Silver solder flux ruins blue

[choppero]

Does any one have a method to prevent the flux from effecting the blue when soldering a front sight?

 

[rcmodel]

I sure don't.

For flux to do it's job, it must remove everything clear down to bare metal or the silver solder won't stick.

I use a lead pencil or soap stone to keep the solder itself from sticking where I don't want it to stick.
But the flux itself, I haven't found a answer for.

rc

 

[jaguarxk120]

Flux does what it is suposed to do, remove oxides from the metal so the solider can bond to the surface.

Some fluxes will remove the blue from the surface as the blue is a oxide of the steel.

You may have to use a lead/tin based solder using a rosin flux.

 

[dprice3844444]

check brownells

 

[Boanerges57]

If you a soldering a part, i assume you will already have to re blue some part of the gun anyway

 

[choppero]

All very interesting replies. My wish is to not have to re-blue a perfectly good barrel, so the graphite or welders chalk to prevent solder flow is a good start. maybe holding the barrel with the sight on the bottom will stop the flux from flowing up.

 

[jimmyraythomason]

Personally I wouldn't use silver solder for a sight anyway. This works great on sights and works at much lower temperatures <http://www.brownells.com/.aspx/pid=645/Product/HOMOGENIZED-SOLDER>

 

[EMC45]

I use 60/40 and 50/50 solder and it works a treat. Lower temp and anchors sight ramps to barrels like a champ.

 

[Jim K]

What kind of job is involved? Many front sights, especially on revolvers, were press fitted, not soldered, and replacements can be installed the same way.

Jim

 

[JimfromTrafalgar]

You can buy "STAYBRITE 8" solder and the appropriate flux at a local A/C supply house. The solder is fairly low temp and has an 1800 psi tensile strength. It's basically a soft solder used as a much better replacement for the old 50/50 stuff. Use the flux that comes in a paste, rather than liquid form, and use it sparingly. Tin the barrel with a little solder and do the same with the bottom of the sight. Then clamp the two snugly and apply a little heat. I've done ribs and forend loops on SxS's using this method and had no problems with losing any of the existing blue. The heat required is low enough that there is no problem with changing metal color either.
Solder prices are through the roof nowdays, so if you know anyone in the A/C business, you might ask them for a little, rather than buy a full roll.
Luck,
Jim
You know what? It just dawned on me. Send me an address, I'll mail you a few inches of solder. You get the flux locally. The stuff you need looks similar to petroleum jelly. Don't use the white paste flux used more for brazing. It won't work well and may very well take off the bluing. I've never tried it on a gun.

 

[choppero]

Jim, thanks for the tip on the flux and solder. I just got stay-brite from midway. And I already have a big jar of the flux. What I haven't done in the past is use the flux sparingly. I'll do just what you suggest next time.

 

[JimfromTrafalgar]

Don't get me wrong when I say use the flux sparingly. I still have not had any problems with that flux taking blue with it. The sparingly part is just that you don't need all that much, and clean up is easier.
Luck,
Jim

 

[Zeke/PA]

It might help while the soldered joint is still WARM, to swab the area with a strong Baking Soda/water solution .
I have a large supply of Eutectic solder that I use and because of the corrosive nature of the flux, the above is necessary.
The particular solder has a flow point of around 450 degrees and a supposed tensile strength of 40,000 psi.
Best part, it was free and I wound up with a 5# spool.