Thanks for your responses everyone, I had started to realise that it was possible to clean up and area by running the torch back over it, but it's always nice to get confirmation one is doing the right thing.
Doug! You might not remember me - I was trying to get started with a framebuilding project about 6 years ago (can't believe it was that long), and you took the time to answer many of my questions. I think we got in touch via the framebuilders list. You were about to embark on an overseas framebuilding project - I think you wanted to teach communities to build practical bicycles for everyday use.
My job, moving house, getting married etc. sort of took over though, and it was proving too difficult to get hold of gases for the brazing torch and the project came to an end. But I have recently seen some videos of people using mapp gas to braze with silver, and my enthusiasm has been renewed! It also helps that I have a cellar with a workshop, so have the space to work in now. I bought a turbo torch that I've discovered is plenty hot enough for brass as well as silver and the map pro gas is freely available from the local hardware superstore (and it doesn't void my house insurance!). Some people say it's not quite as good as oxy acetylene, but it's all I can access for the time being.
I still have copies of the emails you sent, and I'll be looking them out as I progress. I had been planning to get in touch with you just to say thanks again for the advice you gave me all those years ago - it was not wasted. You were very generous with your knowledge
Your description of how to flow the silver neatly around the lug was very helpful, especially the idea of having a dumping ground to collect to the excess. I'm going to keep practicing, but will hopefully be moving on to my first frame (a compact lugged road frame) soon. I have been achieving some nice results with small fillets of silver when brazing bits of scrap stays to larger diameter tubing. I'm hoping this will pay off when I come to brazing the seat stays to the seat lug on the frame.
I'd like to produce a photo diary of the build to post here, as others have done.
Cheers, Ewan (Manchester, UK)