The Corrections Association says conditions placed on the use of equipment designed to protect prison officers from catching communicable diseases make the gear pointless.
Spit hoods are included in a list of extra protective equipment to be given to officers in specific situations.
The hoods are lightweight, mesh garments that guards tie around a prisoner's head to stop them from spitting blood or saliva.
Corrections Association president Beven Hanlon says guards will be able to use the hoods only when they have been spat at.
The department says there's no formal policy yet on the use of spit hoods.