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.
food coloring in a glycerine base?

The following formula is recommended :

Aniline colour . . 10 gm. Glycerine 125 cc

Sugar . . 10 gm. Water . . . . 250 cc

Heat the water and dissolve the sugar in it ; add the glycerine in
small quantities
and stir the mixture thoroughly until each added portion is dissolved.
Beat up the
aniline colour in a small quantity of the mixture and stir into the
remainder of the
mixture. The ink is ready for use when cool. Various dyes can be used,
giving
different coloured inks.

This normal type of recording ink can be used at ambient temperatures
down to about 5° F. in the normal triangular pen, or to about —30° F.
in a pen of the crow-quill or tit-quill type, A special ink having
the composition, water 50 cc , ethylene glycol 50 cc , methyl violet 2
cc , can be used at temperatures down to about -50' F. with the
triangular pen or -75 °F. w ith the crow-quill or til-quill pens . .