Since you don't like tearing off paper, and a fabric foundation is too heavy for your purposes, how about used dryer sheets? I save all of mine and then press them lightly to store in a stack. They're really light-weight and don't need to be torn off.

I don't do paper piecing either. I also don't care much for starching.
But I've done stratas before by pressing freezer paper on the back of the whole already sewn strata strip; then cut out the shapes -- especially if the edges of the shapes will be on a bias (like diamonds). I sew the shapes together with a short stitch length; crease the paper along the seam line; run my awl along the crease on the paper; then peel the paper off easily.

Jan in VA

I can be done, just make your blocks a bit bigger than required and trim them down after sewn. Starch your fabric twice on the back before sewing. Why twice? Try it to find out!
peace

Try looking at quiltville. Search was quilted string patterns .she is using a light weight fusible ?.. I made some and also but a soft fusible behind or she has other suggestions.

you can always use a very lightweight interfacing- which could be left in but the extra weight is next to nothing. of course you can piece without a foundation- it isn't as easy, but is certainly 'do-able'
the wash away products tend to be a bit expensive- but lightweight interfacing is pretty cheap. I've also used the least expensive, lightweight muslin i can find- the 99 cents a yard stuff...it too does not add much weight- interfacing is really easy to quilt through too- don't even really know it's there.

Looked and looked but couldn't find any reference to using a fusible.....maybe a link? TIA!

I'm trying to sort all this about "string" quilts and foundation piecing out! New terms to me: "strata"=the pieced blocks, right? "Lasagna" quilts=basically a jelly roll quilt, right? I've wondered if using e.g. muslin as a foundation would make the quilt more bulky once you add batting and backing? "Flip and Stitch" basically same as string piecing but string pcg are strips in a row on the backing and F+S can have the strips arranged around a center focus fabric? There are two threads about baby quilts I love that say they are basically a crazy quilt block using the flip & stitch technique: Focus Fabric from a Scrub, and Finished! by weasier22. I finally found one or two tutes on doing them this way or I'd never have figured it out myself! I hadn't been grabbed by string etc. piecing but am beginning to be hooked in! So many questions, so much to learn! And about using used dryer strips as backing, I'm going to have to quit cutting them in half to be frugal and leave them whole! Whew!

Like this idea, it goes on the list to try!

Pollytink, you can use muslin. It will add a little to the weight of the quilt but not a lot unless you use a very tight-woven muslin. The el cheapo muslin works best for this type of backing LOL .

three words for you: "Ditter's string quilt" -- it's got everything well explained for doing it quilt-as-you-go.
(type it into the search box at the upper right screen corner)