If reflective insulation is useful, why does the metal foil face of many rigid foam insulation panels have printing on it?

Does the foil cover ( probably intended as a vapor barrier) not have any value as reflective insulation - even without any printing?

If the foil covering has value as reflective insulation, is this value unaffected by the printing?

(I'm specifically thinking of the case where rigid foam board is used as attic insulation.)