Is there any way around it? Maybe some kind of neutralizer? My problem is that I would really prefer to braze in lowrider mounts on an already built fork (rather than P-clips or other clamp on gadgets), but I don`t want the flux to eat up the metal and I can`t imagine much water would sneak in through the new bosses and the old vent holes. Another option I`m considering is some kind of "bolt through" boss, kind of like extra long chainring bolts and super-duty thread locker. For some reason, that sounds a bit iffy though. Any ideas?
Don't fight it, drill two holes (one at the bottom and one up top) for water/air to enter the fork so you can soak things properly. Use hot water and allow enough time to break down the flux. That's how the pro's do it so that's how you should do it.
If you're all freaky about sealing the holes you can stick a nail in the hole and silver it in place. You need to preheat or air will push out the silver.
Becareful buying/selling bike parts on-line. I learned the hard way. :(
Thanks for the responses. I`m not super worried about a couple extra holes, but I prefer not to drill more than necesarry. How big will they need to be? There`s already a little vent hole (~1mm) near the bottom of each leg and the bosses will have 5mm through threads. No problem with just that, or is another hole needed above the bosses? If so, how big?
Crap. I should have gone with my original plan (or Velonomad`s- that looked good too). Anyway, in the end I decided to weld because you don`t have to soak argon. It turns out I need more practice before I try TIGging thinwall tubing on important stuff. No craters or holes or huge heat zones, but it sure doesn`t look like the pros welds. The really stupid part is that I brazed bosses into another fork a couple years ago and they came out fine. But I never soaked the flux out of that fork and I know now that I blew it on that front. I do appreciate the advice, just wish I had stuck to it. Next time...