Typically a retarding agent is added to the mix. this is normally "Cream of Tartar (or "Dope" in the plasterer's jargon) and care must be taken with the amount added.
Sida caadiga ah wakiilka xakamaynayay la daray in ay isku dhafka ah. taasi waxa ay caadiyan waa Cream of ilkeed (ama "daroogada" in erey-plasterer ee) iyo daryeelka waa in loo qaato xaddiga ku daray.