RADBMX.CO.UK
Technical & Reference Section => Tech and Restoration => Topic started by: griff on April 06, 2015, 01:28 AM
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Anyone got any info?
Looking to keep a F&F raw so brazing can be seen, also would be nice if those lovely heat markings could stay too.. Is it possible? If so what's the magic technique?
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A quick look round the net suggests it would be handy to know which flux was used. It seems high temp stuff, which I imagine is the one used for bikes, needs hydrochloric acid diluted in water
"The only time you run into trouble removing flux is when you haven't used enough of it to begin with, or you've overheated the parts during the brazing process. Then the flux becomes totally saturated with oxides, usually turning green or black. In this case, the flux has to be removed by a mild acid solution. A 25% hydrochloric acid bath (heated to 140- 160°F/60-70°C) will usually dissolve the most stubborn flux residues. Simply agitate the brazed assembly in this solution for 30 seconds to 2 minutes. No need to brush. A word of caution, however - acid solutions are potent, so when quenching hot brazed assemblies in an acid bath, be sure to wear a face shield and gloves."
Not found any articles that say if it will affect the heat markings though.
I imagine Mr Curtis mayknow ;)
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You could try a small amount of limescale remover, it contains the same as above but is weaker Just to see, I would brush on a very small area of flux with a bit of Viakal just to see if it reacts with the flux :daumenhoch: if it works then rinse, get a bucket of clean water, submerge the area of frame in the water and add a tea spoon of bicarbonate soda (cooking soda) to neutralise it, rinse then dry
In controlled factory conditions after being dipped in any acid solution it would then be rinsed with water then dipped into another tank to neutralise it and rinsed again otherwise it could continue to damage the frame in time.
Not one for the kitchen sink !
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Just had a big barrel of battery acid turn up at work today :shocked:
Bet that'll shift it mrs :teef:
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Thanks for the replies chaps :daumenhoch:
I'm not planning to attempt this at home! Will try & find out what kind of flux Brian uses and work from there