Homebrew PCBs

Hi,<br><br>First post, hopefully one of many..<br><br>To cut a long
story short, I'm having problems <b>after</b> etching with Sodium
Persulphate in my very old RS etch tank ( purchased from ebay many years
ago ). The etch tank has a working agitator which I've been
using.<br><br>The press-n-peel blue transfer ( Laserjet 4 ) to the 1.6mm
single sided copper board, via the laminator, appears to be pretty close
to spot on ( sometimes the lines are a little blurred, which I'm
guessing is due to too many passes ). <br><br>Issues:<br><blockquote>1.
Etching is taking a bit longer than I expect ( ~15 minutes ). The very
first couple of etches I did took < 5 minutes. Since then it's been
getting progressively worse. Assumption was that the etchant was getting
worn ( used 5 or 6 times ). So yesterday I cleared out the etchant,
mixed some fresh 2.5 litres with 500g of etchant and had another go.
Same, about 15 minutes.<br><br>2. The result looks pretty good ( post
etch ) with the toner still visible. If you check under a magnifying
glass you can see all the tracks in tact, nice clear and strong. I clear
the toner off with a little thinners and the end result is just plain
awful. A lot of copper tracks are etched straight through, most are very
thin thin indeed and pads look massacred, even though the toner above it
looked spot on. In short, it appears to be etching <b>under</b> the
toner somehow.<br></blockquote><br>My guess is that the etch tank is no
longer getting to the right temperature ( ~ 45 degrees ) and I'm etching
too long with the agitator on. I'm going to get myself a temperature
probe to confirm.<br><br>Has anyone had a similar experience ( Etch
looking fine until the toner is removed )?<br><br>Thanks in
advance,<br>Phil.<br>