there are a number of different (disappearing) ink pens- the newest ones i know of are the frixon pens that when you press them they disappear- a lady at a lqs told me the colored ones leave a white line- the black one disappears.- any marking (tool) you use should be tested before using on your project---no matter what - or who recommended it- you should always test! i have ruined beautiful quilt tops because someone said---just use this it always comes out---well---guess what----not always... always test