I apparently am too fast for those pens - the friction of me zipping the pen ball along the fabric would make my lines vanish as quickly as they were drawn! I had to slow way down and that was annoying. (I also sort of don't trust them on fabric, I use them at work now.)

I use plain ol' tailor's chalk unless I need a really fine drawing and then I use the blue wash-out pens. I like the tailor's chalk because it always comes out, and I don't have to worry about "setting" it with the iron like I do with the blue wash-out pens. Plus it's extremely inexpensive and easy to find. I have it in white, blue, yellow and red - between those four colors I can always find one that shows up on the fabric I'm using.

It also reminds me of my gran, who was a quilter. :)

I use a Sharpie for tracing patterns, though. If it's going to be hidden in the seam allowance I love my Sharpies for marking fabric.

I have used them and love them. I have also used their highlighters. I ran my own experiment with them. I took about 15 different fabric scraps and wrote on them with a Friction pen and highlighter.I ironed them and put them in the freezer and the lines came back. Then I ironed them again and threw it in the washing machine with Tide.I put them back in the freezer and about half of them came back very faintly.
I also did a demo the same way for my quilt guild using various different marking methods. I don't remember all of them right now. I left them on the fabric as they were, I also ironed over them before I washed them. I did find that a lot of the blue marking methods were the hardest to get out. There must be something in the blue that makes it harder to remove. I used about 15 different marking methods and several colors of some of them.

Washing with detergent has removed every mark on my quilts, none have reappeared. Odd that some does.

I use them all the time & (knock on wood) I never had a problem with the lines coming back. Hopefully I never do because I really like using them.

I know some use the washable crayola fine line markers. The kind kids use.It has to be the Ultra-clean washable markers. I have tried them and so far no problems. I have used the frixiion gel pens but they do come back for me. They always leave a white line. I don't use them anymore unless I know it won't show up somewhere.

I think once you wash it, it won't happen again. If you iron it again, it will disappear again.

I use the FriXion pens where they won't show, for things like drawing the lines to make HST's, and I really like them for that.

For everything else, I use the Crayola ultra-clean markers. I LOVE them! I've used every color and even ironed over them, and they've always washed right out.

I ended up throwing out several of those Chaco chalk markers because none of the colors that I used (red, blue, yellow and grey) washed out and two quilts that I used them on were ruined. I've read that the white ones are fine, but once burned...

My bad...I should have tested them first. It was an expensive and frustrating lesson. :(

Never used them after researching their use on cloth.

I opted not to use them after I did some research.

FriXion pens are the only thing I have used that gave me a thin enough line. The only colors I had trouble with were orange and red, which did not completely iron out. I didn't go as far as washing whatever it was to test that.

I do use yellow Chaco, but don't like the way the powder gets all over the needle and bed.