For somebody who is an "ex-metrology guy" I find your manner of presenting your findings to be confusing. One could get the impression that you are commingling apples and oranges and calling it all fruit - I hope that's not the case. Starter cartridges are 64 ML, replacement cartridges are 80 ML. Each size needs to be evaluated separately and the data presented separately. And please don't further muddy the discussion by introducing CM3 when only two variables are needed: grams and ML. Your data indicates that there are about 0.883 ML per gram - (because you say that 15ML weighs 17g)? That is what we need to know (if the information is correct) for including the specific gravity adjustment into the conversion between grams and ML. And you have found that an empty cartridge weighs 63g. So, how much does a FULL NEW 80g cartridge weigh? Could you please confirm that measurement, then subtract 63g for the empty shell, then multiply the difference by 0.883 and we should then have approximately the content of ink in ML, if you other measurements are correct.

Dear Mark, pleas do not question someone competences, I feel all those "ifs", direct and indirect, are not needed in your reply. I am not questioning yours...

This forum is not for metrology experts, so it would be useless and time consuming to prepare full detailed report with error analysis etc, it is not my intention.

To the point: what is not clear for you in my previous post with measurement results? I think all needed data are there including the exception (starters for P800).

There were only two starter carts for P800 in the poll. I have not included them in the point 1) stating new cart weight (or rather mass, if you want t o be more precise) what I clearly written. I have written about 64 ml P800 starters to show that the same amount of ink remains in them at the end as for regular ones.

The full new

regular cart weights 143 [g] (+-2 [g]) and it is the same for P800 and 3880.

So, 143 [g] - 63 [g] = 80 [g] of total ink in a new cart (EXCLUDING P800 starter carts).

Ink density is 1.13 [g/cm3] (or if you prefer 1.13 [g/ml], units don't matter). So, that gives 80 [g] / 1.13 [g/ml] =

**70.8 [ml]**.

Because of possibility of not precise measurements of small numbers of mass (17 [g] in 1 [g] steps) the density might be a bit different. Common value, also repeated on this forum, is 1.08 [g/ml] but I think it can differ among manufacturers and ink types and colors.

I have 30 "empty" carts so I can measure average ink density more precisely if anyone gives me a trick to open plastics quickly.

And another information is that ~15 ml of ink remains in every "empty" cart, similar in proportion to the values presented on the first video I have pasted previously (40 ml remaining at the end, the new cart capacity is 225 ml, and nominal value should be 220 ml). Similar proportions are reported to all Pro Epson photo printers (not sure about Px0k series). From consumers point of view it is unfair, at least in Europe.

Any other questions?