I have no idea what brand ink is in the cartridges, however I read a posting
(a long time ago so take it with a grain of salt) that Rainbow carts had
Formulabs ink in them. Other than that all I know is that the ink worked
fine in all my printers and once empty I refill the cartridges with
Formulabs ink. I also have a set of test prints I created when I first got
my iP4000. The set consists of color charts (from the alotofthings website)
and photos I took with an Olympus c-3000 digital camera. The set was printed
with original Canon cartridges that came with the printer, then the Canon
tanks were removed and replaced by a set of USA (from tylermartin)
cartridges. After printing several purge pages to clear any residual Canon
ink from the printhead the set was again printed. This same procedure was
repeated with new Arrow cartridges, a set of freshly refilled cartridges
from my latest order of bulk ink from Alotofthings and then with a old set
of tanks removed from my i950 refilled with Formulabs ink which came from an
ink order placed well over a year earlier. All of these tests were printed
on Office Depot Premium High Gloss paper. Because of the wide variations in
age of inks and where the inks came from - Canon, Alotofthings & TylerMartin
it would have been reasonable to expect at least minor differences in the
coloration of each set. That wasn't the case. I couldn't detect any
variations and the only way I could tell the source of the ink on each sheet
was from the handwritten notations I made on the back side of each sheet.
Bottom line to me is that if it works, produces the desired output and
doesn't damage the printer then I really don't care what the source of the
ink is. Since all of the above meet that criteria, I go for the best prices.