In the past I've had to do some repairs on some of my hand-laid turnouts...mainly PCB throwbars coming delaminated after re-soldering them dozens of times....and I haven't neutralized any of my solder joints on those in-place repairs because of the paint, ballast & scenery. ALL of my track soldering is done using Superior No.30 Supersafe Soldering Flux, and I've never had any visible oxidation happen on any of my repairs, no paint bubbling, no weakening of solder joints. This leads me to think that the heat neutralization actually works as advertised.
The whole reason I started my search for the very best soldering flux for non-electrical structural applications was my disastrous experience using "Plumber's Honey" to construct my first Code70 N-scale turnouts that I used on my first two Ntrak modules. Oh yeah, it made construction really easy and quick, but after a year, the oxidation was very evident visually and after two years, it had started eating my ballast, my track paint, and then the solder joints started failing.
About that same time, I noticed a fellow who was selling N-scale catenary at a local train show, building his catenary behind the counter...and I started asking him questions about his soldering techniques, relating my bad experience. He put me on to the Superior No. 30 Supersafe Soldering Flux and using 96/4 Tin/Silver solder...and he just happened to be selling both of 'em at the show, packaged with H&N Electronics on the labels. I bought both and I went home that evening and built a couple of Code70 #8 turnouts to start replacing the ones that were disintegrating on my modules, and I've never looked back.
Sooo...as far as I am concerned, there is no debate...Superior No.30 Supersafe Soldering Flux is THE BEST soldering flux for model railroad structures and track, and 96/4 Silver bearing solder is the best solder to use for structural work and for solder joints you need to be robust...such as track feeders. I literally threw away all my other fluxes (except my copper pipe plumbing flux)...and use my Supersafe for all my soldering...with solid core solders.
'Nuff said.
Cheerio!
Bob Gilmore
