I don't know why some get such variants when using these pens. I've been using them for FMQ since they first came out and have never had any poblem with the markings showing up in cold temps. I put a ziplock bag of my practice samples in the freezer for over a week and the ink never showed up again. I'm wondering if some are purchasing pen similar but not the Pilot Frixon pens or it Pilot vary the ink from pens to pens. I wouldn't think so. They worked great for me when I was learning (an am still learning) how to FMQ. I purchased mine from Staples