Solder/flux debate

[Brett Duggan]

Hi DIYers,

Thanks to all who mentioned the kind words about posting questions about 
synth repair.  I will bring up that situation in the near future.  :)

As for now, I just wanted to address an issue regarding solder and what 
kind is recommended for synth-DIY matters.

Kester has four kinds.  The descriptions included in quotes are snippets 
of the descriptions in the Mouser catalog:

44 Rosin Core - "The flux residue is non-conductive and non-corrosive."

285 Rosin Core (Mildly Activated) "It is less corrosive and conductive 
than 44 rosin and is commonly used without subsequent flux removal."

331 Water Soluble Core - "It is more effective and heat stable than rosin 
fluxes in soldering difficult metals.  Soldering with 331 should always 
be followed with a water wash to remove the residues which are conductive 
and can absorb moisture."

245 No-Clean Core - "The residues left from 245 are designed to be left 
on with no post soldering cleaning."

Okay, now...based on these descriptions, it seems to me that the best to 
use for synth-DIYing would be either 285 or 245.  So why is it that so 
many of you guys recommend the 331 water-soluble kind?  It seems to me 
that the 331 would be the most troublesome, due to always having to clean 
it.  Or in this case are we "soldering difficult metals"?  Or is it that 
you guys just take issue with the truthfulness to the statement that 
rosin flux "is non-conductive and non-corrosive"?  And if no-clean solder 
is not supposed to be cleaned, then what the heck kind of flux does it 
use?!?!

Thanks very much for any opinions!  I can't wait to read the replies on 
this one.  :)

Brett D