Just how much can you recover from a negative.
Well I was surprise when I found at "a lot" was the answer, after under exposing a shot by 4 stops, Efke IR820 at ISO12 instead of ISO1.5 I was left with a very thin negative but scanning the negative resulted in a printable image if going down the inkjet path.
Burke & James 8x10 270mm Efke IR820 / IR720 filter - negative scan
Click on image for full size.