Maybe use another type of stabilizer like cutaway and slide another piece of felt under the hoop whenever you sew the last frame. It looks like it sews around the whole border again in the last frame.

I would have used wss, seems like felt, especially if you add another to cover the back will be a bit bulky for a bookmark. Hopefully some of the more experienced ladies will have some good ideas. Good luck!
Debra

Perhaps hoop the wss, use cut away stabilizer for the bookmark itself , and either a second piece of that or a cotton fabric for the backing. Then just go around the edge with a wet washcloth (after trimming very close) to remove the wss. This would end up thinner.

I do lots of bookmarks to give away. I embroider on the fabric with stabilizer. I usually use hefty stabilizer. I then slide a piece of solid color fabric underneath before the last stitching if it has a satin stitched border. If it does not have a satin stitch border I sew the fabric backing on using a tight zigzag stitch after the embroidery is finished. You can embroider something like a name on the backing fabric if desired. Hope this helps.

I believe it is designed to place a backing/fabric on the back before doing the last stitching. It's like doing in-the-hoop designs. I did that one a while back with woven fabric. Felt should work well but yes you would want to cover the back. Since you have already completed it maybe you could glue fabric to the back.

I have done that bookmark - if I remember - there was not a outline to stitch the back on - so I went back to the beginning and added it - so that I could cut the fabric on the front and the back away - using WSS - then went to the satin stitch and when it was finished just rinsed it out.