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Flux Question

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  • Flux Question

    The little hockey pucks of Flux you find at home centers come in two types...There's a red and white can labled, No. 5, and there's a green and white can labled No. 95. Are they interchangeable (I've seen this done, but is it correct to do so)? Is one better with Stabrite, the other more 50-50 or 95-5? Propane or MAPP torch??!! This questions can go on and on...

  • #2
    Be more specific. What sort of material are you intending to join? Copper? If copper, I've always just used No-Korrode, though in certain municipalities the use of any acid based or non-water based flux is now, unfortunately, prohibited, but I digress.
    Use MAPP gas if you want to get the job done faster. It burns hotter than plain propane.


    • #3
      Thanks--Yes for joining copper refrigerant lines...It's one of those minor issues that gnaw at you until you can explain it. I like MAPP gas with silver's just that I notice the solder runs differently sometimes, all other things being similer--except for the flux I use. Wondering if one was better that the other...Stupid, terribly minor I know...thanks again...


      • #4
        Not stupid or terribly minor.....valid questions in fact.
        Sorry I can't be of much further help. In plumbing I have never really bothered to worry about the flux I use very I stated before, I have always just used the No-Korrode brand of flux (the cold weather variety in winter) since I started plumbing and it's never let me down. As far as it's chemical make-up goes I have not a clue.....only that it's an acid based flux. If you can avoid it, stay away from the water based fluxes.....all I can say is that they suck. Doing rough-in's with a contractor recently, we used the water based stuff due to new local codes calling for it and at the insistence of the inspector, and I noticed we had alot more bad joints to re-sweat than I ever seen using regular flux. The stuff is great for washing off your hands, but awful for it's intended purpose. Alot of guys have been buying the stuff, dumping out the contents, and filling the jars back up with No-Korrode to fool the inspector hopefully you don't have such anal codes in your area. The silver solder is very good, and preferred for sweating larger lines such as boiler manifolds and the like because it tends to be stronger. 95-5 is usually always what I use for every sweat job. As far as the solder running differently, this could have more to do with your sweating technique....or amount of flux used.....than anything else. I have not seen much differnce between using tinning flux and No-Korrode as far as this goes before. Anyways, good luck.


        • #5
          i used to use the red and white can...until

          i accidently picked up a green and white can which turned out to be oatey #95 lead free tinning flux in a green aand white can. this is a grey flux and is a little thicker than the standard. i did not feel like going back to the hardware store so i tried it. it is awesome. seems to clean the joints better and the solder seems to stick so much easier.

          this is all i use these days

          by the way, i mainly end up dealing with copper


          • #6
            I don't know if I would call the code requirements 'anal', which would seem to imply they are excessive. The reason for not using acid-based fluxes I believe is because of the problem that the flux which remains in the lines after soldering can increase copper levels in the water. The system should be drained and throughly flushed after testing and for the first few months (in a new system) flushed occasionally to remove flux residue and any small metal particals that may be still in the lines. I know of one family who had a new house built and the plumber did not flush the water lines at all. No water test was made as it was city water. The family had problems with their dental work for the next year. Fillings were coming loose and the water attacked other dental work too. Don't know if the plumber was ever found at fault or not or any settlement made.

            I agree that No-Korrode is the best for most copper work, and have used it for 99% of my soldering work over the past 27 years. However, I am careful not to use too much (especially on the sockets of fittings) or to get any on the inside fittings which do not form part of the joint. Puting too much flux in the socket just gets pushed into the fitting when the pipe is inserted, kinda like putting pipe dope on the FM threads of a fitting, doesn't so any good.

            When finishing (capping) a joint if necessary I like to dip the end of the solder into the flux can to coat an inch or two or solder with flux, this way I do not have to apply any more flux to the outside of the joint. The last couple inches of the solder will be warm from the heat of the joint just soldered and when stabbed into the flux can only a small amount will adhere to the solder, just a thin coating but it is enough to make your solder flow nicely around the joint. I have used this trick when finishing large joints (2" to 6" copper) with 50/50 back when it was allowed for domestic water service with great success, but it works with 95/5 too.


            • #7
              Good points Bob. But I must say, after years of using acid based flux, I have never heard of the dental problems you say happened in that instance, though being as I don't have alot of knowledge concerning this issue I'm not going to deny it could happen either. But all I can say is if that did indeed happen, the plumber in question must have literally used a putty kinife to apply his flux to the fittings with!!
              Ever try the water based fluxes? They're terrible. Great for washing off your hands, horrid for performance. I refuse to use it, and I know lots of plumbers who absolutely ignore the codes calling for it. There are *always* leakers after using the junk after any new construction, whereas it is common for not a single one using the acid based. Go figure.
              Your point about flushing the system after installing/testing is a great one, though I must admit not a common practise among most plumbing contractors....matter of fact, in my experience working with over half a dozen licensed contractors in my state over the last 5 years, I have hardly ever seen them do this.....they merely hook up a pump to a washing machine valve, test the system for leakers, and drive away. It would be wise for any new home owner to do this themselves (or request the contractor to do so) before moving in to assure this is done properly.

              [ 05-22-2004, 01:59 PM: Message edited by: David M. ]


              • #8

                You're right, the plumber must have been careless and sloppy on aplying flux and assembly.

                I did a little searching on the 'net after making my previous post to see what I could find out about the subject of dental-related problems and water quality, didn't turn up anything concerning the problem I mentioned but there was a link to a UK plumbing code site that required domestic water systems to be flushed prior to being turned over as complete.


                • #9
                  I use Silerbrite brand solder for everything Its water safe and melts and holds great. I never heard of water based flux and I dont think I want to. If peoples fillings are falling out I think they should look at their dentist a little closer and less at their plumber