They also say that it contributes to bacteria getting in the pores and killing the embryos. My last hatch was 92% and I'm a candling addict, so it's working for me..lolThe only thing I've heard is that candling eggs too much can cause too much Royals from your skin to develop on the eggshell disabling gases to flow in and out of the egg so if the eggs become glossy looking that means your candle too much I try not to kill that much I've had my most successful hatches when I've only candled 1 to 3 times.