DSF

I have just done another water bottle with black writing i have done and at 160 deg for 130 secs and still not black.
Answers please. Just dont know what it could be.

Print some black text and place this on the water bottle in an unused space. Press at 160 degrees for 90 seconds only. The metal water bottles get hot very quickly so don't need as much time. Use light pressure otherwise you can cause the water bottle to cave in.