Black Copper Marans eggs are too dark to use a light. All but the 5 hatched and are doing great. The eggs that didn't hatch never began developing, probably not fertilized. All eggs were inspected with a light and were carefully placed in 100 degree water for less than 5 seconds, dried and replaced. All was done in 5 egg intervals and very carefully marked. Not a science and I don't suggest anyone do it if they aren't comfortable with the process.