Here are the results of the first week’s observations. There are some interesting observations, and some obvious conclusions.
Firstly, there was some up and down fluctuation of mass for the first couple of days. I’m not sure why this was the case, but a longer observation period may shine more light on this.
Secondly, the pottery ink bottle (with new cork) is among the top performers, with 100% retention.
Thirdly, and this is the obvious conclusion, even at this early date, the simple glass insert in a metal holder with a fairly loose lid (C) is doing abysmally. In fact, it is doing worse than the open control container. Ironically, this type is among the most available today.
(As a side note, this puts me in mind of the old axiom about suits of armour in museums: their small size is not because the people in medieval times were physically smaller than we are today. They are smaller because the surviving suits were ornamentally made, largely for the young nobility. The truly representative armour was always used to pieces, literally, on the battlefield; too valuable to store away where it would be preserved for posterity and scholars. Perhaps the really efficient inkwells were used so much that there aren’t many left?)
Of significant contrast is the fact that the wooden-cased inkwell (D), despite a similar overall design to C, has almost no loss.
We shall continue with the experiment in the weeks to come; expect the next batch of results a week from today.