How do you do it?

Make a small cut into the selvage edge, enough to "expose" the weave or threads. Take one of the threads that runs accross the fabric width and pull it out. Because the thread or fiber is secured at the opposite selvage , it will gather up , you can pull till it breaks pulling out that thread leaving a line, then cut on that line till you reached the point where the thread broke and pull it again. On printed fabrics just pulling a little and working the gather across the fabric will take that printed thread and it will be noticable because that printed thread thread will not be in the same place in the print . If you saw this done once its a whole lot easier than trying to write it to explain.
NOTE: do not use this method on most batiks, way too tightly woven, it will just make you crazy. In this case if a batik is really off grain ... I let er rip! to straighen.

I was taught a quick method to straighten grain. Simply pull on the bias of the fabric from one corner to the other. Do it both ways. Then when folding to cut you can see the "drape" if it was not cut straight. Then, with selvedges matched I move one cut end over until the fabric hangs straight when folded. This keeps my cut strips nice and straight with no dog legs. I was never taught the pull a thread method but it does sound like it could come in handy on some fabrics where you really need the straight of grain.

It is VERY important to cut clothing fabric on grain, and pulling threads is the easiest way to accomplish that. If the pieces are cut with the grain running wrong the garment will not hang right, and if any directional elements are present it won't look right either.

I have done it with quilting fabric that was really off grain, but not often. The pieces we use for quilting don't have to "hang", and they are smaller. We can fussy cut if we're concerned about matching stripes or plaids or other design elements. And even if the grain is off a little, the cut will not be on a serious bias, so it is usually okay. When we line up the selvages, we are trying to put the fabric on grain, and that is usually enough for quilting.

Dang! I took auto repair :lol:
David

Thanks for the explanations. I'll have to try it and see what happens. If I learned that back in sewing class I have forgotten!

Don't feel bad, David. I took band! lol

I remember spending lots of time helping my mom pull fabric to get straight of grain. Now there is so much sizing in the fabric that you really must wash it first before pulling. Then, if you are cutting strips you end up losing a lot of fabric because it was not cut on grain. I agree that if it's for pieces, it is not quite as important.

tearing fabric is recommended by Harriet Hargrave and while you loose fabric in the process - it is amazing how far off some fabrics are.

I started a quilt club last year, and one of the first people to come was a retired Home Ec teacher. She had to pull threads to straighten her fabric. I'm sure she shuddered whenever I told them just to cut and not straighten the fabric. Needless to say, she didn't last very long.