@twotonebax
Paint your “underlayers” - as seen here it’s bare metal & rust.
Varnish the model and let that dry for 24+ hours.
Then get some hairspray and salt, “prime” the entire model with a thick coat of hairspray; while it’s still wet sprinkle salt all over it so the salt sticks to the hairspray. Let dry for an hour.
Paint the model whatever color you want the model to be when done.
Once that’s dry using an old toothbrush and hot water, rub away at the salt, it’ll dissolve and come loose.