Very nice quilt! Especially for a first!
I use Crayola ULTRACLEAN WASHABLE markers. I have had no problem washing any of the colors out. Can be found at Walmart and are relatively cheap. Congrats again on your great quilt!

Nice quilt.

Great job on your first quilt. Can't wait to see #2!

Cute quilt. I had the same issue on marking pencils not washing out, it took three washes using a prewash spray.

Thanks for sharing. Great job

Cute quilt, perfect for a boy. Have you tried marking with regular white chalk? Sharpen it with a pencil sharpener. You can also mark straight lines with blue painter's tape.