Originally Posted by Sewnoma

I don't trust them, personally. They weren't designed for fabric use, and so I don't know what chemicals are in that ink and what they do to cotton fiber over time.

I have another problem with them aside from that concern: I tried using them anyway just to see how they did and apparently I draw my lines really fast - the friction of the pen tip running over the fabric vanishes the lines on me as soon as I draw them! LOL

I had bought a 3-pack; I took them all to work and use them there. Handy in meetings when people are being wishy-washy and changing their mind on me, I can sigh and dramatically erase stuff I had just written down. LOL

Originally Posted by Onebyone

Friction creates heat so the marks have to have friction to go away. Tumbling in a hot dryer will work.

I use them. The gel washes out just like any other marking pens you use. I washed a sample after ironing and the marks did not re appear in the cold freezer. The sample I did not wash the marks came back. I trust them more then I trust the disappearing marking pens or the blue wash out pen which can be set permanently with heat. And I don't care if my quilts don't last for generations. They can make their own. LOL

Originally Posted by Carol Wilson

I use these pens all the time, instead of an iron I use a hairdryer that way it does not "flatten" the quilting.