# how is rosin flux soldering paste meant to be properly used?



## el_matt0

im referring to products like the one made by cardas, which come in a small plastic tub. i know that rosin flux is what makes the solder "flow", and with some specific types of solder that are slightly harder to work with, adding solder flux can help to get your joints etc to flow better. how are you meant to apply the flux properly though? do you place the iron tip into the tub of rosin and transfer to the joint, or use something to transfer some of the unmelted flux onto the joint FIRST....just a quick explanation on the stuff would help, ive never used it and am interested in seeing how it helps my DIY work! cheers


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## Kryosphinx

Usually, I use a tiny little brush for big work, and then a really thin toothpick for smd stuff. You just put the unmelted flux on the soldering spot and then solder like normal. It'll smoke and stuff, but it helps get the solder on and in the joint. 
 Try google.com There are tons of tutorials and stuff about basic soldering and such. Good luck!


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## holland

I just use a tiny screwdriver (jeweler's type) and smear the amount I need on...hmm, Crisco seems to come to mind for some strange reason.


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## pinkfloyd4ever

ya use a toothpick and just apply a little bit to the solder joint. With experience you'll get the hang of how much you need. Dipping your iron straight in the paste doesn't work; it just burns up most of the flux almost instantly and barely gets any on the joint (not all that much of an issue if you're using Kester paste since a tub of that will literally last most of us a lifetime) but I'm guessing if you have Cardas flux paste you paid way more than ~$4 for it.


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## tomb

The easiest thing is to dip the end of the solder into the paste. These days, this rosin flux is pretty hard, though, so use your iron to melt a bit first or thin it a little with alcohol (haven't tried that myself).

 In the old days, the Kester flux was more or less the consistency of a thick potato chip dip and it made this easier. Dip, solder, dip, solder - that was SOP.

 Obviously, it puts the flux exactly where it needs to go with no wasted effort.


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## Seaside

As tomb said, some rosin flux is pretty hard. 

 Kester rosin flux I bought is hard like a candle wax. It is hard to work with and smells funny when it burns. So I put it back to my part bin, and going back to the cheap Homedepot flux, which is soft, good to work with. 

 I am not sure if it is erosive or not, but it is ok for me since I clean the board after soldering is done.


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