Thank you for yours responses!
Has anyone else had the same problem as Mick with Schneider Platinium IRND?
Do you thing it's a good idea to buy only a 0.9 IRND filter? If I need 1.5 for example, I would mix it with a standard 0.6 ND. The pollution shouldn't be that harmful than. Am I right? I just don't have budget yet for a complete set of IRND as I've just bought a new ND set :-/
The interesting thing is that it seems that the Epic is much more susceptible to IR pollution than RED MX....weird.