One of the differences between art quilting and traditional quilting as that in art quilting, thread is almost always part of the design. The choice of thread in machine embroidery, in particular, can affect the look of the quilt.
Selecting a single color thread, a variegated thread, a thread that contrasts with the fabric or one that matches are all conscious decisions that inform your embroidery designs.
Thread painting requires a whole new level of thread selection. In this form of machine embroidery, embroidery stitches are layered close together so that the thread colors blend to create variations in color and shading.
If you've never tried these embroidery techniques, here's an exercise you might try. It's from internationally known artist Carol Shinn's excellent book Freestyle Machine Embroidery: Techniques and Inspiration for Fiber Art.
Freestyle Machine Embroidery: Techniques and Inspiration for Fiber Art is full of practical advice, tutorials, and beautiful pieces of machine-embroidered art. No art quilter's studio should be without it.
P.S. How do you use thread choice in your art quilts? Leave a comment below.