removing flux residue

I am using a silver solder paste that contains potassium difluorodihydroxyborate as flux. What is the best way to remove any residue of the flux after soldering? As the ring will most likely be worn 24/7 (i.e. also during food preparation and things like that), I want to avoid the possibility of any flux remaining on it. I usually pickle my rings after soldering in a vinegar and salt solution and afterwards I brush/polish them thoroughly with a metal brush under running water. Is that enough to make sure the ring is flux-residue-free?

Try your usual pickle first. If unwanted residues still remain,m then use safety pickle followed by a hot bicarbonate of soda solution, and then rinse in plain water.. Dennis.

Thanks, is it always possible to see the residue with the naked eye?

Once I've gone through the routine it's good enough for me.

That said I don't use fluxes that leave a hard to dissolve glaze behind.
For me paste solders are messy, so I use snips of strip solder with Auflux (a yellow liquid applied with a brush}, which requires much less work to clean up afterwards. Dennis.

How have you found the safety of Auflux? Inhalation? I've been using borax cause as far as I know it's really safe. But I've been having problems removing it completely with alum pickle. I've been contemplating changing my pickle.

I've always used Alum pickle and if it doesn't remove the residue, just leave the piece in for longer and add some more alum crystals to the water. I hardly use Auflux any more, as I find the solder doesn't run all the way through the piece, whereas it does with borax.

All these different opinions are the whole point of the forum of course.
Auflux has been my go to, even for large pieces like belt buckles, but it does get exhausted more quickly than borax. So it will not allow extended periods of heating.
Safety pickle in a lidded slow cooker does not give off any noticeable fumes, nor do nearby tools get rusty, or corroded.
Dennis.