This is the same sample after a few minutes in the freezer. I don't know how cold the fabric has to actually get, I just put it in the freezer, and the marks came back.
I did another sample that I did not iron the marks away, I just wanted to see if the marks would wash out.
This is the first sample with all the over marked parallel lines, and after washing and re-freezing, the marks came back. Only the over marked lines came back, but they did come back. Once again, I ironed them and they went away.
This was the second sample that I did not iron before washing or freezing, and the marks did not reappear.
So, what does all this mean? The majority of quilters that I have talked to, or who have talked in classes about these markers do not recommend them. Their concern is that the chemicals from the pen are still in the fabric even when the marks are gone. And, if the fabric were to get cold enough the marks would reappear. Now would this really happen? Would someone actually put their quilt in the freezer? Probably not, but what if the quilt was left in a cold car, or taken or shipped somewhere very cold? I could see this happening. And, I don't know how cold is cold enough to make the marks come back.
On the other hand, if you marked lightly, and did not go over the same line repeatedly as I did in one of the samples, the marks disappeared in the wash, never to be seen again even in a deep freeze. So, I will leave the decision up to you. I will say that I use these markers, especially for the diagonal lines drawn for HST. What I like about these markers is how easily and clearly they mark the fabric, it is a nice thin, clearly marked like. I think there are pros and cons to all types of fabric markers, so hopefully this post gave you some information on the Frixion Pens.
I would love to hear your opinions on these pens, and as always, I appreciate you reading.