I’m diving into un-replied posts that were buried by our old forum software back in the day.
I actually used to use the Matte Black InkthriftPro ink before I worked here. It got to a dMax of 1.8+. After coming here in 2016, we released our Ultra-HD-MK carbon ink and this gets to 1.86 on some matte papers. It’s by far the blackest inkjet ink in the local solar system.
https://shop.inkjetmall.com/Shop-By-Ink/Piezography-Neutral/Piezography-Pro-HDMK-220ml.html
best,
Walker