That's what I used, candle wax. I usually keep candles on hand and after I got over the shock and dismay of what happened, I grabbed the candles, lit them up and started spackling. It worked beautifully on these two and in all honesty, I wasn't expecting one of them to live to hatch as there were patches of egg gone, exposing the tough outer membrane. Luckily my hen's eggs seem to have tougher than usual outer membranes.Some folks use wax, I have heard of duct tape being used too.
I'm a believer in Candle Wax now.