The blue works great. The thing is, don't get it wet until ready and DON'T get it hot, then the blue will never come out. The purple also works great but will disappear within 12 to 24 hours by itself. So only use this if you are going to quilt asap.

I love those blue water-erase markers! As others have said, just be careful not to iron over the lines or you might set the color. When I use it to mark a quilt top, when I'm all done with the quilt I first do a quick cold water rinse cycle to get all the blue lines out, then do a full wash cycle with soap & warm water (to get all the Elmer's out!).

Super product for marking! On general principals I stay away from the red & black, but absolutely not problems.

I've used the water soluble blue pens on several quilts and never had a problem. Just a tip, if you mark a line n error, just use a dampened Q Tip to erase the error, rather than spray the area, works like a charm. Just don't iron over the markings.....then they can be a problem.

My advice is don't use the chalk pencils on the top of a quilt. They seem to have a waxie residue that makes the chalk adhere to the fabric. I had to wash my quilt twice and use Spray N Wash to remove the chalk. They're fine for marking on the wrong side of fabric.

As a longarm quilter, I don't wash my customers quilts but I do make certain I can remove the markings I place on their quilts. The mark be gone type pen is the easiest. I use a empty water bottle and add 16 oz of distilled water (this is a must) and 1 tsp of baking soda. be sure to mark it some way or you may accidentally take a swig of it and yuk!
Then when I want to remove marks - I have an empty pill bottle the fat short kind and a childs paint brush and paint the markings. They do not come back with this formula.

I have used the Air erasable fabric marker, and all marks have been removed easily.