https://www.allresist.com/resist-wiki-aqueous-negative-resist-based-on-gelatine/
Resist-WIki: Aqueous negative resist based on gelatine
Feb 16, 2022 - In the presence of catalytic iron salts, it is possible to photochemically induce a negative crosslinking of gelatine.
resist wikibased onaqueousnegativegelatine