Silver soldering High Wall extractor

I use Borax. You can buy it In the laundry detergent isle. Karl

Usually the same place you bought the filler will have the corresponding flux. Some fluxes have other stuff than borax in them, some fillers need that stuff to wick into the joint. So the real answer is that it depends. For that type of work, you can't beat silver braze/flux paste, expensive, but will give a good joint all the time without disturbing the clamped parts. Brownell's has it. Takes longer to purge the hoses on the O/A rig than to do the joint. A talc stick is also handy to keep the braze from wicking where you don't want it.

Stan

Is it going to be heat-treated after the brazing? If so, you'll need something high-temperature.