Which statement regarding Puri patas is incorrect?

Puri patas may be done on metal surfaces.

Answer: Puri patas may be done on metal surfaces.
Puri patas are initially done on palm leaf and cloth but now may also be done on paper, not metal.

Puri patas or paintings evidently acquire their claim to recognition from the temple city of Puri in Odisha. It largely comprises the pata (initially, done on palm leaf and cloth but now done on paper as well). A range of themes are painted, such as the daily and festival veshas (attires) of Jagannath, Balabhadra and Subhadra (e.g., Bada Shringar Vesha, Raghunath Vesha, Padma Vesha, Krishna–Balaram Vesha, Hariharan Vesha, etc); Rasa paintings, Ansara patti (this substitutes the icons in the Garbhagriha, when they are removed for cleaning and fresh colouring is done after Snanayatra); Jatri patti (for pilgrims to take away as memorabilia and put them in personal temples at home), episodes from the myths of Jagannath, such as the Kanchi Kaveri Pata and Thia-badhia pata, a combination of aerial and lateral view of the temple with the icons and temples around or depiction of festivals around it.