I am a complete noob when it comes to soldering. I've only done a little bit in the past and it was years ago. Today, I bit the bullet after reading about how to solder and purchased some soldering supplies a the local Frys. When I got home I read the label for the paste flux I purchased and it said:

Kester Self-cleaning Acid Paste Flux Formula SP-30

I didn't see anything that said rosin, so I went online and read the manufacturers datasheet. It says:

Like other inorganic acid fluxes, Kester SP-30 is too corrosive for electrical or electronics soldering applications. In all cases, the flux residue should be removed after soldering to avoid any corrosion problem.

Did I just buy plumber's flux instead of electronics flux? Does this product have any utility in electronics? If not, why would Frys put something like this in the electronics soldering isle?

  • \$\begingroup\$ Will just post as a comment because I'm not sure, but it sounds that way to me as well and will be useless for electronics. Are you soldering anything difficult? I've rarely used flux seperately and just use flux-core solder. \$\endgroup\$
    – PeterJ
    Mar 10, 2013 at 5:01
  • \$\begingroup\$ My brother soldered up his home brew stereo amplifier with acid flux... boy, did he regret it! It didn't take long for all the joints to corrode. \$\endgroup\$ Mar 10, 2013 at 5:10
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    \$\begingroup\$ @PeterJ, I bought it just in case something difficult arises. Don't you hate not having what you need when you need it? Can this be used to at least clean soldering iron tips? \$\endgroup\$
    – user148298
    Mar 10, 2013 at 5:24
  • \$\begingroup\$ @user148298, fair enough, when you described yourself as a soldering noob I thought you might have thought it was needed often. Personally I wouldn't use it on tips when it's corrosive, probably will do more harm than good. \$\endgroup\$
    – PeterJ
    Mar 10, 2013 at 5:39

1 Answer 1


Yes, if it's an acid flux, you can't use it with electronics like they say. Definitely sounds like plumber's flux. I would return it to Frys.


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