I've read several contradicting articles on whether wash-away pens should be used to mark embroidery fabric. I've never had any problem with them, but now I hear they're bad, can run, may never wash out and become permanent, or ruin my embroidery fabric.
Should I toss my pens in the bin, or continue using them?
Don't throw them in the trash. Test them.
This topic comes up now and then, but should not cause any alarms or unnecessary fear. There have been those who have had bad experiences, while others love these pens. I fall into the latter category of stitchers.
My initial answer is yes, water-soluble fabric marking pens and wash-away markers (not iron-on pens or pencils) can be quite safe, and do indeed create a temporary mark. But, the use of these pens will depend on three important things: the brand of the pen you are using, the fiber content of both the embroidery fabric and thread, and whether you intend to thoroughly wash the item after stitching.
The third item, washing after stitching, is where many people give up on the pens. This is also the cause of their seemingly bad reputation.
The term "washable" is the key to using a water soluble marking pen successfully in a project. The ink must be thoroughly removed from the fabric by soaking or thoroughly rinsing the item in room temperature water. The emphasis here is on thoroughly! Better still, launder the item with a mild soap such as Orvus paste and rinse properly after completing the project.
Holding the fabric uder running water for a quick rinsing, dabbing the fabric with water, or wetting the piece down with a spray bottle until the ink seemingly disappears will not properly remove the ink. If the ink is not removed, it will likely reappear after the fabric dries. This may be days, weeks, months or even years after rinsing, as the ink may reactiviate due to exposure to air or light.
Because the ink must be actually removed and not just rinsed or dabbed until it disappears to the naked eye, fiber content plays and important role in your decision to use a disappearing ink, water soluble fabric marking pen. Use the same rule of thumb you would use for garments - if the embroidery threads or fabric must be dry-cleaned or shoud not be washed, do not use washable ink.
If you do choose to use these pens, select a pen that has a fine point that will make the thinnest line possible, and cover the line with your embroidery. Some less expensive brands of these pens make a thick, ugly line that seeps into the fibers of the fabric and is difficult to completely cover - and difficult to remove. I suspect that this is where many stitchers run into problems, as so much ink has seeped into the fabric that it's difficult to properly remove.
Before using any wash-away marking pen or pencil, test a small area of the fabric. If the line bleeds into the fibers and leaves a blob of ink instead of a clean, thin line, don't use the pen. Then, wash the test sample and allow it to dry. If the ink returns, try another brand.
I do use these pens for marking my fabric for most hand embroidery or surface embroidery projects. I prefer the pens made by DMC, and I order them by the box because I use them constantly. The lines made by this brand of pen are crisp and thin, and I've never had any problem removing the ink. Nor has the ink ever reappeared, because I properly wash each piece after completing the embroidery. There are pieces in my collection that were worked years ago using water-soluble pens, and no traces of ink have reappeared. This is due to properly removing the ink from the fabric.
I've been active in the needlework business for 30 years, having worked for two major thread producers. I have used these pens successfully to mark designs for stitching on embroidery projects (including many seen here on the About.com Embroidery site), to mark the centers of cross stitch fabrics or quilt blocks, and in garment sewing, and have always had excellent results.
Remember, these pens have been around for decades, and have been used by many stitchers with outstanding results. If they were not being used successfully, or were causing damage to the projects of those who use them, these pens would have been pulled from the shelves long ago.
My best advice? Don't let someone else's bad experience sway your decision. Always test any temporary (or permanent) marking method to make sure performs as expected, and that it doesn't bleed or smudge making it difficult to follow your stitching lines.
...and remember, When in doubt, don't use the pen. Use an alternate marking method instead..