Dear Stefan Trethan
it may have already been mentioned (my apologies if that is so!), but Edding permanent markers can be "reloaded", do not seem to dry out quickly and at least in black resisted all etchants that I have used. I used them years ago to touch up both foils for PCBs and final PCBs before etching. (though not for some years.)
I have only used black though for etching, I could not say if the other colors work as well in that respect, but they also do not dry out quickly as long as the cap is properly on....I have a set that I have had for at least 5 years of all the colors......they are still good though only used occasionally....all are reloadable if you buy the refill bottles....I have only reloaded black myself though.
They also come in several thicknesses too. Check here:-
http://www.waltersandwalters.co.uk/html/permanent_markers.html Regards
Andy
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The problem with the paint pens is that they don't keep so well. If
you are a hoarder like me you'll sooner rather than later be left with
a box of useless hard pens. That seems to happen much faster with the
"laquer" variety where you must pump the tip and hear a steel ball
inside when shaken, the permanent marker variety seems to store much
better.
One pen that works well on most etchants is the staedtler lumocolor
permanent marker. The red color is best (the ink is also used in the
marker for chemical lab glassware).
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http://www.staedtler.co.za/upload/318_2_420_16611.jpg>
It only resists strong etchants without fail if the pen is fairly
fresh, so it is best to get the refill station so you always have a
"new" pen at low cost.
ST
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