> I just use a large plastic photographic tray & conc FeCl3. Rock it gently
> back & forth by hand - takes ~40 minutes @ room temp. Wear rubber
> gloves! Debbie.

Debbie, I'm not a big fan of long cold etch times, mostly because the
etchant
has time to get under etch-resist and make breaks or fuzzy tracks

The simplest fix is a hot water jacket. Etch time will be 6-7 minutes

http://home.clear.net.nz/pages/joecolquitt/0makepcb.html

Also, float the board upside-down and you won't need to rock it either
(you'd not considered a little motor to do the rocking ?). Better if you do
this with GRP stock as you can see the tracks form. Not so easy to see
through phenolic unless you have illumination from below. Every now
and then decant cold etchant and run it through a filter. Paper is OK, eg
coffee filter, kitchen towel

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