I have found that when sewing several strips together I sew the strips from opposite directions that helps to keep them from bowing. Example: sew tne first two strips together than add the third from the opposite end that you sewed the first two strips, etc. Hope that makes sense.

As stated above it is the weave in the fabric - I have never been able to fix a bad bow :)

You probably cut your 1 inch strips WOF (Width of fabric) instead of on the straight grain. All strips should be cut on the straight grain to avoid this "bowing"

I agree with brenwalt on cutting the strips from the length of fabric. Be careful not to stretch as you are sewing, let the feed dogs do their work. Pressing should be able to help if there is only minor bowing.

I just finished a barjello quiilt and to stop bowing I sewed each strip one from the top the next from the bottom it takes longer but it works the other thing you want to let your feed dogs pull the fabric through do not pull or push it

I really appreciate all the responses. This is a very frustrating situation as I am sure there is an answer I just can't find it. I think most likely it is the answer about using batiks with regular weave fabrics. This is my first time using batiks.

I forgot to mention in my original post that I did indeed cut these strips LOF and I carefully worked on getting straight of grain first.

I am working with strips that are only 10 inches long (by one inch wide) so they are farily short. I am only making strip sets with 2 and 3 strips for 4 patches and 9 patches so it is not like sewing a 40inch long strip together with 10 other strips (like a bargello or other type quilt). The bowing is happening as a result of the sewing. I know this because they go into the sewing machine straight and then come out slightly bowed. I have played around with the tension but have not tried to vary the pressure on the presser foot. I will try that today. I will also try to use the walking foot and see but the walking foot on this machine (it is a Babylock Espire) doesn't work very good. PLus, I don't think I can use an "off center" stitch width with the walking foot and that is the only way to get a good scant quarter inch seam.

What presser foot are you using. If it is not an even-feed or walking foot that may be your problem. A regular foot will send the two fabrics under the needle at a differing rate. One is pushed and one is pulled. On short seams this is not a problem, on long seams it is. If you don't have a walking foot, try this trick when sewing the seam, hold the two fabrics together in you left hand up a little and somewhat taut. This is a trick used by seamstresses in clothing factories. Another is to sew the strips alternating top to bottom, bottom to top, that way the distortion cancels each other out.

To, maybe, narrow down the problem, can you take some of your strips to another machine or to a LQS and try the seams there? If they are O.K. you'll know it's your machine. If they still curve, ask someone else to try. If they STILL curve, try using identical fabric for both pieces........ Well, I hope you get the picture. It does sound like a feed problem. On my first machine I had to keep a little pressure on the bottom fabric to keep even.

Try holding the top strip up, just above the surface of the bottom strip...matching the cut edge. I do this when stitching curves, but lately, I've started doing it all the time..it seems to help some. Also, I agree that once you sew the one pair of pieces, when you are ready to add another strip...reverse and start sewing on the edge you ended sewing on. If you do like I do, and sew a pair together, set it aside, sew another pair...then make sure to put a pin in the ending edge...so you know that when you join two pair together...you want to have the pin from both be your start end. This in effect gives you the alternating stitching direction.
Lastly...remember to Press every seam... I use a spray bottle or can of sizing/starch...and "set" the seam..then open out, one seam at a time and press them to one side...all in the same direction.

Try sewing every other other strip in the opposite direction if your strips are stright. Hope this may help.