A nationwide prison safety review is being held following a series of attacks on prison guards.
The Corrections Department says it is reviewing all furniture in prisons, to ensure nothing can be fashioned into makeshift weapons.
Chief executive Ray Smith says the review began after a Hawke's Bay prison officer was disfigured when boiling water was thrown at him by an inmate in June.
Mr Smith says an attack on two guards by two inmates at Waikeria Prison in Waikato at the weekend, has proved a review is essential.
An iron pole, fashioned out of items in the cells, was used in the assault.
The department is working with the Corrections Association to identify what items are risky in the hands of what kind of prisoner.
Association president Bevan Hanlon says hot water is one of the most obvious concerns, but there are a number of items to be looked at.