Liquid iron

Iron primer
can be made to rust with the help of an oxidizing agent
for unique rust effects on various surfaces

Apply the liquid iron to the painting surface with a brush, either undiluted or diluted.
Then spray the wet or already dried surface generously with the oxidizing agent.
This process can be repeated several times until the desired rust effect is achieved.
For a rough surface texture, the liquid iron can be combined with iron filings.