Silver Solder and questions about it

J S Machine

J S Machine

Well-Known Member
I'm going to do some slip joints here soon, and I need to be sure I buy the right supplies. I stopped by Lowes on the way home from work tonight to pick up some silver solder and some flux. I have a small propane torch with a very old torch head. I thought I might pick up a new torch because of the fear that the older one may not work properly.

I found that none of the packages of solder had "silver solder" written anywhere on them. The only thing I could find that was solid wire and not rosin or acid core says "lead free solid wire solder".

It says 419* melting temp and 6950psi high tensile strength. I also picked up a new torch unit, and it is labeled for propane. I can't find sufficient information to tell me whether or not I can run a MAPP gas cylinder on this "propane" torch head. I know that MAPP gas burns hotter. Do I really even need MAPP gas for this soldering bolsters to liners, or will propane do the trick?

Also bought to different kinds of flux because I don't know which one to use.
Thanks for the info guys. I have one that says "tinning flux - for dissimilar metals" and one that says paste flux - for general purpose soldering". Which one of these will work for what I'm trying to do?

Thanks guys.
 
I doubt you're going to find the right stuff at a big-box store. I buy Sta-brite solder w/ Sta-clean flux from my local welding supply store (Airgas). Make sure you buy the correct flux for your solder.
 
+1 on these guys comments.

There are different fluxes and different alloys of silver solder. I went Erin's route and went to the local welders supply (Prax-aire) and picked up some silvaloy and flux.

Propane should work fine for silver solder. Silver brazing is high temp silver solder (1400 degree melting point I think) so then the Mapp gas may be a plus.

I've used propane and mapp gas both with my torch head though.

-Josh
 
I think you will find silver braze heats begin around 800° Silvaloy comes in different temp ranges, and most will respond well to most borax based fluxes. The temp range for the Brownells standard Silvaloy is 1175°, or around that temp. Very good stuff. Very strong. There is also a yellow colored Silvaloy that matches brass pretty well.
The torch heads made for Mapp gas are much superior to the standard propane heads, if you're wanting more heat, and do very well with just propane. They are more expensive though. I keep Mapp on hand, but seldom have to use it in the Mapp torch heads. Usually only when I brass braze something.
 
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