The BladeForums.com 2024 Traditional Knife is available! Price is $250 ea (shipped within CONUS).
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Couple of quick answeres, I have not see the brand staybrite sold locally but can be ordered from alot of knife suppliers.
You can try others, this brand does seem to work well. They key is to have a good clean joint and be prepared to deal with a poor joint.
I have not seen silver solder with internal flux but it may exist, I am not sure how well this will flow into the joint but may be worth a try.
Tip up, place small pieces of solder around joint, heat from bottom. when solder starts to bubble remove heat and see if solder melts, if not apply heat and watch. It takes a couple of seconds for the heat to soak through the metal and reach the solder, if you keep the heat applied until the solder melts you will fry your flux and may ruin the joint.
I would suggest you order staybrite and save yourself the trouble of not knowing how well your solder and flux will preform, just on last variable.