> > I don't plan on using ferric chloride. That leaves, as I understand
> > it, sodium persulphate and ammonium persulphate. Are both these going
> > to work OK with the Sharpie I plan to use for touch-up?
> I do not use the "sharpie" because it is not sold here.
> i use Steadtler red ink ohp pens. the red is best af all staedtler
colors
> for resist.
I tested a bunch of markers on an etch in Ferric Chloride. I didn't
heat the ferric chloride enough, I guess, as it took half an hour.
I made several lines in bare patches on the boards with each marker.
Everything but the sharpie and Staedler Lumocolor 313 (red)
dissappeared within minutes.
The Sharpie started failing in the thinner areas. By the time etching
was done, thinner Sharpie lines were completely etched, all Sharpie
lines were considerably narrower and some wider areas had partly
etched spaces.
The Staedler 313 lines were perfect. I did not specifically measure
them before and after, but the widths seemed the same, even the very
narrow lines were still there.
Other people have even tested different colors of Staedler Lumocolor
and found red to work best. I'm not sure if you can still get it as a
refill ink in order to load it into an inkjet printer or an empty
plotter pen.
Steve