I just spoke with an engineer at GQF about the humidity problems that I have incurred in the past month or so....we've had an extraordinary amount of rainfall recently. He stated that the most successful
way to monitor the moisture evaporation from hatching eggs was to weigh them. According to him, you weigh your eggs and record their weight. When you candle the eggs at 7 days and 14 days, you also weigh the eggs. During the 21 days of incubation, the weight loss should be 13%; therefore, at day 7 you should have a 5% weight loss and at day 14, you should have an additional 5% weight loss. The remaining 3% should
dissapate in the last week of incubation. My question is...does anyone actually use this method of monitoring the humidity in their incubators? Of course, you have to have the appropriate scales to weigh the eggs....which presents another question. What type of scales would one use? Where can the scales be purchased? Is this a practical way of monitoring the humidity?
I would assume that you do not weigh each and every egg in the incubator; rather, weigh designated eggs
that would be an accurate representative sample of
the incubated eggs. Your comments and ideas would be appreciated.

Blueboy, The Poultry Supply Catalogs have little scales for weighing eggs for sale. You know that each size eggs have a weight standard. It is a little seesaw scale with a wee cup at one end to hold the egg. Too much extra handling and records for me--I go by the candled air cell size and shape. CJR

The eggs from each hen will be different and unless you weigh a fairly large number that is a random sample size of your population you will not get an accurate idea of the weight loss of the eggs that do not hatch. For small numbers of eggs you would have to weigh each one. You need a pretty sensitive scale for this. You are talking about seeing a 2.5 gram difference in a 50 gram egg for a 5% difference this is only 0.09 oz (not even a tenth of an oz). Even postal scales only measure in ounces. Each gram is about 0.035 oz. There are 2.2 lbs (35.2 oz) in a kilogram and a thousand grams per kilo. The standard size egg is about 54 grams. Broiler eggs are much larger and bantam eggs are much smaller. Get one of the guides that show relative size of the air cell and judge it by eye for the amount of weight loss. A Guide to Better Hatching by Stomberg has this chart.

Rokimoto,
Thanks for helping me decide NOT to pursue the egg weighing method of monitoring egg evaporation. It may sound good, in theory, but sometimes, it is best to leave well enough alone.