This invisible thread is great for quilting your finished project*.  It is a 100% monofilament nylon thread that offers strength and flexibility to sewing projects and easily blends with the material color.  I personally tested it with high heat, and it does not melt or become stiff.  Gutermann's is a high quality brand that can be trusted with your projects.
 
274 yards. Tex 14.
 
*I recommend using this on the top thread only (use regular quilting cotton or polyester thread in the bobbin).