I’ve used a similar method using salt, and can be used in any chipped surface (eg: tanks).
You mix salt and water into a sort of paste.

For this example, paint the base in the shade you require.
Apply the salt paste to the base where you want it to peel away.
Mask and paint the stipe.
Once dry, wash the base and the salt will disolve taking the paint covering it, leaving a patchy surface.
Do the same for the number.

For vehicles (or any chiped paint effect item) basecoat in the shade yuo want the paint to be under the chipped paint (eg: metal)
Follow this with the salt-paste.
Cover with the base colour.
Wash away the salt to unveil the chips.

This can be done on multiple levels.
If you’re doing a camoflagued vehicle, you can start with the approach listed above, but before you wash the model, add the second camoflague coat over more salt-paste.
Once dry, wash away both layers of salt.

It’s easy and effective.
Try on an old model first to hone your abilities.

Cheers

Starscream

Thanks!