Should you use a water or air-soluble fabric-marking pen?

Some say the air solible pens are the best, unless you live in an especially humid area or gets lots of rain. Then the marks can disappear very quickly; even while you're working. Some people still prefer chalk pencils. ANSWER: The answer depends on the project and the fabric. Will you be finishing the project quickly or will it be finished over a period of time? "Air Soluble" means they will disappear without any help from any other agent besides air. Air is everywhere so, in a very short time, the marks will vanish. Also, please read the brochure before using the marker because some of the marks might become permanent if ironed. The water soluble markers are nice to use because they do hang around for extended periods but, again, read the directions before using them. With any sewing aid, do a test on scarp fabric before use.