Good Color Match Silver Solder for Brass

[davec2]

Several times in the past I have read posts asking about matching the color of brass with silver solder.  I recently came across a high temp high strength solder that did a wonderful job of matching color.  Not long ago I purchased a couple of sand cast trigger guards like this:





The castings were generally good, but the top corner of one was full of heavy porosity...too much to save it by filing back to good metal.  So I sawed off the corner, filed the cut flat,  and cut a small piece of the casting sprue to use as the new corner.  I used a yellow silver solder from Rio Grande (# 101-351) (http://www.riogrande.com/Product/Yellow-Silver-Strip-Solder-30-Ga/101351?pos=1)

Here is the finished guard:



Here is the front where the repair was made:



Here is where the joint is (you can't see it so I had to mark it with a grease pencil).



I thought it was a good enough match with the Rio solder to let whoever might be interested know.

[Jim Kibler]

Good stuff Dave.  Have you noticed whether they oxidize to a similar color as well?

[D. Taylor Sapergia]

Yes, that's the hard part.  I fabricated a guard for my Kuntz project using two guards to make one, and it consisted of five joints - all silver soldered together.  After filing, and polishing, the joints were invisible, but now, after several years of use, the joints are obvious, because the solder oxidized to a darker colour that the adjacent yellow brass.  I bought the solder from a local supplier and paid by the Troy ounce.  Seriously.
So, we'll be watching, Dave, to see how it changes over time.  Not that it matters one bit.  You've done a remarkable job on the fix, and oxidation is just going to happen naturally.  So what?

[SuperCracker]

What flux were you using?

[docone]

Batterns works well with that stuff.
I have found, fusing and using that solder makes less contrast on the joint. I reparied a CVA Jukar trigger guard that way.

[davec2]

Jim , Taylor;

So as not to make you guys wait 5 years for me to build something with the trigger guard and then wait for it to tarnish,  I sped up the process with a couple of brass darkening agents to see how the solder joint would fare.



The guard itself was colored with the "Historic House Parts Brass Darkening Solution" Jim uses for both brass and steel.  As the color developed, you could see the joint very well, but with a little more soak time the solder also colored dark.  So, in a natural tarnishing situation, I would expect the joint to show for a while and then, possibly, fade.

As another check, I tried three different solutions on the solder alloy itself, the "Historic House Parts" solution, Birchwood Casey "Brass Black", and Birchwood Casey "Super Blue".  As you can see in the photo, all seemed to color the solder itself very well.   The BC "Brass Black worked the quickest and darkest.

Shane T :  I'm not sure what solder flux I am using.  The label fell off the jar about 25 years ago...  It is, however, just a common water soluble, borax based flux.

[David Rase]

Dave,
For what its worth, you might consider fuming the repair area with ammonia fumes as another tarnish test.
Dave

[davec2]

Dave,

I will re-polish and give that a try as well.  Thanks

DC

[JCKelly]

You gentlemen might want to be cautious about ammonia. Given some amount of time, it will crack any brass that is under stress.

Castings are under stress as-cast, unless annealed (or stress relieved). Maybe this one got annealed/stress relieved during the soldering operation.

This cracking is something the Brits learnt about whilst bringing the Light of Civilization to India with .577 cartridge rifles. Daggone brass cases cracked every monsoon season. They started calling it "season cracking" They also stored there ammunition in the horse barns to keep it dry during all that rain. Nitrogenous vapors from horse products of metabilism have ammonia. I have an old British book on copper alloys. It warns not to store your automobile (which then had a lot of brass trim) in the horse barn.

[David Rase]

You gentlemen might want to be cautious about ammonia. Given some amount of time, it will crack any brass that is under stress.

Your statement is correct.  If you leave your brass in the fumes too long, you could see erosion, cracking etc.  I once fumed a set of sheetbrass hardware I made and actually had a crack erode between the edge of the patchbox finial and a screw hole.  Also had the front edge of an entry pipe erode and crumble away.  Reason being, I hung my brass in a 5 gallon bucket of ammonia for a couple of hours, decided it needed a bit more time.  Checked it a second time and decided if a little was good a lot would be better.  Forgot about the funing for another day and a half,  when I opened up the bucket I saw the erosion and crumbling on the patchbox and entry pipe.  A little fuming goes a long way.  Fortunately, the gun was an aged gun and the erosion and crumbling looked like it belonged on the gun. 
Dave

[chuck-ia]

Your work just amazes me. chuck

[sdilts]

Dave, what type of heat source did you use for the soldering?

[davec2]

Sdilts,

I have and use several different torches, but for this type of work I like to get the parts up to the melting temperature of the braze as quickly as I can.  The longer it takes to bring up the heat the more likely you are to have oxidation that will interfere with or completely stop the joining of the two parts.  For this, and many other things like casting gold and silver, I use a Prest-O-Lite torch.  It burns acetylene and air.  Here is what it looks like:

http://www.mcmaster.com/#gas-torches/=kap4h5  (click on the "Air/Acetylene Torch Kits" category)

You can sometimes find them on e-bay and at garage sales.  Mine is 60 years old, but I bought a spare not long ago and, unlike many other things, the new torch is EXACTLY like the old one.  Same materials, same quality, same interchangeable tips.

I also use one of these for much smaller work.

http://www.riogrande.com/Product/Basic-Smith-Little-Torch-All-Fuels-System-with-Five-Tips/500057?pos=1

The smallest tip is so small that I can weld two needles together crossed through the end paper of a recessed filter cigarette without burning the filter or the paper (if I work fast !)  I use this for hard soldering very fine gold chains that need to be repaired or altered.

I do also use a Victor oxy-acetylene rig and propane torches for other jobs.