Here's the thing about Jack Black — it isn't a flat, dead black. It carries a warm brown undertone that emerges beautifully by candlelight and low lamplight, which makes it far more flattering than a harsh jet black. The best way to use it is to be bold: drench the whole room — walls, woodwork, even the ceiling — to create a proper cocoon. Take the woodwork up to full gloss in the same colour for a bit of depth and reflection.
When you want to break the black up, the golden rule is never a blue-white. A cold, brilliant white will fight the warm undertone and make the black look grubby. Go for a soft, warm off-white instead. Paint & Paper Library's Sand I (LRV 95.4) is a cracking choice — clean and bright but with enough warmth to sit happily against the black. Dulux Moon Shimmer (LRV 92.3) works similarly if you want a softly creamy neutral. Both give you that bit of breathing space without breaking the mood.
If you'd rather layer a mid-tone in than jump straight to off-white, Mylands Alderman No.60 (LRV 58.8) is a lovely greyed neutral that bridges the gap — useful on adjacent walls, joinery in a connecting room, or a feature piece.
The "but won't it be too dark?" question always comes up. Honestly, dark rooms read as intimate and considered, not gloomy — provided you light them properly. Use warm lamps at low level rather than relying on a cold overhead pendant, and the black will do exactly what it's meant to.
To finish it off, bring in antique brass hardware, old leather, and dark timber furniture. Those tactile, aged materials are what make a black scheme feel rich rather than flat. Avoid chrome and stainless — too cold and clinical against this warmth.
Get the off-white right and the metals warm, and Jack Black will be the most atmospheric room in the house.