On Wednesday 26 December 2007, Dave Engvall wrote: >Hi Jon, > >Riston sounds like better stuff and easier to use. I think one gets >sharper etching if the etchant is pumped over the foil.
Many years ago, we had a DEA spray etcher at the tv station where I got started back in the early 60's. You could write notes in the 10x10 boxes of the gfx background we used to do our layouts on, and which got reduced 4x before the board was exposed. With that etcher, it was a 3 to 5 minute job as it sprayed both sides of the board at the same time, and you could still read the notes very clearly in the copper when done. I have never rocked a pyrex cake pan and got anywhere near that sort of precision results since. >I guess I'm pretty casual about solvents having worked with benzene >above the permissible limit for several weeks each year. Anytime you >can smell benzene you are above the 8 hour limit. We used benzene for >an extractant in the analysis of alpha and beta acids in hops (the >bittering component). After years of using benzene the procedure >changed to toluene which is about 10 times less toxic. If these and >other chemicals were as dangerous as some people think I would have >been dead long ago. I think I'm still here. ;-) I know the feeling, Dave. I have litterally swam in both pcb's and 2-4-t's of various formulations back in the 50's through the later 70's. Now 73, with sugar, and that seems to be the major effect, all that other stuff is a question to me. About the only thing I've tried to steer clear of is methyl chloride since it can write a fini to your liver & kidneys if abused. >Dave > >On Dec 25, 2007, at 9:22 PM, Jon Elson wrote: >> Kirk Wallace wrote: >>> KPR? >>> >>> Kentucky Paranormal Research >>> Kawartha Pine Ridge District Public School Board >> >> Kodak Photo Resist, a Xylene-based organic photo resist that is >> hardened by exposure to UV light. It is very "old school" and >> not only requires nasty chemicals, but is quite fragile. The >> aqueous-based developer for Riston photo resist is washing soda, >> and the stripper is a weak lye solution, I get both on my hands >> without harm. >> >> Jon >> >> ---------------------------------------------------------------------- >> --- >> This SF.net email is sponsored by: Microsoft >> Defy all challenges. Microsoft(R) Visual Studio 2005. >> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users > >------------------------------------------------------------------------- >This SF.net email is sponsored by: Microsoft >Defy all challenges. Microsoft(R) Visual Studio 2005. >http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ >_______________________________________________ >Emc-users mailing list >Emc-users@lists.sourceforge.net >https://lists.sourceforge.net/lists/listinfo/emc-users -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) When you say that you agree to a thing in principle, you mean that you have not the slightest intention of carrying it out in practice. -- Otto Von Bismarck ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
