In message <9B73ACC8-0379-11D9-AADA-000A95E5DF26@mac.com> William "Chops" Westfield wrote: > Lye is seriously DANGEROUS stuff. And yet it's used as a PCB developer in some cases... Hm. > Adding the copper from a couple square feet of boards (at about 1oz/sw > foot) isn't a big deal. Well, there's an outside drain that the guttering runs into. I suppose the old "chuck it in a bucket, heavily dilute and dump down the drain" trick might work... ISTR Radioshack actually printed that on the side of the bottles of etchant they sold, but I wouldn't take their word for anything. The other suggestion I got was to chuck the FeCl into an ice-cream tub, add some Plaster of Paris, then cover the tub, put it in a bag and leave it to set. I suspect PoP is alkaline, so it would theoretically neutralise the FeCl+HCl, %DEITY knows what byproducts it would produce though (probably CO2). > If you feel you must neutralize your spent etchant, sodium carbonate > ("washing soda") should work just as well as Lye, with considerably > less danger to the > users and families thereof. OK, I'll try and get some of that then - time to find a pool supply store that stocks the stuff. Last time I looked, most of the stuff at the local supermarket was full of various additives... > pH paper shouldn't be necessary. Add carbonate (or hydroxide) until > percipitation stops, and then maybe add a bit more. Both are common > cleaning agents and a bit extra will hurt things even less than the > copper. Thanks. -- Phil. | Acorn Risc PC600 Mk3, SA202, 64MB, 6GB, philpem@dsl.pipex.com | ViewFinder, 10BaseT Ethernet, 2-slice, http://www.philpem.dsl.pipex.com/ | 48xCD, ARCINv6c IDE, SCSI .... President/VicePresident is undefined. Cannot divide by zero. _______________________________________________ http://www.piclist.com View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist