(One of the quilt blocks I plan to color.)
The following pictures show the final results of my testing.
#1-The Pentel Gel Roller is first and I consider the best of all the markers I tested.
#2- The Signo Uni-Ball marker
#3- The Zig Millennium marker
The Zig also did not have the nice roller action of the Pentel, and it also showed just a tiny bit of migration or bleeding onto a few threads on the fabric near the pen line. I could see less definition in the fonts as well.
#4- The Vellum Writer has a writing tip at each end of the pen. A fine tip, and a medium tip.
This marker could be 2nd or 3rd choice because it really did not migrate or bleed any more then the Signo or Zig, and it's a plus to have the two tips which did write fairly smoothly across the fibers of the fabric.
#5-The BIC Mark-it
With the BIC Mark-it I started to see unacceptable results. Definite migrating and bleeding for sure, but also a yellow or orange residue surrounds each letter in the writing. This occurred after heat setting and washing. The BIC marker did have a nice writing tip. But, the orange residue around the red marker lines is very detracting and I would not use it on fabric.
#6-The Copic marker
The Copic marker on fabric testing results were surprising. This was the suggested fabric marker for the Prayer Garden project. Looking at how badly it migrated and bled around each drawing line makes me glad I tested this marker before using it to color any of the embroidery. I could see it would migrate under the thread, or even onto the thread. The Copic marker also has a fine tip, and a wider brush like tip. As you can see both bled so badly on the fabric you can barely detect which is the finer tip lines. (it is the first "Copic")--- and which was the brush type tip. Glad I only purchased three colors to test this marker.
#7- The Spectum Noir marker
I guess I don't have to say--- the Spectrum Noir marker is the worst. As soon as the fine or wider of the two tips touched the fabric, the ink started to spread out like a puddle which made the individual letters difficult to see and read in this sample.