To make sure there is enough sugar for the yeast to feed on, the egg should float. But if it starts to tip over and not reliably point up anymore, the solution has become too strong, with too much honey sugar for the yeast to properly work, and fermentation will likely stall. The average range of 1.08 to 1.12 g/mL at which the average round, fresh-laid egg floats and points upward is also the ideal range of sugar content for starting a successful brew using standard yeast.
So, after all this, where do you start? Start with a fresh egg no more than two days old, of the roundest kind, weighing less than or about 2 ounces (57 g). Calibrate the egg in room-temperature water to make sure it sinks flat. Make your honey must, heat and evaporate as needed, let cool down to blood temperature, and add your egg.
If the egg sinks, the must is too weak. If it floats close to tipping or tips, the must is too strong. If it is too weak, add more honey, stir well, and try again. If itโs too strong, add a little water, stir well, and try again. As you can imagine, it is easier to start with too strong a solution and dilute it, than to start with a weak solution and try to incrementally dissolve more honey. If your must does need some strengthening, make a strong honey or sugar solution first, and incrementally add that to your must, not straight up undiluted honey.