Hmm interesting, it's what Discmakers and Antrem state to use. i dont know that it's pigment based, but that sounds about accurate as it's not completely soaking in on some area's and it is on the others.
This is what it uses...
Black (HP 56, HP 27, or HP 21) Color (HP 57, HP 28, or HP 22) Photo (HP 58)
How would I know which are dye and which are pigment?
(Edit) just checked HP and they say to use pigminted ink! (UGH!) - and that the DYE is not water resistent.. (growl)! There has to be a resolution lol