I think the stuff that Kepro used to sell (and maybe still does) is ammonium peroxychlorate. I have found it to be much more benign, fume-wise and caustic-wise, than ferric chloride. You do, as I remember, have to use some mercuric chloride for a catalyst, which is a problem. I have found it to be much superior to FeCL2 for etching speed and have had a lot less undercutting problems. I made up a simple bubble etcher, which was the real secret to homebrewing PCBs. I seem to remember that heating FeCL2 made the best boards, but also the foulest fumes. The other stuff worked just fine cold. It has been a while since I made boards. It is a frightfully toxic business. One caveat for the homebrew board etchers: Copper ions are death to septic system bacteria. You are asking for big, expensive, trouble if you are on a private septic system and you dump spent etch down the drain. It is also highly immoral, if not illegal, to dump it into a city sewer system. Putting it out in the trash is also rude.... Dealing with the toxic waste is one of the more difficult problems with hobby-etching. Edward Gisske, P.E. Gisske Engineering 608-523-1900 gisske@offex.com ----- Original Message ----- From: "Gustaf J. Barkstrom" To: Sent: Sunday, February 29, 2004 8:45 AM Subject: Re: ] My first PCB production > Oyvind, > > It is ammonium perchlorate. Its fumes are nastier than ferric chloride > in my opinion. But, it does allow one to see the etching process through > the liquid, unlike ferric chloride. As always; ventilation, ventilation, > ventilation. Oh, and safety googles of course. Don't take your vision for > granted. :) > > Gustaf > > > > > What is the "Magic White powder" exactly? > > > > Oyvind > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu