Hello

I am a hobby frame builder and am currently working on my fourth frame. I always braze in two passes: First a basic seam of nickel-silver and then the fillet of bronze or 20% silver.
It works well so far, but I stress the tubes by applying high temperatures twice.
Hence my question: Do I need the first pass at all? Or is it enough to braze once, but then with bronze? How do you do it?

The materials I use:
From https://www.sonderlote.de/
Fontargen AF210, A102 and A303

Best regards,
Christoph