Mike Hull Wipe down with acetone(lacquer thinner is much better, less oily), then go into the kitchen and scrub with hot water and dish soap, followed by a heavy duty cleaner like TSP, or 409 etc. You will know when it's clean enough as the rinse water(hot) will sheet across the metal, not run in rivulets. At that point, dry with a clean cotton towel, or good paper towels, being careful not to touch any areas to be soldered with your bare hands. Back at the bench, wet a q-tip in flux, and wipe it around the blade where the guard will go, do the same with the inside of the guard, fit them together and heat from the bottom of the tang, and up to the sides of the guard. You can place little bits of solder on the joint beforehand if you wish, but I just touch the solder to the top of the joint (the front of the guard. If the solder on the blade/guard turns black, you've overheated it, and must clean it up and start over, as you will never get a good solder joint if you don't. I wrap a damp, but not dripping washcloth around the blade before applying heat. I hold it on with mechanics wire. It will keep the heat from creeping up the blade and possibly ruining the temper. When your solder flows(and we know it will ) get a small metal pick, I use an old needle file that has been tinned, and has been heated quickly, and has flux on it, and draw it along the solder joint if is not complete. You can flick excess solder off with a solder brush while it is still hot enough to melt solder. You can also just not take any chances of screwing it up, and just leave it alone, and remove excess solder after it's cooled. All this takes place in a relatively short period of time, BTW. Most soldering problems result from improper preparation, and cleaning. As long as you have the proper solder, and the flux that matches it, you should have no problem. Well, less problems anyway
I have old stuff , 'Force 44' silver bearing solder. This is about 95 Sn and 5 Ag and melts about 400F.BTW it's approved for use around food. The flux also by Force is 'Blitz Flux for all metals '. Yes I've used it on stainless. The "silver solder" is of course advertizing hype since it is really tin solder with a little bit of silver. I think they're all the same composition. The flux does make a big difference , if you don't have one that is designed for stainless steel it just won't work
Don't give up, I solder all my joints and its not hard to clean up once you get it down. If you follow Mike's instruction your problems should be over. One thing I did do though was go to a paste flux, it stays in the joint a little longer then liquid and helps me, also I use radio shack silver/solder in the.022 size, this way you don't over apply to much solder. Thats where the clean up problems are, to much extra solder.
Stay with it
Acxetone works for me. I wash guard and blade with a brush and let dry. Stay brite works the best for me. I put the guard on and hold it with a jig. I then put the flux on with the blade pointing up I use a very small pointed brush to paint flux in the joint area. This puts it where you want the solder to flow.I usually cut several small pieces 1/8 inch and lay them on the joint. Start by heating the guard when the flux stops bubbling you are almost there. When the solder melts have a pointed piece of coat hanger ready to run along the joint. Take the heat to the bottom of the guard . That will cause some of the solder to flow through and give you a good solder joint. Sorry this took so long. Go to www.engnath.com
and check out the tutorials they are a lot of help.
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