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Black Grungy Stuff In My Soldered Projects?

Dirty solder messy grungy

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#1 Pineapple24



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Posted 02 August 2017 - 08:42 PM

Hello all! 


I started this hobby a couple months ago and it seams that on all of my projects there is a black grungy substance in my solder. It won't wash off. I even clean my tip constantly while working. A professional told me it could be my flux. Possibly using too much? Or maybe its contaminated? Can I get some opinions?

#2 Marilyn



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Posted 02 August 2017 - 09:01 PM

What type of solder are you using? One reason for this may be that the solder being used is not pure. Inexpensive solder sometimes leaves residue. Sometime you can clean the particles out but it is easier to buy quality solder to begin with.  Another reason is that spots are often caused by dirt or other particles caught in the solder. These can often be removed when you wash or buff your piece when it's finished.


You should not dip your flux brush in the bottle the flux comes in. Constantly rubbing the foil with the brush and dipping the brush back in the bottle contaminates the flux and causes all sorts of soldering problems.

Get a new bottle of flux. When you're ready to solder, pour a small amount (like a tablespoon) into another container. Use the flux out of there. When you're done soldering, dispose of the remaining flux in that container. The flux in the original bottle will remain fresh and uncontaminated.

Wet a paper towel and squeeze it out so it is only damp, not soaking wet. Fold the towel into a square. As you're soldering, frequently wipe your soldering iron tip on the towel. That will keep your tip clean.


An excellent source for solder which is American-made, free shipping, and excellent customer service is <http://www.ebay.com/...er/172783866711>  Make sure it is coming from Hutchins, Texas.


I hope you have better luck on your next project.



#3 Pineapple24



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Posted 02 August 2017 - 09:46 PM

Thank you Marilyn! 


I'm going to buy some new flux as I haven't been doing any of the steps to keep it from getting contaminated. Hopefully this fixes the issue! Also, I use 60/40 solder. I got it in a beginner's kit so I'm not sure what brand it is, if that even matters. 

#4 Tod Beall

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Posted 03 August 2017 - 08:15 AM

Marilyn's reply is spot-on in my opinion.

Keeping the tip clean is very important and should help keep the solder line cleaner.


0000 steel wool can help clean up after the fact.  - Tod

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