soldering problems

[VARIVERRAT]

i been using the same solder since i started building. its acid core metal working lead free silver solder frome home depot but latly the roll i bought has had a black oil secreting from it when it melts. the surfaces are beyond clean and the temp is right. ive never had this problem before. any advice?

[Ayay]

Cored lead free silver solder is mostly pure tin with about 3% silver (or copper). Should really be called tin solder.

Cored solder has resin flux which is not very active and is used for electronics because the flux is not corrosive and can be left there afterwards. I can't answer why the flux inside your cored solder turned black. Does it still work?

If not then the solder can be rescued by melting it in an iron pot and pouring into the 'V' of a piece of angle iron to get a clean bar. Buy a bottle of 'Bakers Fluid'/'Killed Spirits'/'Zinc Chloride'. This is the flux that plumbers use for lead or tin/lead solder and it works just as well with pure tin. It's an active flux that corrodes metal if not washed off afterwards, thus it cannot be used when soldering electronics.

If you buy a new roll of tin 'silver' solder, get the non-cored variety and a bottle of Bakers Fluid. This will work much better than the resin flux found in cored solder.

[Kentucky shinner]

Get you a roll of lead free solid solder and a bottle of Harris stay clean flux. You can get the flux from most any plumbing supply store. I think you will find this will take care of your problems.
KS

[VARIVERRAT]

thanks guys

[Kentucky shinner]

Hint. If you will carefully apply the flux to only the area you want to solder, that is the only place the solder will flow if you are very careful. It will make a very nice solder join.