Which solder/flux combination do you use for etched kit construction?

Discussion in 'Techniques' started by Mike Trice, 23 October 2019.

  1. Mike Trice

    Mike Trice Western Thunderer

    For the first time in years I have attempted to scratchbuild a tender chassis out of 0.4mm n/s strip. Something that is causing me grief is getting a bridge of solder to join two pieces of strip held at right angles to each other. In spite of lots of flux the solder seems to adhere to each side with surface tension stopping the solder bridging the joint.

    I am using Templer's Telux Soldering Flux and use a non-resin solder with a 60/40 Tin/Lead alloy. My soldering iron is an Antex 50W with a straight chisel tip around 5mm across.

    Can anyone recommend a solder/flux/tip shape combination that would allow me to achieve the quality of soldered joint seen on this forum?

  2. Tim Watson

    Tim Watson Western Thunderer

    Phosphoric acid & 145 deg solder.

    neaston and Mike Trice like this.
  3. Scale7JB

    Scale7JB Western Thunderer

    I know some are against it, but I wouldn't be without my powerflow flux, the plumbers stuff in the yellow pot.

    Great for holding parts in place too whilst laminating, as it's very viscous.

  4. Mr Grumpy

    Mr Grumpy Western Thunderer

    I used LaCo flux...also at work as a gas engineer.
    Washes off in HOT water. Not as aggressive as the Poweflux sold in yellow containers.
    Absolutely no problems with cleaning up and painting. Doesn’t stain nickel silver. Some people will say it hinders painting. It is not the flux, just poor preparation of the model, same as with any flux.

    Edit: our posts overlapped JB
    Scale7JB, Ben Alder and mickoo like this.
  5. JohnG

    JohnG Active Member

    Contact 'Solder and Fluxes' on sales@soldersandfluxes.co.uk (usual disclaimer)

    They are specialists in the soldering electronic industry and now sell to modelers and model engineers in small quantities. They sell modern fluxes some of which are 'no clean' and importantly they are 'safe'. They are also owners (I think) of Frys Fluxite and Bakers Fluid. You will find them very helpful, its a family business I think, based in Chepstow, just over the old Severn bridge.

    I can only recommend them as a satisfied customer.

    Good luck, John
    mickoo likes this.
  6. mickoo

    mickoo Western Thunderer

    60/40 typically melts at 188°C, use 145°C and that'll help.

    However, I suspect your biggest problem is simply lack of heat or sustained heat.

    Nickel silver is a very good conductor of heat and will sap the heat away from the iron very quickly, that's why once you have the solder flowing it'll zap down a joint in a flash.

    Lots of folks get by with a 50W iron, I never could and up rated to 80W and solder pretty much everything with it set to 400°C, get in and out fast. Though to be fair, nearly all of my work now, except detail work, is done with a micro flame.

    The only down side is super heated flux which spatters and is a bit of a devil to clean afterward.

    I use safety flux from Building O gauge on line Building O Gauge Online - Soldering and apply with a small pint brush.

    Just about every reply you get will be different here, all good and well and I went through the exact same process a few years back; the trick is to try a few and find one that works best for you, but I do think your iron is going to be your main culprit.

    As a quick test, buy a small cheap micro flame, waft it over a test piece and see if the solder then runs okay, if it does, then it's a lack of heat issue, if not it's your flux or solder.
  7. JimG

    JimG Western Thunderer


    I'm with Mickoo in thinking that there's not enough heat on both pieces of nickel silver. I use the same combination of flux and solder and I don't think I would have a problem soldering such a joint.

    I also wonder if you are getting enough contact area from the tip. I find that the plating on some tips these days is not all that wonderful. The bit for my 100W Weller was pretty well useless for getting heat onto metal because of rough plating. I checked that the underlying metal was c0pper then filed through the plating to the copper to establish a flat contact area, going back to traditional tinned copper soldering. It does need the occasional cleanng up with a file, but I do get a good flat area to transfer the heat.

  8. Mike Trice

    Mike Trice Western Thunderer

    Thank you for all your replies. The tender in question is 4mm so somewhat smaller areas to heat up.

    I managed to find some LRM 145 solder I had bought some time ago and never used. The difference is astounding even with my current Templer's flux and the problem has been resolved with the joint flashing over instantly. Definitely a 145 convert now.

    Should I have a go at 7mm (and it is very tempting seeing some of the work on this forum) then I would probably upgrade to a higher wattage iron.


    P.S. I already have a LiteSold 70 watt iron with large 11mm copper tip and a Nimrod SolderPro 100 gas iron. I guess that should have 7mm sorted.
    Last edited: 24 October 2019
    Peter Cross likes this.
  9. P A D

    P A D Western Thunderer

    Hi Mike,
    I use an Antex TCS 50 watt iron with 145 solder and the flux that Mickoo mentioned. However, it's really a bit low on watts and at times it's found wanting and I then use the micro flame. The right tip helps and I find that round end wedge type works best for me. I use the biggest one shown below most of the time and one of the smaller ones where less contact required and maybe access is tight for the bigger one.

    At some point I really must upgrade to something better, probably an 80 watt Ersa soldering station, as I've read and heard good things about them from people whose work I admire.

    s-l1600 (2).jpg
    Peter Cross and Mike Trice like this.
  10. Scale7JB

    Scale7JB Western Thunderer

    40W with a big chisel bit :eek::))

  11. Ian G

    Ian G Western Thunderer

  12. michl080

    michl080 Western Thunderer


    I noticed that the diameter of the solder wire makes a difference. The effect you describe could be caused by a very thick solder wire. I am using 0.5 mm solder 180deg wire. The liquid solder needs to fill the gap between the parts. If the diameter is very small, the wire fits better into the gap. The cohesion between brass and solder will pull the solder into the gap as soon as the distance between the solder wetted surfaces is small enough. Complicated.

  13. 3 LINK

    3 LINK Western Thunderer

    I get a sore throat that seems to coincides with when I'm soldering, I use ordinary 60/40 solder with safety flux from Building O Gauge online. Has anyone else had the same problem. I always have ventilation to the workshop, but now I'm running a fan and a simple face mask, which seems over the top but solves the problem.

  14. Mudhen

    Mudhen Western Thunderer

    No, I don't think this is unusual, most people just ignore it. I suffer badly if I use cyno.

    3 LINK likes this.
  15. eastsidepilot

    eastsidepilot Western Thunderer

    145 deg solder, phosphoric and a 100w Weller , 50w Antex which can have the temp turned down for white metal and an RSU depending on application.
    For wiring on motors etc. I have found a small Antex 21 watt is ideal.

  16. farnetti

    farnetti Western Thunderer

    I use the Ersa 80 watt at home and the Antex TCS50 at my club. The Ersa works every time, the Antex not always powerful enough for 7mm larger items, even with largest tip. A very quick blast with a torch always works as well.

  17. P A D

    P A D Western Thunderer

    Hi Ken,
    It sounds like your experience with the TCS50 mirrors mine, with you using the same solution when it is found wanting. I must invest in an Ersa!

    Ps. Any progress wit the MOK BR standard 4 tank?
    JohnG likes this.
  18. JohnG

    JohnG Active Member

    Hi Peter,

    The ERSA is well worth it, I have an Analog ERSA 8o and the latter RDS 80 both of which are superb, just picked up another ERSA 80 for work for £60 second hand and a handful of tips. If I see another I'll contact you.

    regards, John.
    Last edited: 27 October 2019
  19. Tim Watson

    Tim Watson Western Thunderer

    The Ersa I Con1 set up I have is excellent for 2mm scale work, as you can crank the temperature up and down very quickly. You can never have too much heat when soldering (at least with brass & N/S) - quick in and out is how I work. However, if it is turned up for a big bit then the soldering iron needs to drop back to 100 deg above the solder temperature otherwise it will ‘go stale’ on the bit, this iron will do that automatically, although I generally change it manually. The iron is normally running at 250 deg for my ‘standard’ 145 deg solder

    I recently made a relatively small brass 009 kit for someone and found it much harder to work with than N/S: it conducts heat away too easily.

  20. John Bradshaw

    John Bradshaw Member

    I tend to minimize use of solder, soldering is about using and controlling heat, if that is right the solder metal will flow naturally. I find some use a lot of flux to compensate for not applying enough heat. Apologies if this is unhelpful.
    adrian and michl080 like this.