The marks come back when subjected to extreme cold weather. I tested it by ironing away and then placing in the freezer. The marks came back. I then ironed away and washed the sample and returned to the freezer. The marks still came back, but not as vivid. The pen has it's place like marking half square triangles, but I wouldn't use it on an area that would show.

Here's a link to the posts on this forum
http://www.quiltingboard.com/search....Frixion&u=&s=0

The posts sound like that old nursery rhyme,
When it was good it was very very good, but when it went bad it was horrid
Both great results and disasters.

I have tested every pen I could find, and haven't been happy with any of them. I am getting ready to test a chalk pen I recently bought and hope that it works better than the others. It is new and I got it at the LQS. I didn't buy the actual pen only the refills. They fit in a mechanical pencil that I already have. I wouldn't try those pens since the marks return in the cold. I wonder if you are supposed to erase the marks since there is an eraser on the pen.
Sue

I think it is wonderful for marking a sew line or cut line, so I will use these. I won't mark a quilt top, as I have great luck with a chalk or light pencil mark.
I don't get hung up on detail, as my quilts will be washed and washed and loved, none will ever go in shows or museums. So... I thank ya'll for your input.

These pens are fine to use for marking fabric for me. Many quilt bloggers have tested and retested them. One blogger, a chemist, tested the pens on fabric with starch, no starch, washed, ironed, and frozen. I forgot all the results but the chemical analysis showed the pens do not harm cotton fabric. Quilt bloggers are in the thousands online and one bad product, the news travels in seconds to millions of followers. Same with a great new product.

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That was my gut feeling. I live in the south where the cold is not a factor and don't plan on having a quilt show in my freezer. lol
I think it is fine for cutting and sewing lines. I think the pioneer women would have flipped over this! Lord, we are so spoiled, aren't we?!?!

ditto

Please let us know how the chalk pen tested out. Thanks.

yep i bought two but never used them. i don't care for things that iron off. i'm scared they will come back and on a quilt i'd be extremely upset if they did.