In article , 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.

J-J-

What about rubber stamp ink? You buy it in a small bottle that is
corked by some kind of sponge, and smear it on the stamp pad. It does
not seem to dry on the pad, but soaks into the paper that is stamped.

I think the price is in the $5 range, but you might already have some.

Fred