On Mon, 27 Jan 2020 08:21:45 -0500, J-J wrote:

Not really a home repair issue, but since a lot of other projects can
overlap and there are a lot of responsive folks in this group....

I am currently trying to test a weather instrument called a barograph.
It has a rotating drum that records barometric pressure on a removable
chart. The charts are removed and replaced weekly. A specialized pen
is used to write to the chart.

My issue is that I only want to test it for a week because I want to
resell. It is supposed to use a slow drying ink, where a drop is added
to the triangular pen ink reservoir. However, for even small amounts of
this ink, the tiny bottles are running like $14, which was more than the
$10 (bargain) I paid for the device. It's called barograph ink, but as
I often know with things like this, giving it a special name causes
higher cost and there probably are other inks out there that are slow
drying that will work.

Your help on this would be appreciated.

Thanks in advance.

I have the same problem with my Wexler thermo humidigraph. This ink is
such a low volume item that it is expensive. The actual pens are
ridiculous.