I like stay clean flux-it is diluted so you can use plenty, the BIGGEST secret to soldering is making sure EVERYTHING is grease free.
Clean in acetone and then wash with soap and water and then acetone again....First (using an acid brush) put the flux EVERYWHERE you want the solder to go, especially inside the guard. Put a amall piece of solder (make sure to use low temp silver solder-the highest silver bearing solder you can find) somewhere on the juncture of the blade and guard and SLOWLY heat it-moving the heat so it all comes to the same heat at the same time, keep the heat on the guard, not the blade, and as the solder begins to melt take a POINTED stainless scribe made out of 3/32" pinning stock and direct the solder along the blade/guard junture, continuing to SLOWLY warm the whole thing,
Once I get the solder evenly distributed I wash the whole solder joint off with the acid brush freshly dipped in the flux, flinging the extra solder off the back of the guard, paint the underside of the guard with the flux, and warm it underneath so it flows down there.
Then I let it cool off, shape the whole thing to my liking, dipping in water continuously, and then back to the propane torch to warm it up again and get the solder job perfect.
It may sound complicated, but its not, however, soldering is something that takes a while to master, if you will notice there are a LOT of very good knifemakers who have never learned to do this and only pin their guards on or dont put guards on at all, only glue handles on. It is a challenging process and even if you do it perfectly you have to clean everything up after youre done as solder and flux and the heat make a small mess. If you want to see a proper solder job go to SR Johnson's website and look at his knives!!!!
