Check the Grain Line Before Buy Fabric:
Some fabrics cannot be returned to grain perfection. These include most knits, fabric on which a design is printed off-grain, synthetic woven and blended fabrics that have been heat-set off-grain during processing and many fabrics that have a finish (such as permanent press or stain resistant).
In many cases the grain may have been pulled out of shape as a permanent finish was applied or it may have been imperfectly rolled on the bolt. If it has been imperfectly rolled, it can be processed at home and returned to grain line perfection. Many permanent finishes lock the grain line into place, however and it cannot be straightened.
The consumer can determine if a fabric is on the grain by unrolling a yard or so from the bolt while still in the s':ore. Fold the fabric back, matching the selvages. Check to see if the crosswise grains run at right angles to the lengthwise grains. Check on both sides of the fold of a bonded or printed fabric to be sure that both halves are on the grain.
If they are not, no amount of correction at home will perfect the grain. Carefully examining the fabric before purchasing it will let you avoid off-grain cuts.
Preparing the fabric for perfection of grain:
To check the perfect grain, clip into the selvage near the end and pull a crosswise thread over the entire width of the fabric. Cut along the drawn thread. Fold the fabric lengthwise, matching the selvages and smooth out on a flat surface. If the straightened raw edges match, the fabric is on the grain and ready to use.
Knits and other fabrics with hard-to-find grain lines:
If a crosswise thread cannot be pulled to find the true crosswise grain, open up the fabric and lay it so that one of the selvages follows the straight edge of a table. The true crosswise grain can be established by a T-square or yardstick laid at right angles to the table edge. A basting line following this straight edge will mark the crosswise line.
Other possibilities are to follow the wale or course of a knit or a woven-in or knit-in design line to find both the lengthwise and crosswise grams.