What silver solder to use?

Hey guys,
I just finished reading the other thread on silver soldering and what torch to use.
I personally like using Oxy/Acetelene. But then again I am old school.
As for Silver Solder, what do you like using on what materials?
What are you using for flux?
I use borax for flux, and silvaloy 355 for solder. Most of the silver solder work I do is on steel to steel parts. Shotgun sights, gas blocks, ribs, etc.

I have been using some stuff that I bought at a yard sale about 25 years ago. It is a slightly yellow colored stuff and is also has slightly lower melting temperature than some of the commercially available stuff. At least that is what I think - I have not bought or used anything other than this stuff in so long I really don't know. It is in about 4" long strips of flat wire perhaps .1" wide and was used in oven brazing of a bezel to a flat surface so it also bent round like a wheel. I'll never have to buy any again at the rate I am using it at.

I use the commercial white paste flux. It has a borax base but some other halide salts are added to help scavenge the oxides. ULTRA FLUX® - Brownells

There is also a black paste flux that is reported to tolerate higher temps, but I have no experience with it.

RWO

I have been using the Silver Brazing paste that Brownells sells. They have 2 types, 1 low fill for tight joints STL 1205 , and a high fill for loose ones STL 1260 ..

The paste has the silver solder ground up and mixed with the flux.

Easy to get exactly where you want, hardly any clean up...

Not cheap, but a little goes a long way...

I personally like the Harris brand safety-silv product line (braze wire in a coil and a separate paste flux)

The flux is in a water base. I have a separate container that I have greatly diluted some of the flux with distilled water and apply it like a wash. This will protect the surrounding surfaces of your work from getting bad oxides when you make the braze joint. But this can cause a problem because it will encourage the braze filler to possibly run to areas that you don't want it to. You will need to decide what the particular job needs.

You should be able to find this product line in stock at most welding/gas supply shops.

I can't remember the numbers but Eutectic did have a very low melting point silver solder that had great strength. I too like the flux made with ground up silver in it, a tinning compound for silver solder! To stop the silver from going where I don't want it I use a #2 pencil and cover the area, it will stop the SS from running where I don't want it.

I am not trying to steer you from trying the braze with the filler metal mixed into the flux, but I would also get one that is a separate braze filler and flux. Sometimes you have a very tight or very loose joint and you really need to be able to control the amount of filler material.

You can always cut off small bits of braze and make preforms that you lay on the joint before you start to heat the joint. I prefer this method compared to trying to dab on the braze material as you do the joint. Much easier to avoid overheating things.

Harris use to sell a small "kit" that had a small container of flux and filler metal. I think the market was as a sample to get you try their product before making a big purchase. With the price of Silver these days a decent size spool of high silver braze is getting expensive.

Using a pencil is a good way to keep the braze from "sticking" where you don't want it. I also like Dry Graphite Film aerosol cans, you can get from NAPA sold as DGF. Easy to spray over a large surface for a protective film.

Welders soapstone marking sticks will also keep solder from running.

MilGunsmith said:

Welders soapstone marking sticks will also keep solder from running.

Click to expand...

That is exactly the info I have been searching for over the last couple of hours. Thank you.

Pops