Hi All,
It has been a while but I have been researching hot to paint glass blocks and make the paint last, Well the best I can find is Pebeo paints seams to fit the bill. This paint is water base and once you have applied the paint to the area you want you put it into your oven at 300 degrees for 30 minutes and the paint is dishwasher safe ( top rack ) and safe for some of the cleaning materials. Also good for out door use. You can check out this site for useage and so on
http://www.dickblick.com/zz029/08/ . I also found this paint at Michaels arts supplys. I have bought some but haven't used it yet. Maybe to night. Good luck.
Jim