The attached picture from EQ7 shows a design for a lined zippered bag that will be about 21" x 14", and will have the same piecing on both sides.
Can someone comment on if it makes a difference whether I cut the strips on the bias or straight of grain, and which would be preferable.
Thanks,
Carol

If you cut the strip on the bias your edges will all be straight grain. If you cut the strips on the straight of grain your edges will all be bias. I'd cut them on the bias so my edges had straight of grain.

will that make it keep its shape better? what's the benefit of having the edges on the straight of grain?

There will be less overall distortion when you sew. Bias edges are notorious for stretching.

The edges will be more stable (less stretchy)

OK. Now I know why, and will have my sides on the straight of grain. I know I can always get my questions answered on this great list!
Thanks!

I think if I were making this purse I would sew my strips on a piece of cheap muslin as a foundation. It would be a little sturdier and have a little more body. Just a thought.

Do you think that would eliminate the stretching problem if I did have bias on the edges? My problem is that I will need a lot more fabric if I cut the strips along the edges.

I would starch the fabric before cutting, cut on the straight-of-grain, sew the strips together, starch again, and then trim to the correct dimensions. Starch is necessary to stabilize the fabric so that the bias edges do not stretch out of shape and distort.

This would be my preference over cutting bias strips. It's possible to sew a bias edge to a bias edge, but only if you have heavily starched the fabric (1:1 starch:water proportions) before cutting the strips. It's better to sew straight-of-grain strips together, and then have to deal with the bias only on the outer edges. Since this is a purse, the edges do not have to match up to another block and trimming (if a bias edge stretches) will not cut off any points or other important pattern elements.

but will the edges tend to stretch after the bag is sewn together?

I have never had any problem with stretching when I do them this way, but it was just a thought.

I've sewn unstarched bias strips together with no problem.

Of course, it helps if the fabric is relatively stable to begin with.

Not if the bag is lined.

I do think the best idea is to foundation-piece on thin muslin. The muslin would provide additional stability to the pieced fabric. I would still cut the strips on the straight-of-grain.

The easiest seams are straight-of-grain to straight-of-grain. Sewing straight-of-grain to bias is much trickier. Sewing bias to bias is just about impossible unless you heavily starch the fabric before cutting so the fabric has no chance to stretch out of shape when you sew the seam.

I agree with the idea of a foundation fabric for a base. This is one of those "form and function" things.

Your original question was about why you would cut on the bias. That question was answered.

Now if you want to know how to make this pattern for a purse. That is a different story. This is where function comes into play. Thickness and weight really aren't a problem in this case so sewing strips onto a foundation fabric can be your answer to solving your bias issues. I really am not sure you are going to save that much in fabric in the end (I didn't bother to plot this out and do the math).

Personally, I would go the foundation fabric route. Just my $0.04. (Prices are going up.)

I made handbags for my granddaughters with jelly roll strips. I sewed the strips together, pressed seams to one side, then layed my pattern piece so the strips were at 45 degrees and cut them out, no starch, no backing, had no problem with stretching. Once you get the zipper & lining in there won't be any problem with stretching. Just pin often when inserting your zipper. I have posted this picture before, but you can get the idea.