What is in the 'stealth paint' that coats stealth bombers e.g B-2 spirit, and stealth aircraft, e.g SR-71, and how does it absorb/deflect radar?
Stealth paint doesn't reflect radar, it absorbs it by converting it to heat which is absorbed and dissipated by the airplane's structure. Paint is only one of several Radar Absorbing Materials available.
The paints known have suspended balls of ferrous material which absorb radar energy at certain frequencies and convert the radio energy into mechanical vibration, which causes friction and in turn heat.
Formulae for stealth paint seem to be closely guarded secrets. In electromagnetic test chambers we use radiation-absorbent materials (RAM) to absorb stray fields. I have seen stealth paints offered to motorists wishing to avoid police radar speed traps (some hope there!). They appeared to be ferromagnetic powder mixed with some kind of binder (back in WWII the Horten brothers experimented with carbon soot in glue). Certainly, ferromagnetic materials tend to be less bulky than other RAM solutions and their operational bandwidth can be optimised by tailoring the formula in various ways. Early stealth coatings were also reported in the press to wash off in the rain and the planes were repainted for every mission, which gives some clue as to the difficulty of finding a durable binder which is also electromagnetically transparent.