DIY Fluxes with ethanol-propanol-x-nol

Question

Got inrested in DIY fluxes by reply here.

1. Can you substitute rosin-core wire with DIY flux and non-rosin-core-wire?
2. How and where to actually use DIY fluxes if you have rosin-core wire?
3. Which % of ethanol and rosin should be used with SMD components?
4. Why to use a soldering flux? ( relates part 2)
5. With which substance you can avoid fungi? (relates to part 3)

Answer 1

Why have non-rosin core wire? Solder paste is flux with solder granules suspended in it.

You can use it on the surfaces beforehand or a drop on desoldering braid. Keeps things flowing :) Also, SMT.

I've usually seen propanol used as a solvent with resin. As little as possible to keep the active ingredient usably thin.

Answer 2

1. Please see XTL's answer.
2. The static user commented here: "There are times when addding additional rosin flux can be beneficial because is allows to solder to flow more readily with the less heating. For example when soldering connectors on coaxial cable."
3. Probably, it depends on the flux type. You can find instructions to do your own flux here.
4. Flux can be "non-corrosive, non-conductive, moisture and fungus resistant", according to the marketing of a rosin flux.
5. ?