Originally Posted by melnjerm @Sally Sunshine
Thank you for the comfort! No, the humidity was 65% for lockdown only. All the days prior were at 48%. This was my 1st hatch that ended so badly. It was just such a shock! I'm waiting for my shipped eggs to hatch now (in the new Brinsea). They are at 13 days now and I've had to pull 11 out of 26 so far.😕 Lots of saddle shaped air cell eggs still hangin in there! We shall see!
for BCM humidity could be too high, most of us start out at 30% with marans, legbar and dark OE. and then at day 7 candle adjust the humidity as needed for weight loss.
you have calibrated hygros and thermos?
you run at 99.5 for fan model right? try running a calibrated 100.5 never going below 99.5 and never above 102 for those types of eggs.
WHY do we need less humidity to get the best weight loss for colored hatching eggs during incubation?
Marans being the best example!
Bj's purty eggs are in the image below
First you have to understand egg shell composition!
Eggs with white shells are made almost entirely from calcium carbonate (CaCO3), and 5%est. of egg shell is made up from other minerals such as calcium phosphate, magnesium carbonate, and various proteins. As an egg is produced, it goes through the hens oviduct, which consists of five parts, Infundibulum, Ampulla, Isthmus, Uterus and that there Vagina.
Tan eggs or brown eggs can vary in color depth, the color seen on these eggs is actually a pigment/coating applied during the last few hours in the hen’s uterus and isthmus, see image below. A tiny amount of this brown pigment over a white egg will produce a light tan egg, a lot of this pigment will produce the dark brown Marans eggs. Since this color is not actually part of the shell and "painted" on the surface you will see that it can be rubbed off and scratched when its still wet, note the scratched eggs in the image above.
Now we should all understand this part......
A Marans hen sends out thick coatings of pigment/protoporphyrins, which are by-products of blood synthesis, and deposited during the long hours passing in the uterius/egg duct and then finally in the BLUME stage, and those proto things, well they fill in thousands of spores in which create a dark beautiful egg, and in turn make the shell thicker.
Of course there are other factors involved, thickness of shell from calcium intake, size of eggs, and so forth, but with understanding the entire egg shell composition we can easily understand WHY there is a need to lower incubation humidity compared to commercial hatcheries that hatch white eggs, and why some breed eggs need a much much lower incubation humidity to reach the correct weight loss.