Acrylics can be thinned to washes and that can soften the wet look. Rust isn’t wet. The water pushing it around gets stained and drops particles behind.
Get a mortar and pistil to grind up a dirt clod and make fine dust. Sprinkle that on a wet wash and it will give you subtle texture and the gritty look that is rust.
Build up washes and stop before you think you have enough and let it grow on you…
Less is more.
Go back and dry brush some off … add bits of yellow and oranges, puddles and blended spots.
Only when I want something to look painted from a can of paint do I want uniformity will I use it straight from the tube. The rest of my paints go on a pallet where I can mix Happy Rust Spots and the like, add water, add colors, thin and apply then pause and let it dry before adding too much, oh dang again?
