Fine solder crystals - is this normal?

Discussion in 'Plumbers' Talk' started by mbrijun, Jul 4, 2020.

  1. mbrijun

    mbrijun Member


    With a bag of end-feed elbows, a propane blowtorch, Bernzomatic water soluble flux and lead-free solder I set out to learn how to solder. It sort of works, but one thing is not clear. Once the solder cools, it forms fine crystals. I was expecting it to be smother. Is this normal? Was the pipe not hot enough and it cooled down too quickly (I did not touch it with a wet cloth until it cooled down on its own). Overheating the pipe burns my flux and turns the whole thing into a blackened mess.

    The solder is Bernzomatic silver bearing solid wire solder.

    I cut one of the joints with a hacksaw along the pipe, and the coverage of flux is good. But I am able to pull the 2 layers of copper appart with a pair of pliers.

    I think I am close to being reasonably good at this task, but any advice would be very welcome.

    Attached Files:


    METRO MARK Active Member

    Soldering will take some practice to get it right, depending on pipe size heat required, duration of heat blah blah.....

    Best have a look on youtube for some practical examples, plenty out there....A Lot American so ignore them find a British Plumber like this guy

  3. cleggie

    cleggie Member

    make sure everything is perfectly clean.wirewool the copper where the fitting goes on and also on the inside of the fitting.
    masterdiy and METRO MARK like this.

    METRO MARK Active Member

    Yes spend plenty time ensure the joints are clean, and free of grease..Use a good quality flux & Solder
    I can see first picture a gap at the top of the joint.... Indicates the solder has not flowed all the way round
    Lack of flux, or flux burnt off before solder could adhere
    Practice makes perfect
    Before you do your first joint under the floor nail it down and hope it don't leak Ever :confused:
  5. Mr John Melvin

    Mr John Melvin Active Member

    Its lots of years since I left plumbing
    proper flux lead solder blowlamp it all just ran it was bright.
    For the last 40 years or so my life has been electronics YEA.
    I design printed circuit boards and solder in all the component
    Over last years I have noticed the same as mentioned here.
    I do not like Lead free solder and prefer 60/40 mix solder.
    I did find out some of the flux and solders for my electronics work are
    from China and not to usual standard. As in forgery's.
    I just wonder if maybe that is part of his problem.
    Just a feeling maybe thats part of his problem.
    Yorkshire fitting would help.
    I did always like to see a clean ring of solder at the joint.

    Take care

    Johnny M
  6. Timbo66

    Timbo66 Active Member

    I always use LaCo flux. Good quality solder.
    And heat the pipe, not the fitting. This draws the solder into the joint.
  7. mbrijun

    mbrijun Member

    @METRO MARK, @cleggie, @Mr John Melvin, @Timbo66 - thank you for your comments and kind advice. I will keep on practicing. I have gone through a bag of 25 elbows today, but the result is still a bit of a hit and miss. I use a wire brush on the pipe and the inside of the elbow, and I apply flux by brush to both surfaces. I am planning to use soldered pipes in my kitchen for potable water, so I suspect that leaded solder is not really an option. One good tip I received today from a boiler engineer is to dip the solder into flux before applying. I was soldering outside, and it was fairly windy - perhaps that had a negative influence on the outcome as it was interfering with the flame and cooling the pipes too quickly. In your experience, does it matter if propane or butane gas is used? I use propane as it was a cheaper option for my DIY needs.

    METRO MARK Active Member

    All a matter of preferences I prefer to use
    Fernox PowerFlow Flux & Solders Lead & Unleaded. Lead on Central Heating, and obviously NON Lead for potable pipe work...All available form our Host SF
    Map gas in the torch as it burns hotter, gets joints done quicker, More expensive but you get what you pay for....Especially working outside in the cold. Where connecting to existing pipe will suck the heat away from the joint your trying to make.
    For cleaning Fine wire wool, and 3m Scotch pads for cleaning pipe, sometimes a wipe with Mentholated spirits just to make sure all the chicken crisp grease on my hands has not transferred to the clean pipe & fittings :)

    Nothing TOO abrasive that could leave deep scratches in the copper.

    Once soldered leave joint to cool down on its own, don't throw wet rag on it Instantly...The solder crystals need to cool and form without being shocked.
    Once solder lustre has gone greyish you can wipe excess flux off with a damp rag...

    It's easy I taught all my kids at early age (12) to be able to use a soldering iron for PCB work, and how to solder copper pipes etc...
  9. Heat

    Heat Screwfix Select

    I would always add flux as the fitting gets heated, perhaps once or twice as doing so.
    Just use the solder wire dipped in the flux.
    Otherwise the flux will melt away.
    I would recommend old fashioned ‘grease’ based fluxes as they are gentle on copper and allow the solder to flow well.
    Yorkshire traditional flux, or Fluxite grease based or perhaps Fernox grease based are options. But Laco flux gets a good name also.
    Only heat the fitting enough to allow solder to flow around the joint and very little more heat. Too much heat is common mistake made by most diy folk and many plumbers and so called ‘experts’ on instruction videos.
    We don’t grill food at full heat constantly as it cooks, so why should we blast heat at a fitting until it reaches correct heat and then continue using the torch at full power to double the heat of the fitting, resulting in tarnished copper, burnt or vaporised flux and solder running out of inside of fitting? o_O
    You should back the flame away from the joint once it reaches internal melting solder point and just top up the heat as you apply the wire solder, or if wiping.
    Soldering using lead or unleaded solder is not welding and just requires a low temperature.
    Actually worth trying to solder a joint using bare minimum heat to see how well it solders and how little heat needs applied to keep the solder melted in the joint.

    Lead solder (only can be used on heating system pipes now) is much easier to use.
    If you use Yorkshire fittings they only have unleaded solder inside them (as obviously they can be used on potable work as well as heating).
    I would personally only use propane as it frankly is more than hot enough to solder rapidly and is capable of overheating pipes using a Rothenberger Superfire 2 torch or similar.
    I actually used only butane for many years.
    Last edited: Jul 4, 2020
  10. mbrijun

    mbrijun Member

    It turns out the mix is 70% butane and 30% propane. It is a Campingaz torch.
  11. mbrijun

    mbrijun Member

    Moved away from the wind, low flame - better results

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