Hairline crack still safe to incubate?

[JH731]

Ordered some blue ameraucanas and all are good except for one. I noticed what looks like a crack in the shell but there are no raised surfaces and my finger nail doesn't catch on it. Is this safe to put in the incubator?

 

[subhanalah]

I use nail polish over cracks, even hairline cracks. I've had two hatch that way. When I didn't do it, the baby started but died

 

[JH731]

Thanks I'll try that out. I used clear polish and will put it in the incubator with the rest of them as soon as it dries. Thanks!