Thanks Cem. I guess it would also be useful to know the weight of an empty P900 cart. Can someone with an empty oblige?

My thinking was that if the P900 carts really are the same as the P800 / 38xo ones, then we could impute the usable ink by weight. I think that the 3880 carts were around 142.7 gms full and 76.2 empty, a difference of 66.5gms. We don't know the SG of the ink, but it's unlikely to be less that 1. The accusations of too much ink left in these carts is well known.

If the P900 carts empty weigh the same as the 3880, a big if, then that's 45.3gms of usable ink by weight. That's a much smaller gap to the nominal volume of 50 mls than for the 3880. (Yes, I'm assuming an SG of 1 but it's the *relative* difference between P900 and 3880 that I'm really interested in.)

It would be useful to get an empty P900 cart measurement to verify or vary this estimate.