Got these notes from Nancy's Notions. The marks should brush or wash out if not steam pressed. Good luck!
# Chalk powder
# Approx. 4" long with cap on (3-3/4" long without cap on)
# Tapered point for easy markings
# Allows accurate drawing of both straight lines and freehand curves with the fine point pen
# Makes lines and marks more visible and easy to use with a straight edge
# Do not use on fabrics that are not washable
# Ironing or dry-cleaning may make the marks permanent
# Easy replacement; simply unscrew from the pen style point