Use
Shake the Rust-It well before use. In hot weather decant a small quantity into a small jar or suitable paint tray and keep the jar lids closed.
Using a sponge applicator apply the first base layer of dark rust colour and allow to dry.
Apply a second layer of dark rust if required, using a stippling action to give a varied finish and allow to dry.
Apply highlights with light rust on fresh rust areas, rain run effects etc. with a sponge, brush or microbrush as suitable for the area. Build up extra layers if needed.
To create rust stains and runs apply a dap of light Rust_It and spread downwards, tapering the run to nothing.
Repeat with a much smaller dark rust dap but don't spread so far to create a 'spine' effect of older rust.