Flux - you learn something new every day

[mmagliaro]

... no matter how the "something new" is.

This is just supposed to be a "happy" post.

I have never used flux in my life for soldering.  I think I have a good handle on the basic technique of soldering, and my joints
are clean, bright, and neat.  But when I soldered the magnet wires to that little SMD LED for my 4-6-2 project, I figured I better
follow the conventional process that everyone talks about, so I bought some of that gel paste flux at Radio Shack.

Wow.   Yep.  You put a drop of that stuff in there before applying the iron, and the solder just flows INSTANTLY.  I could make
much quicker joints with much less solder.

You should still have a clean, tinned iron, clean surfaces, and good technique.   But flux is mighty helpful.  Better late than never that
I tried it, I suppose.

[davefoxx]

Yes, flux is good stuff.  I also find that the solder only tends to go where the flux is, which is helpful when you're soldering in small places, like the pads on a decoder.

DFF

[mmagliaro]

Yes, flux is good stuff.  I also find that the solder only tends to go where the flux is, which is helpful when you're soldering in small places, like the pads on a decoder.

DFF

YES!  I was soldering a fine phosphor bronze wire to a brass plate, and the solder flowed and stuck in a little tinned spot
only where the dot of flux was.  The whole joint is miniscule compared to what it would have been if I didn't use the flux.
It still would have been neat and flat, but I would have had a much larger pad of solder on the plate where I soldered the wire.

This will be great when I solder my brass cooling line hangers to the brass walkways on my loco project.  Just a dot of solder right
where the joint is.

Another reason I started this thread is that I suspect there is more than one "old hand" out there like me who has soldered
for years without flux and doesn't know what they are missing.  Perhaps a dedicated "YOU SHOULD TRY THIS STUFF" thread
will get them to give it a go.

[spookshow]

"Noted Electronics Guru Max Magliaro Discovers Flux!". The least likely headline of 2013?? 

Cheers,
-Mark

[Denver Road Doug]

Same here...I soldered for YEARS and never used it....never "got it" what it really did.    I can't even remember why but someone pointed me to the liquid flux they sell at Fry's (can't remember the name off the top of my head) and it just makes the process so much easier.

That and Xuron cutters for flextrack are the two things I wish I'd known when I was a kid building model railroads.

[engineshop]

Flux does not only make the solder flow nicer but also faster. This is the key to the tiny LEDs that cannot take too much heat over a long period of time (talking about seconds). I use high heat to solder 0402 SMD LEDs but only touch the LED and wire with the solder iron for half a second or less. Without the right flux, it won't work.

[VonRyan]

How do you tin the iron? Every time I apply solder to the tip of the iron, it just beads up and runs away...


-Cody F.

[mmagliaro]

How do you tin the iron? Every time I apply solder to the tip of the iron, it just beads up and runs away...


-Cody F.

If that is happening, your tip is probably dirty.

Another MUST... you need to have a clean wet sponge!   (Another thing I didn't know when I started soldering
as a teenager 100 million years ago).   Keep wiping that hot iron on a wet sponge and get it as clean as you can before
you try to apply any solder for tinning.
You may find, if the tip is all covered with dark, burned junk, that you can only get the solder to stick on
one or two spots.  Do it.  Then wipe on the wet sponge and repeat, until you get rid of all burn junk and get a completely
clean, silver, solder-coated tip.


If you've never cleaned the tip and never tinned it, it is probably all dark and cruddy.
 If it is just a plain copper or copper alloy tip, then carefully sand off that junk with some
very very fine sandpaper (like 220 or even finer... you don't want to be rasping on it with coarse stuff).
When you see clean shiney metal, your solder should stick to it.   

But again, apply a little solder, then wipe it on the sponge.

DO NOT USE SANDPAPER if you have an iron-clad, or other "long life" tip.  The iron cladding will be sanded off and the tip
will be ruined.

Speaking of which.... if you can get the iron clad or "long life" tips for your iron, go to the store right now
and buy one.    It makes soldering so much easier.   Plain copper tips, the kind that come in most cheap blister-pack
soldering irons, get dirty and cruddy fast and are hard to keep clean and tinned.

[Dave Schneider]

How do you tin the iron? Every time I apply solder to the tip of the iron, it just beads up and runs away...


-Cody F.

A tinning compound also works very well.
http://www.ebay.com/itm/Techspray-Plato-TT-95-Tip-Tinner-Lead-Free-No-Residue-/261166360013#vi-content

Best wishes, Dave

[GaryHinshaw]

Better living through Chemistry.  Just don't forget to clean the flux residue with a suitable solvent.

[Alwyn Cutmore]

This is an article I wrote back in 1989 which deals mainly with soldering white metal locomotive kits. The principles for all soldering are basically the same and it will give you a good idea why we use flux and how it all works. I have been soldering white metal kits to-gether now for years and it is virtually second nature to me when I am soldering.

http://www.arkits.com/articles/The_Art_of_Low_Melt_Soldering_modified.pdf

Regards

Al

[jereising]

I was a BIG Heathkit fan from high school days until they closed up shop.

And I never used flux because there was no need to, everything was pre-tinned. 

And I used rosin core solder (still do).

But later in life when I got into some non-tinned joints, I tried this "flux" I'd read about.

And much like Max, it was an "AHA" moment.

My flux is always handy.  There are times you simply need it.

And the rosin core simply isn't enough.

[Philip H]

Heathkit was my introduction to electronics.  Wish I still had all the things I built over the years.  And I too have never used anything but rosen core solder - though I do have some metal worksing silver based solder for some of my non-hobby applications.

I just wish I could find a local vendor for Superflux.

[Sokramiketes]

This will be great when I solder my brass cooling line hangers to the brass walkways on my loco project.  Just a dot of solder right
where the joint is.

Maybe you know this, maybe not.  But now that you're using flux separate from solder, you can apply the flux to the model, pick up a sliver of solder on your iron, and touch the joint.  By sliver, I mean physically chop up some solder into little chunks and pick them up with the iron as you need them.  This keeps you from going overboard with a spool of solder trying to feed the solder into a joint... fine for electronics, not fine for small n scale brass details. 

[engineshop]

Also a bunch of replacement tips in different shapes should be a part of your mistery box.