I've been testing bath bomb cupcakes for a month now and haven't a problem with mold and I just wanted to ask those of you who are having problems. Are you using distilled water using the same process you would for your emulsified products? Just curious because as I read the responses in this thread, no one has listed this as a step. I use the regular royal icing recipe with the boiled, cooled distilled water and I haven't seen any mold. HTH