We have tried many brands of disappearing chalk, and Rabbit brand is by far our favorite! It marks crisp sewing lines on fabric that can be completely removed. The lines naturally fade away within 2 to 7 days (depending on the force applied while drawing), and will disappear immediately upon contact with a hot steam iron. Made in Korea.
Pro Tip: As with all vaporizable chalks, we prefer not to touch the chalk directly since the powder sticks to fingers. Some manufacturers of other brands of vaporizable chalk put a plastic sleeve around the chalk so that only two edges are available for use, and these kinds of chalk very quickly become dull and unusable. Rabbit chalk stays sharper for longer, and we simply solve the problem of powdery fingers by wrapping a piece of scotch tape from the center of the chalk (over the rabbit logo), around the thicker edge and then finishing it over the center on the other side. Then what you're touching is the tape, not the chalk itself. Used that way, it's clean and easy.
For information about which chalks we recommend for which purposes, please see the Chalk and Pencils section of our Sewing FAQs page.