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  • A question about "Sweating"

    I was reading a short book detailing events at the Alamo during Texas' early actions to beak away from Mexico. One section had a brief overview of Jim Bowies knife, which has become legendary.

    According to historical sources Bowie's knife had a channel shaped piece of brass on the spine, the purpose of which was to trap and opponent knife. That piece of brass was stated to have been "sweated" on. I'm familiar with the useage of sweating as applied to copper piping. What has me confused is how, in a day where the forge and anvil were the predominant tools for knife making is how they might have went about "sweating" the brass to the spine?

    Any and all thoughts are appreciated.

    BTW, to each and everyone of you I wish you a Merry Christmas, and a Happy, Prosperous New Year.
    John B

  • #2
    Merry Christmas & Happy New Year to you & yours also!

    Comment


    • #3
      Metal joining processes, via melting a softer metal with a lower melting point, had been around a long time when Jim Bowie's knife was made.

      http://www.ersa.com/soldering-history-en.html

      Today's use of the term "sweating," has never made much sense to me as a descriptive term. But I imagine at some point in soldering's evolutionary past it made more sense.
      Lynn (Huntsville, AL)

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      • #4
        What a crock of BS. Jim Bowie's knife didn't have the addition of the brass. Perhaps on copies but not the original that came to be known as a "Bowie Knife". There are hundreds of variations to the design both pre-Alamo and post-Alamo but only one "Bowie Knife".

        Comment


        • #5
          I have no idea wether or not Bowies knife had an added brass spine but ----
          Way back in the 40s when I took plumbing shop in high school the teacher told us that it was called "sweating" because the little beads of solder that oozed out of the pipe junction looked like sweat.
          But then I am not a plumber and don't play one on TV.
          Bill
          I cut it off twice and it's still too short!

          Comment


          • #6
            I thought it was "sweating" because that was when the flux went clear, dripped off like sweat it was the correct temperature...when thinking about it though, while that might make sense, it means that nearly every thing can be "sweated" since flux varies etc. etc.

            Comment


            • #7
              My understanding:

              Soldering as I do it involves heating and adding solder, which is drawn into the joint.

              "Sweating" as I know it involves "tinning" both sides of the joint, applying solder to them, then putting them together with flux and heating, using the solder already present from tinning to complete the joint. Can make a thinner joint with little external marking by the solder.

              Others use the term almost generically for soldering.
              1601

              Keep eye on ball.
              Hashim Khan

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              • #8
                As I have always understood it, J Teirs has it right. Maybe it's a Midwest thing.

                Sarge

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                • #9
                  It's a common term for soldering either hard or soft over here, I still refer to it as that
                  Mark

                  Comment


                  • #10
                    In the old days plumbers wiped a lead (Fr: Plomb) joint a skill pretty much lost.

                    from the old manual:
                    .... The strength of a wiped joint depends not only upon the amount of solder used, but upon the quality of the solder. A joint may be well wiped and of symmetrical shape, and still be a poor joint, owing to its being porous. When porous, the joint will "sweat" as it is termed, that is, drops of water will ooze through the solder. This is caused by the poor condition of the solder, due usually to a lack of the proper amount of tin. Solder when made of the proper proportions of lead and tin is much stronger than the lead, and it is the tin that gives the solder its strength by cementing the mass of metal together.

                    Max.

                    Comment


                    • #11
                      The OP is describing the common "Spanish notch" which was a feature on knives used for fighting. Not likely used on every blade made, of course, but definitely used on some. Making it of brass also allows it to be serviceable.

                      Comment


                      • #12
                        Drops of water would ooze through the solder? I don't care what alloy of solder you use, if it is solid it will not allow any water to pass through it. Only if there are voids can anything "ooze" through. And voids would usually indicate either too little solder in the joint or areas where it did not wet one or both of the surfaces being joined.

                        I have seen poorly soldered joints in an air system burst apart. They were originally holding with flux only, no solder had penetrated the joint. Fun to watch everybody jump and run when a 150 psi air line lets go.

                        Bad technique, nothing oozing through the solder. Same thing for water lines or almost any other fluid.



                        Originally posted by MaxHeadRoom View Post
                        In the old days plumbers wiped a lead (Fr: Plomb) joint a skill pretty much lost.

                        from the old manual:
                        .... The strength of a wiped joint depends not only upon the amount of solder used, but upon the quality of the solder. A joint may be well wiped and of symmetrical shape, and still be a poor joint, owing to its being porous. When porous, the joint will "sweat" as it is termed, that is, drops of water will ooze through the solder. This is caused by the poor condition of the solder, due usually to a lack of the proper amount of tin. Solder when made of the proper proportions of lead and tin is much stronger than the lead, and it is the tin that gives the solder its strength by cementing the mass of metal together.

                        Max.
                        From J Tiers,
                        "Sweating" as I know it involves "tinning" both sides of the joint, applying solder to them, then putting them together with flux and heating, using the solder already present from tinning to complete the joint. Can make a thinner joint with little external marking by the solder.
                        If a pipe joint were made in this way I would say it would be a recipe for a leak. If the two sides of the joint have so little solder that they can be assembled, then they do not have enough to fill the space between them and voids are almost certain. Only by luck would a good, 360 degree seal be accomplished. If you are sweating pipe, adding more solder is a must.

                        I would think that adding a brass strip to a knife would be somewhat simpler and the pre-tinned technique may work there. But even here, adding more solder after heating would probably be beneficial to prevent voids. You wouldn't want your knife to fall apart in the middle of a knife fight.

                        Surface mount devices can be reliably soldered to PCBs with a similar technique, but this is not the common technique (solder paste and heat) used for them.
                        Last edited by Paul Alciatore; 12-13-2014, 02:41 PM.
                        Paul A.
                        SE Texas

                        Make it fit.
                        You can't win and there IS a penalty for trying!

                        Comment


                        • #13
                          Originally posted by Paul Alciatore View Post
                          Drops of water would ooze through the solder? I don't care what alloy of solder you use, if it is solid it will not allow any water to pass through it. Only if there are voids can anything "ooze" through. And voids would usually indicate either too little solder in the joint or areas where it did not wet one or both of the surfaces being joined.
                          This was a quote from a treatise on plumbing published in 1910.

                          What did they know!
                          Max.

                          Comment


                          • #14
                            Originally posted by Paul Alciatore View Post
                            Drops of water would ooze through the solder?
                            Read carefully - the solder joint described is porous, so yes, water could weep through porous solder.

                            Comment


                            • #15
                              Originally posted by Paul Alciatore View Post
                              Drops of water would ooze through the solder? I don't care what alloy of solder you use, if it is solid it will not allow any water to pass through it. Only if there are voids can anything "ooze" through. And voids would usually indicate either too little solder in the joint or areas where it did not wet one or both of the surfaces being joined.

                              I have seen poorly soldered joints in an air system burst apart. They were originally holding with flux only, no solder had penetrated the joint. Fun to watch everybody jump and run when a 150 psi air line lets go.

                              Bad technique, nothing oozing through the solder. Same thing for water lines or almost any other fluid.
                              Lets not mix processes.
                              The 'wiped joints' that were used on lead pipe were closer to body solder in alloy, 70/30 if I recall, and were a mechanically built up ball of solder that would indeed leak if not properly executed. The solder was applied at a temperature just above the melting point, and when it reached the plastic stage it was formed y hand into a ball around the ends of the pipe. I was in the last plumbing class in 1968 that was taught this process. It is thankfully no longer in use. The only others that I was aware of that practice this method were telephone linemen that maintained the underground lead sheathed cables. Bet they don’t miss it either...

                              see:
                              http://www.plumbing-geek.com/lead-pipe.html




                              From J Tiers,

                              If a pipe joint were made in this way I would say it would be a recipe for a leak. If the two sides of the joint have so little solder that they can be assembled, then they do not have enough to fill the space between them and voids are almost certain. Only by luck would a good, 360 degree seal be accomplished. If you are sweating pipe, adding more solder is a must. <<snip>>
                              As far as pipe is concerned JT, you are spot on. You are correct about PIPE joints requiring the addition of solder, but many joints may be successfully made with only the residual solder if the fit is good before the parts are tinned.

                              Shotgun barrels are assembled by tinning both surfaces and then reheating them with no more solder than the tinning left behind. I have a barrel weight that I fashioned and applied to a High Standard pistol barrel 30 years ago that is still in place.

                              paul
                              paul
                              ARS W9PCS

                              Esto Vigilans

                              Remember, just because you can doesn't mean you should...
                              but you may have to

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