OK I will have to try using mine...........

Same here....love those pens.

I emailed Pilot, and the pens are acid free/archival quality- so you don't need to worry about them leaving something nasty in your quilt!

(They did include a "but don't use these for archiving- they disappear" note. Well, that's exactly what I want!)

I don't do show quilts, so these are actually PERFECT for art quilts- things that don't get washed. I've never figured out how to wash off the marks I do use (even just chalk) if I don't run it through the wash, and the air soluble markers don't last long enough.

I'll likely use them on my regular quilts too- since those all go into the washing machine.

Knowing that they are acid free makes me very happy, and seems to have been a concern for many (at least in older threads)

I just used one on some dark fabric and when I hit it with an iron the lines turned white. Cant get it to disappear. Washed it with no good results.it has always disappeared when Ive used it on light fabrics.

There was actually a thread on here recently where a lady did the test including using and not using starch to see if it came out or not. After that I started using the pens. The only downsize to it is that the lines are so thin that it's hard when I do backbasting; I need the line to show thru the fabric for that but I do like the thinness of the line.

If you wash them in Hot water the lines do come out but it has to be hot not warm water.

Have you tried it with Hot water; that's how you get them to come out and stay out

I got a set of 3 at Office Max for $6.