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Discuss Soldered Joints Rough / Grainy Finish at top of Joint (Lead free Solder & Mapp) in the Plumbing Forum area at

  1. Roy_66

    Roy_66 Member

    Some pictures first to illustrate my Question (I understand as new poster I can't yet put them in direct).

    Outside picture:
    Photo by Roy_6666

    And cut open (this is topside):
    Photo by Roy_6666

    Can anyone give me view please on how to get better (smoother) soldered 15mm joints (I'm doing my lead free re-training at the mo) or if from pics above its "good enough".

    I'm using:

    1. Rothenberger Superfire2 (Mapp gas) with the smaller jet and cool swirl tip fitted (Get overheating with the larger turbine tip when gas turned down for 15mm)
    2. Laco flux (tried and rejected oatey 95 self tinning - no benefit)
    3. Lead free solder "Oatey 29024 Safe Flo 0.117-Inch ga." from Amazon:

    My method is:
    • Torch is turned down so just get a bit of bright blue flame and warble (Same result on higher gas)
    • I am soldering with torch on the inside of the elbow (Cos that's what my project requires)
    • Clean and flux pipe and fitting (not too much flux in the fitting)
    • Assemble and wipe off excess flux from the fitting (leave a mil or so on the pipe near the joint - no big blobs tho)
    • Quick waft around with torch (pipe also), then generally heat the middle of the fitting, then move underneath till I get a melt on the top of the joint, then wipe solder on.
    • Reheat as required for the second joint of the fitting (backing off / reheat is the hardest bit i think)
    • Flick off snots (if I remember) - just for practice.
    • Bottom of joint looks ok, but solder at top is rough / grainy (After cooling/setting, joint has been wiped clean of flux and wire wooled before photo)
    • Sawing apart looks good to me and no pool of solder inside (Photo is the top but underside was similar)
    My questions:

    1. Any ideas what to try to get a better finish ? (I've seen better but on bigger fittings). I would be no good at wiping joints (and my project is confined area)

    2. How much of flame should be in the fitting ? (I slowely move in when I think its not melting)

    3. Is the smaller Rothenberger cool tip foolproof against melting, if I go lower on the gas ?

    Watched loads of videos, but perhaps you have a favourite, as a good way to answer.

    I have got a fresh pot of Laco to try now (I did stir the old one . . . )

    Many thanks,


    P.S. I'll post my project separately (New elbow in Dot/Dab wall)
    Last edited: Mar 21, 2019
  2. Harvest Fields

    Harvest Fields S. Mod Trusted Plumber GSR Top Contributor!!

    No pictures mate.
  3. Roy_66

    Roy_66 Member

    Sorry trouble with the pictures . . . please see next reply . . .
    Last edited: Mar 21, 2019
  4. Roy_66

    Roy_66 Member

    Sorry for slowness. Just guessed I can't put in pictures (even if hosted elsewhere) so replaced with links to photobucket.
    Last edited: Mar 21, 2019
  5. gmartine

    gmartine GSR

    At a guess without seeing pics you might not be using enough heat to get decent flow and or you're wiping before the solder has set hence the grainy finish. If you have a great deal of snot you're using too much solder, try to start the solder at the rear of the fitting allowing capillary action to work it around. That way you get the best available finish as well as knowing if the solder has completely taken around the fitting without using too much.
  6. Rob Foster

    Rob Foster Top Contributor!!

    I seem to remember some stuff ..Plumbers Black ? used to stop displayed soldered pipework looking scruffy gents urinals etc. used it but cannot recal the name
    chking....ukpf january 16 2011 ! found it ha ha
    Last edited: Mar 21, 2019
  7. Roy_66

    Roy_66 Member

    Many thanks for the ideas.

    I had the same result with a higher torch level. I do try to apply the solder on the other side from the flame. Think I'll do just half a fitting as an experiment (i.e. only first joint), and only solder with the torch removed once I get a melt just to see how that looks (So the cause won't be the flame accidentally blasting the joint. The one in the picture had very large snots, and was well set before I wiped (I generally exit the garage and open the doors as soon as torch off, then come back and wipe clean etc. later).

    I'll also try a new pot of flux.

    Should there be any bright blue flame on the torch or is that still too big a flame ? (I only had a little bright blue. You have to be careful with Rotherberger not to turn down too low, at least with the larger turbine tip, not sure about the smaller one I've got on now - need to experiment.)

    One thing I don't understand - with a traditional torch the hot bit to use I think is at the end of the inner blue cone (some say use last 30% of total flame). With Rothenberger swirl tips where do you aim for (inner blue multiple cones only a few mm long so well away from the copper)
  8. Roy_66

    Roy_66 Member

    Thanks Rob.

    My stuff will be behind a plastered wall, so I don't need to polish up ( . . . though I will :)).

    I'm just looking at the finish thinking I'm not doing the soldering quite right (when I compare against professional work)
  9. Rob Foster

    Rob Foster Top Contributor!!

    I think you are being a bit too pedantic. get some scrap 15 and 22 pipe stick in a vice and have a play with a few end feed fittings. try it vertical, horizantal etc. and see which suits you. map gas is very hot and might be too hot, i use it , but propane is good, butane is ok in summer but carp in winter in empty buildings , and let us know which is best centralheatking also haveca play with leaded solder
    and unleaded, then which flux ? laco for me, tried them all over the years yellow, bakers blue, liquid ones ...maybe a strawberry flavoured laco would be good, esp when ur covered in it , its on your sandwiches ...and some are wicked if you pick your nose or rub ur eye ..there you go centralheatking
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  10. Roy_66

    Roy_66 Member

    Think you are probably right :)

    I did do a training piece first, using leaded and lots of T-pieces and vertical fittings with sizes 28mm, 22mm.

    Only got into trouble when I got down to 15mm and the Rothenberger torch with standard as supplied large turbine tip overheated red hot cos I turned it down for the 15mm stuff. I guess when turned down the flame front goes into the head with bad results. (Instructions say 1 inch flame min, but everyone seems to thing that is wrong - just look at it for starters). Now got the smaller tip and jet, but perhaps still turned up too much.

    So main thing I think I need to try is cooler, and perhaps I am still accidentally blasting the joint after I've applied the solder when I move in to the second joint. Also by second joint I'm starting to worry I'm trashing the flux. I need to relax a bit more and remember these are just training ones :)

    Will also have a go with Propane - think I've still got some.


    Last edited: Mar 21, 2019
  11. Chuck

    Chuck Well-Known Member

    I agree with Rob Forster, MAPP is an acetylene substitute because it burns with a very hot flame. Try using a propane or butane torch instead.

    Another possibility is your flame is set towards the oxidising end of the spectrum (excess oxygen, blue hissing/roaring) but for soldering you want to be neutral or reducing.
    • Like Like x 1
  12. Rob Foster

    Rob Foster Top Contributor!!

    While your there get some lead and have a play ...We will,tell you what to do ..I know lots
    like lead to copper soldered joints might as well learn if you are intrested this much
  13. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Any pics as your using the same set up as me

    Clean pipe and fittings with steel wool
    Flux pipe
    Insert into fitting
    If vertical joint wipe flux off
    Turn torch on flame about 2” long
    Heat bottom joint first holding flame at just the top of the socket bit
    Wait till joint is ready eg sucks add about 5-6mm of solder (15mm tube)
    Now do the top joint without moving the flame
    Leave to cool for a few minutes
    With a wet towel clean the joint
    Scotch brite pad for buffing


    It’s all down to practice

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  14. Roy_66

    Roy_66 Member

    Thanks Chuck, thats interesting. I'll try turning down until all bright blue bit gone, but check first torch does not overheat before doing any soldering. I'll keep a count on how long until I get a melt and report back.


  15. Roy_66

    Roy_66 Member

    Thanks Shaun. There are now links at the top to the two pictures on photobucket (as I think I'm not alowed to add pics directly yet). Your stuff looks neat. I need to experiment. Could be that I solder ok but then accidentally waft the torch on it while still liquid. So try lower torch / propane / then lead (got a bit left from the good old days :))

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