flashlight bore cleaning rod

[Ricklesss]

Yes, that's where I get it as well, its cheap, too!
So, I do a fair bit of soldering on motorcycles, but I don't know how or when one would use the citric acid.
Is this a technique I should learn?
I'm pretty good at soldering now, but always interested in learning.
Thanks!
Ricklesss

[mklotz]

Yes, that's where I get it as well, its cheap, too!
So, I do a fair bit of soldering on motorcycles, but I don't know how or when one would use the citric acid.
Is this a technique I should learn?
I'm pretty good at soldering now, but always interested in learning.
Thanks!
Ricklesss

Just to be clear, I'm referring to silver soldering, not soft soldering. The solder used to secure electrical joins is soft solder and, while there is some flux residue, it's seldom removed except in the case of circuit boards.

Silver soldering (really closer to brazing than soldering) uses silver-bearing solder to form a much stronger joint. The temperatures required are far higher than those of soft soldering. A difficult-to-remove residue results from the process and should be removed both for appearance sake and to prevent corrosion.

In model steam engine building, silver soldering dominates but soft, low silver bearing, solder is used occasionally such as a joint sealant for rivetted boilers.

[Ricklesss]

Ahhhhh, that totally explains it!
Thanks!
Ricklesss

[Mononeuron]

Citric acid has the wonderful property of being more reactive in diluted form over a concentrated form. If you want it to be a stronger more active reaction you actually water it down but in the concentrated form it is a lot less reactive. Learned that in chemistry class 30 years ago but never actually tried it.
I also read in a hobby magazine years ago that you can soft solder Aluminium if you put a few drops of light oil on the surface and then scratch it clean with a small screwdriver and the oil stops the Al from oxidising, you then apply a bead of soft solder while the oil is still on the part. Never tried it but it does sound logical.
Rich.

[Moby Duck]

Citric acid has the wonderful property of being more reactive in diluted form over a concentrated form. If you want it to be a stronger more active reaction you actually water it down but in the concentrated form it is a lot less reactive. Learned that in chemistry class 30 years ago but never actually tried it.
I also read in a hobby magazine years ago that you can soft solder Aluminium if you put a few drops of light oil on the surface and then scratch it clean with a small screwdriver and the oil stops the Al from oxidising, you then apply a bead of soft solder while the oil is still on the part. Never tried it but it does sound logical.
Rich.

Oil as a flux always sounds illogical to me, but I do know that the recommended flux for soldering Pewter is Olive Oil. Of course old Pewter plates and mugs had a high lead content which is why they shouldn't be used today. Newer manufactured Pewter is supposedly close to 100% pure Tin. I am not sure which Pewter type the Olive Oil is best suited for.

[Mononeuron]

I guess the oil part does sound illogical but the exclusion of air was the logical part I was thinking of as Al instantly oxidises in air. I will have to try it soon and see what turns up. I may just make a lot of beads of soft solder or it may work. Olive oil may have been the type of oil the person who wrote about this was talking about. Maybe a test of a few different types would be in order and maybe heat from underneath the plate and not directly in the oil itself.

[Ricklesss]

Had no idea about weaker solutions of citric acid working better then stronger concentrations.
I really do wish I had paid more attention in chemistry class rather then flirting with Brenda...
I will water it down and experiment a little.
For rust removal, I generally use about oz. of citric acid by volume, to about a quart of water. Or so.
Works very well. Was keeping it warm on an electric radiator as well, it really bubbles!
Ricklesss

[Frank S]

I've never tried to solder aluminum, I've just mig, tig, stick or welded with an oxygen acetylene torch and for those processes the operative word is CLEAN ,clean and clean some more.For mig and tig the use if a pure inert gas such as Argon of Helium is required for stick the electrodes are flux coated. after cleaning of the weld can be a bother I normally use a rotary SS wire wheel. For torch welding I use the stick electrodes and a low neutral flame slightly on the yellow side towards carborizing.
The HVAC guys routinely solder Aluminum to copper but I've never tried it so can not explain their process.
When I was a kid an Uncle of mine explained how he as he called it welded pewter buy making welding sticks out of doner pewter buy melting it down then removing one side of a piece of corrugated cardboard to make sticks somewhere along the way he used a judicial amount of a paste he made out of oxalic acid and wax he made form honey comp other than that I do not remember much. I watched him do it a few times but was too young to try it for myself I do know that he could mend a broken pewter heirloom so it looked like it had never been repaired