Ink Supply mentions us (via the Massmind site and the Inkjet_PCB_Construction yahoogroup) on the page for the specific yellow pigmented ink that works well.
Not sure if anyone has tried putting this ink into a plotter pen.
Steven Greenfield AE7HD
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Re: [Homebrew_PCBs] HP technical pen ink does not work for etching
2016-11-22 by alienrelics@...