patterned, also check that the pattern is aligned with the grain of the fabric so you can control the placement of motifs.