Stain?
 

My mother-in-law did cross stitch squares and had a quilt made for each of her great grandchildren. Then had them hand quilted. Somewhere 2 of the ones for my grandchildren got moisture on them. Before we got them, the little blue preprinted dots for quilting lines have bled in a few places. These will be stored for quite some time. Would Synthrapol in a washing machine then pressing gently up and down remove the marks? Would it be ok to spin on gentle?

I would try vinegar on the blue dots first, perhaps dabbing on with a small cloth. Vinegar will remove the blue markers currently sold for temporarily marking quilts (even after the blue marks have set), so they might work on the cross stitch dots too.

Washing in Synthrapol might work. Keep in mind that you need *lots* of hot water for Synthrapol to do its work. A domestic front-loading washing machine does not use enough water; you need a domestic top-loader or laundromat front-loader.

There is no spin on gentle that I know of. However, spinning a wet quilt in a washing machine is safe for all but perhaps very vintage quilts.

You never want to press unwanted marks. Heat can permanently set stains and dyes and inks.

Have you tried washing them, in cool water? Some of the pre-printed lines where meant to be washed out.

Come to think of it, if the dots bled with a little moisture, chances are they will come out with cool water. I think the bigger problem is whether or not the thread used for the cross stitch is colorfast. Many threads that used to be colorfast are not manufactured colorfast anymore because of restrictions on the chemicals that can be used in them.

Theoretically Synthrapol should prevent bleeds from the threads from settling into the fabric. If you do wash in cool water and thread colors bleed, then several washes in hot water with Synthrapol should release the bleeds.

I happen to know she used DMC brand thread for the cross stitch.

If it is very old DMC, then it is likely colorfast. New DMC thread may or may not be colorfast, depending on the color, because of newer limitations on the chemicals that can be used to set dyes during the manufacturing process.

Not sure about the intentional mark removal, but my mom soaked some older hand embroidered squares that had some unknown stains on the them in Non-chlorine bleach for several days and it didn't affect the color of the thread.

I was just thinking, if your mil still has remnants of the threads and fabric she used in the quilts, you could create several samples to test for colorfastness. I would just machine stitch the embroidery threads onto the background fabric. If there is enough, I would cut this up into several test samples and submerge one in water to see what happens. If there is no bleeding, you wouldn't even need the other samples. If there is bleeding, you could try washing a sample in hot water and Synthrapol, etc.