I use muslin squares, or maybe even old sheets. That way there is nothing to tear out and it is great with batting or without for a summer weight quilt. Just adding the back makes a nice, light cover. And the squares are on grain, so they stabilize the squares also.

I've used paper for strip quilting many, many times. I like to leave the paper attached until I've finished with the top and then tear it away. It can be a little cumbersome to do an entire quilt top, but the extra stability when sewing it very worth it. At one of my latest classes, I learned to used muslin squares as the base. They don't have to be removed and there's an extra "crispness" to the finished top. I've also experimented with using vertical strips with the horizontal ones and alternating the blocks. It certainly did give a different look the project! Whichever way you decide to strip quilting will work -- do what makes you the happiest.

I would never use paper as a foundation, I used muslin and worked great.

I would leave the paper on until put together in a quilt, although doing it in sections might be prudent. I see this as no different than paper piece blocks - the directions usually advise you to keep the paper on until the blocks are put together.

Thanks again everyone. You have all been so helpful.

Years ago, they left the papers on even after assembly for the extra layer of warmth, so leaving the paper on until the square is attached should not be a problem.

I sew mine to 10" muslin squares. When I'm finished, I just have to piece them together, put a backing on, do minimal quilting (usually corner to corner), and bind. I have also done them w/flannel instead of batting. Makes a lighter weight quilt but very comfy. Have fun. The good thing about this that the muslin does not have to be removed & is completely washable w/the quilt.

I do the old sheet thing, also. I just use the parts of the sheets that are quite worn but have no holes. The edges of a fitted bottom sheet are not worn enough, and would add too much extra weight. I have a box for trash fabric that would work for this. Sometimes I find a bed ruffle at a thrift sale that is just the right weight.

Remember to set your stitch length shorter so that it perforates the paper more. I have done it both ways and sewn on muslin and left in and then no batting. It all works for me.

I use scraps of muslin instead of paper. This way I use up some scraps, my blocks stay square, and
I don't have the mess of removing all that paper. Good luck with your string quilt, they are fun to make
and a good way to use up those leftover strips.