Siara,
I owe you an apology, since i said i would send you the flux that i bought, i damned if i can find it
I've a feeling it may have been thrown out by mistake, so sorry about that.
The rust streaks were done with Mig pigments mixed to a 'Milk' consistency with white spirit. This was then applied with a 5 '0' brush in fine streaks. Whilst still wet a slightly larger brush moistened in white spirit was used to feather them out.
All the best,
Sav.