While the flame is, by definition, a
perfectly neutral mix, neither oxidizing or reducing,
you DO have control over it, somewhat, by which type of
solution you use in the vapor fluxing unit of the
torch. Each type of solution gives you a different
Pete, Could you elaborate on this? I thought I could only use the
flux that came with the uniy and use it as is.
You need to use SOMETHING in the fluxer, and only specific chemcials
will work. Use of the wrong materials can damage your torch, So I’d
not recommend experimenting too much with recipies. But different
solvents will produce different flame temps. My info comes not from
your unit, but from the Krohn ones, which of course operate the same,
and the Krohn instructions list several fluxing solutions. Here are
what Krohn recommends and sells, etc.
Their stock solution is a mix of methanol, acetone, and boric acid.
It produces a well fluxed flame usually giving pretty much oxide free
soldering, with a green flame color and a flame temp of around 3000 F
(1650 C). You can buy it premixed from them, or make it yourself.
The recipe consists of 800 ml methanol, 200 ml acetone, and 10 grams
reagent grade boric acid powder.
Methanol by itself can be used which produces a hotter flame with a
temp of around 4000 F (2250 C). Methanol is often the choice when
soldering platinum. This is not as highly fluxed a flame (without the
boric acid), so with other metals you may need additional
conventional flux on the work. Remember, additional flux goes ON THE
WORK, NOT IN THE VAPOR FLUXING UNIT. Fluxes such as Krohn K-flux,
or batterns, work fine.
46or lower temperatures, useful for working white metals, or
otherwise needing temps around 1300F (705 C), you use pure acetone
in the fluxing unit. As with the use of methanol, you’ll likely need
conventional flux on the work.
The Krohn instructions don’t list variations on these, but my own
curiosity would suggest trying the boric acid addition to the pure
solvents, as well as the mix, with ten grams boric to a liter of the
solvent. But try that at your own risk. I have no idea how well it
will, or will not, work.
And if it were me, I might also try, for the pure acetone mix,
adding five grams boric plus five grams borax. The reason is that
borax is more active at lower temperatures than boric acid, so the
vapor fluxing function might be improved at a lower temp range with a
bit of borax added. But I have no idea whether this would actually
work. Try it at your own risk…
Hope that helps.