the foaming agent producing more stable air bubbles is selected from the group consisting of alkyl ether sulfates having on average between 1 5 and 2 5 moles of ethylene oxide per mole of foaming agent sodium dodecylbenzenesulfonate and triethanolamine dodecylbenzene sulfonate most preferably the foaming agent producing more stable air bubbles is described by the chemical formula ch 3 ch 2 b ch 2 och 2 ch 2 c oso 3 m 2 wherein b has an average value in the range of 6 5 and 7 5 c is the average number of moles of ethylene oxide per mole of foaming agent and is in the range of 1 5 and 2 5 and m 2 is selected from the group consisting of sodium potassium magnesium ammonium quaternary ammonium and mixtures thereof even more preferably c is approximately 2 2 and m 2 is selected from the group consisting of sodium ammonium and quaternary organic derivatives of ammonium in a particularly preferred embodiment in accordance with the invention the foaming agent producing more stable air bubbles is cedepal u00ae fa 406 a commercial product available from the stepan company northfield ill the more stable air bubbles control the amount of air bubble coalescence that occurs during mixing of the gypsum slurry and or while the gypsum slurry is setting because the more stable air bubbles do not frequently coalesce with other air bubbles accordingly in the methods according to the invention the amount of air bubble coalescence that occurs is limited by adding increased amounts.