Black mug printing shows brown

[Simong12]

In my post I mean trying to put black colour background onto a white mug. My template I use goes 3mm from top and 3mm from bottom of mug, if trying to do a black colour mug with a colour txt the black comes out with a dark brown.

[bshadown]

Might be overcooking at léast thats what i see when i use too much heat on any sublimation