I use Mettler 100% cotton;
- fine 60 wt. with green writing on the spool for hand applique. I have also used this to machine applique. This thread "melts" into the fabrics & becomes invisible.
- 50 wt. with purple writing on the spool for machine piecing, machine applique, & hand or machine quilting.
- 40 wt. with brown writing on the spool for hand or machine quilting.
60 wt. (green writing on the spool) isn't always easy to find, but it does come in MANY colors. Today @ Burkholder's I was pleased to see they had a selection of Mettler 60 wts. Hayes carries it too, but in a very limited color selection. Steve's doesn't carry this @ all. LadyFingers carries instead the YLI silk thread, which is more expensive & I don't think it's worth the extra cost. Just my 2 cents..., but YLI silk thread is what Jane Townswick uses for her hand applique work, so does Elly Sienkiewicz of Baltimore Album quilt fame. Also, I am pretty sure this is what Diane Gaudynski uses for her amazing machine quilting.
When I machine applique or do any decorative stitch with my sewing machine, I use YLI Soft Touch thread in the bobbin. I can only get it in white, beige, grey & black. This too is not easy to find. I usually get it @ Quilt Shows or dedicated quilting shops - LadyFingers does carry this.
When machine appliquing, if I want my stitches to be invisible, I will use a blind hem stitch or vari-overlock stitch with 60 wt. Mettler in a color that matches the piece to be appliqued. If I am using a decorative stitch that is seen, I will use a 50 wt. Mettler thread. If I want it to be noticed I'll use a contrasting thread, if I don't want it to be seen, I'll use a thread that matches the applique piece.
Whew!!! Is that too much information...?!