NaAlH4 powder mixed with hexane was placed in two metal trays and dried by placement in a glove box antechamber under vacuum. After several days, the trays were moved into the glove box main chamber. As the powder in one of the trays was being transferred to a container involving scraping of a metal sieve and metal milling balls with a metal spatula, a portion of the powder in the tray spontaneously reacted rapidly, creating a pressure pulse which cracked the window at the back of the glove box. No injuries occurred, and the glove box window was resealed using tape within one to two minutes.
In addition to resealing the glove box window, a positive pressure of argon gas was maintained inside the glove box while the course of action was planned. Subsequently, the glove box was cleaned up by specialized hazardous materials personnel using natural bristle brushes and plastic utensils. Also, Teflon-coated magnetic stirring bars were used to separate the milling balls from the powder while avoiding metal-to-metal contact.