The soda lime being referred to by R2elk is not true soda lime for rebreathers. There are products for scuba diving and anesthetic masks called soda lime that can be purchased to reduce CO2 levels (!! CAUTION !! there are 3 kinds of soda lime; a not true soda lime [more often identified as soda lime glass or soda flake] version for CO2 removal that can produce toxic hydrogen-peroxide fumes! among other things, a medical grade that can be purchased from a vet supply source that is safe but off-gasses small amounts of ammonia, and a product for scuba diving rebreathers without a color changing dye referred to as Soda Lime NI) a small amount of the soda lime will react with CO2 and change the soda lime to calcium carbonate (inert), heat, and water; then once finished reacting it will cool. It should be removed, tossed into the regular garbage while still warm, and then replaced. This is beneficial to CO2 reduction, but will increase the temperature and humidity, which means the vents need to be opened while using it. Medical grade soda lime and soda lime NI for rebreathers is NON-HYGROSCOPIC, and intended for use inside the tubing set up that patients breath through during surgery or that divers breath through while diving. It can be an irritant for skin and eyes, but it is not a requirement to rinse under water for extended periods of time. This stuff just gets warm during the reaction. It does not react with metal or melt plastic as those are the types of materials it is made to be in contact with. True soda lime will only react with CO2 to produce heat, oxygen, water, and calcium carbonate; all inert. I am simply using the cheese cloth right out of the package, and keeping it sort of away from the eggs. The heat produced may be enough to raise an egg a couple degrees. That would be bad!