The terminology of "Dry" hatching isn't quite right. If your incubator RH is too low mortality rate increases. The maximum overall water weight loss of egg should not hit 18%. It's quite a range that is good conditions 9% to 18% weight loss of egg.
This more or less equates to you should not let RH hit lows of 20% or less for any extended period of time. Dry implies no moisture and that is terminal in most environments. Not adding water may work in England and wet areas but wouldn't work in Arizona for example. The word "dry" only means drier than what most manuals are implying is proper. I experience lower hatch rates if my RH is much above 40% yet research indicates 45-50 is optimal. Not my experience at all. And if my RH runs lower than 25% during incubation I also experience lower hatch rates. 30-35% in my experience is optimal.
Surface area of water is what maintains RH, by substituting different size containers from double shot glass to small tea cup I find what works to maintain 30-35% RH and this is dry incubation compared to incubator manuals and online sources other than BYC. Our experience is proving different than the status quo.
