Homebrew PCBs

P.O. wrote:
> 
> Does anyone use sodium persulfate as etchant?
> I'm makeing my first pcb using toner transfer from kodak-paper. But the 
> etchant doesn't work very well.
> I use about 0,8 dl etchant for 4 dl of water@ca 50\ufffd in a plastic bowl 
> that and moved stirred it pretty much the first hour... The pcb is 
> about 4x3 cm big.
> Now it has been in the etchant all night and only about 1/8 of the 
> board has etched.
> Maybe the kodak-paper left something on the surface? I did iron it 
> about 60 seconds on both sides. To long?
> 

0.8 dl  would be 0.8 deciliters =  0.08 liters = 80 milliliters
Is that correct ?

Normal makeup concentration of ammonium persulfate etchant is 100 to 200 
g/L and should be heated > 35\ufffdC for reasonable etching times. A fresh 
solution at 65\ufffdC in a bubble etching tank will etch 36um thick foil PCB 
material around 5 to 8 minutes. Sodium persulfate and ammonium 
persulfate are practically interchangeable.

If the copper looses it's shine in first 30 seconds then the etchant is 
working. Is that happening ?