It appears that HP has identified some issues in the manufacturing process that might have caused limited “pen leak” in the affected cartridges, that includes some Collins inks. Collins purchases empty, new ink cartridges directly from HP to fill.
Collins HP CT Statement 12 11 2015
If you are having difficulties with HP cartridges from Collins, please contact us, and we will likely need the batch number from the cartridge, to verify it is part of the affected lot.