Marking quilts for quilting

It's no secret that I've been wary of the Frixion pens that a lot of people rave about. Just after Christmas, I bought a couple of colours from Paperchase and tried them out. They worked great; the lines went white and only vanished completely when well pressed but that was fine. I then tested my fabric in the fridge and the lines didn't come back, excellent, but in the freezer? This is what the once completely white scrap looked like...Yep, the marks came back, not as strong as they were originally but quilt-ruiningly there all the same. Which is fine for most people I would think, I mean, who keeps a quilt in the freezer? My issue is if I leave one in a car during winter snow, or in my conservatory with all the heating off if we go on holiday, does it get colder than the fridge in those situations? I could re-press, but I don't really want to, actually I don't want to iron any quilt sandwich to be quite honest, due to size and also due to the fact I don't want to compact the wadding any further.So I decided it was time to try these! Yep, bog standard kids washable felt tip pens. I tested all the colours on white unwashed cotton and it came out of the washing machine completely clean!So I've used them on a real quilt. With a bit of stain remover as well as standard detergent, I'm confident this is the best way for me. I always wash my quilts after binding anyway so it's no extra work, plus these markers have nice thick lines that I just cannot get from standard fabric markers. I used the green one this time as I'm still a bit scared of the mighty black one. I'm getting nearer to completion and nearer to wash time, wish me luck...