7mm Finney Battle of Britain

Discussion in 'Area 51' started by mickoo, 10 July 2016.

  1. mickoo

    mickoo Western Thunderer

    A simple out of the box build whilst waiting for etch work for the W1.

    This should help with the 1:32 build in so much as any areas that need tweaking will be found on the 7mm quite quickly and save time and photo tools for the larger version.

    Prototype engine is a late BR wide cab with 4500 gallon narrow tender.

    Everything just fits where it should so far, it takes longer to clean all the cusps off and photograph than it does to actually build it.

    The one thing that is beginning to tick me off, and is not a reflection on this or any other kit, is what I call flux mold.

    No matter how little I put on, scrub and wash afterward, this mold starts to grow, it starts off as small orange spots just hours after washing and if left just green and begins to fur up in a few days. I use the safety flux from Building O Gauge Online, mind it's decanted into a jar and it's pretty low now and been in use for a couple of years I'd guess. I suppose I should decant some more and see if the problem persists.

    It's clearly flux spatter when it's getting hot and spitting and is usually no where near where your working, and usually inside the frames where it's a witch to clean anyway.

    I usually wash in warm water and fairy liquid after each major soldering session, on average every couple of hours, and occasionally a quick squirt with Cillit Bang but only for 10-15 seconds or so as it leaches the 'zinc'? and even nickle silver turns orange.


    You can just see the orange spots here on the inside of the frame near the wheel arch etch fixings, it's been a couple of hours since it's last wash.

    Having said all this, when I did the W1 cab roof last week none of this ever appeared, same flux and 145°C solder but iron at 300°C, mind that was easy to burnish with a soft fibre brush.

    The frame stays were done at 400°C with 188°C solder but I think this spatter has come from the small brass part under the cylinders which is soldered at 300°C with 145°C solder.

    What I'd like is something that'll neutralise this issue and I'm wondering if a sonic bath will help, I'm at the stage now where my work is just not clean enough any more.

    Anyway, more photos as work progresses.

    Mick D
  2. Mr Grumpy

    Mr Grumpy Western Thunderer

    I keep harping on about it, but please try LaCo flux (from Wicks etc) I think you may have said you had been a plumber, so may have used it in that field.
    It's not as aggressive as Powerflux, I have used it for donkeys years in the gas industry. It's passed as safe for potable water, and washes away with warm/hot water.
    Take a look at my 1400, DJH 47 and MMP dogfish. All were built using it. My iron tips last for ever.
    It's not for everyone, and as with any flux, sloppy cleaning will leave green patches. I have had two or three tiny patches over a few years, but cleaned straight off with toothbrush and CHEAP washing up liquid.
    It's great for brass, nickel silver and pewter.
  3. Yorkshire Dave

    Yorkshire Dave Western Thunderer

    I wash any item I've soldered in a bicarbonate of soda (not baking powder) solution which is mildly alkaline and neutralises any remaining solder flux. I suspect Cillit Bang is acidic as it's used to dissolve limescale.
  4. mickoo

    mickoo Western Thunderer


    Yes in a previous employment I was gas, water, refrigeration, plumbing soldering, brazing LOL I've used Poweflux and Bakers and both are very aggressive.

    The Safety flux I use is supposed to be one of the least aggressive fluxes around but I'll get some of this and try it on a few test samples, mind it is a paste and I really do prefer a liquid applied with a very small paint brush.


    Cheers I'll get hold of some of that and give that a go, I wonder if the acid in Cillit Bang is reacting with the flux, I've tried Viakal as well and that's even more aggressive.

    None of it matters so long as the material is chemically clean for painting, but I just like nice clean metal. visually as well as chemically.

    Mick D
  5. Scale7JB

    Scale7JB Western Thunderer

    Oooh, not a southern man at all, but if like one of these one day..

    Didn't they get to the GE during the engine swaps for a short time?

  6. JimG

    JimG Western Thunderer


    I use Templers Mild Telux paste flux because I found there was no oxidisation after use.

    Templers Telux Soldering Flux: Telux is UK WRAS listed for use with both hot & cold water including potable water

    I actually built a brass underframe for a coach as a test piece and didn't do any cleaning off at all and no oxidisation appeared. I've still got that underframe - built in the 1990s - and there's still no oxidisation. The only problem there might be is with painters who reckon that poorly cleaned metalwork using paste fluxes can cause problems with paint finishes.

  7. SimonT

    SimonT Western Thunderer

    I am trying
    Rosin Flux Dispensing Pen | Maplin.
    It is very easy to use and only a small amount dispensed. The 'Safety Flux' spatters and I have a few shirts that have burn holes from this flux.....
    As I'm going to Wickes this morning I might give the LaCo flux a try.
  8. mickoo

    mickoo Western Thunderer


    That's my concern as well, I've used paste fluxes before and they tend to leave a film which is hard to remove chemically and it's always in places where mechanical cleaning can't get to easily.


    I use a small paint brush but must admit the end is a bit frayed now, so perhaps a new one might work better, it does seem to come from areas where I've flooded the joint with solder and hit it hard with a high temp iron.

    Safety flux must change chemically once heated or excessively heated lets say.

    I tried one of those refill pens but didnt really get on with it, think I'll try again and might pick one of those you note up as a trial.


    Yes several ran on the GE for a while, there was a trial first but they got shipped back quite quickly but then a year or two later some were drafted in when the Britannias had to go away for emergency repairs to cracked axles or tender draw bar repairs, can't recall exactly what now, I've a list at home of the engines that ran on the GE, I'll post up this evening.

    Mick D
  9. SimonT

    SimonT Western Thunderer

    it's not one of the refill pens as I never got on with mine either! This looks like a thin marker board pen with a chisel nib. The metal does need to be clean but that is no bad discipline.
  10. JimG

    JimG Western Thunderer


    Another thing I have been doing over the past few months is to use the inexpensive No-Clean solder paste from China in preference to normal solder and flux. This has been partly down to my Scottish tendencies - i.e. to use up as much of the paste before it goes off. :) But I have to confess that I have started reaching for the paste in preference to solder and flux since it does work so well and does have no post-soldering oxidisation. And noting your current comment in the W1 thread, it is easy to got the minimum amount of solder in a joint.

  11. warren haywood

    warren haywood Western Thunderer

    I've painted a few trains in my time:rolleyes:
    Those built with any paste flux are problematic to say the least, you think it's clean but it's not!
    Never had any issues with liquid flux,
  12. mickoo

    mickoo Western Thunderer


    I have some paste solder, I think it's C&L or Carrs, it's certainly handy but I've found a couple of issues with it.

    One, you need a lot of heat real quick and because the iron tip is 'dry' there isn't as much heat flow, it seems better suited to RSU use. Wet the tip with the smallest amount of paste and it solders really well, but then you still end up cleaning off that small sheen of solder left over on the surface.

    Two, any paste outside of the joint flashes over and the flux leaves a dark treacle like residue, much like I've had before on paste flux. It is certainly very good for soldering thin laminated parts onto larger areas or detail parts. But I've not had much luck with larger joints, say slot and tab or butt joints in a half etched slot.

    Mick D
  13. Scale7JB

    Scale7JB Western Thunderer

    Same here Mick, doesn't seem to work for me for joints, but I'd be glad to hear how it's done so that I could try and do as much as possible with the RSU.

    With the little amount of time that I get to do any building at the moment, waiting for an iron to heat up seems like a lifetime..

  14. Ian@StEnochs

    Ian@StEnochs Western Thunderer

    Get an Ersa I-con 1. Mine heats up to working temperature in less time than it takes to apply flux to the joint!

  15. JimG

    JimG Western Thunderer


    Have you any idea what the problem might be - either not enough cleaning, or a deposit left on the metal which is impervious to normal methods of cleaning?

  16. warren haywood

    warren haywood Western Thunderer


    It's residue in certain places where cleaning doesn't shift it. Around the chasis, along footplate edges, front frames, cab corners ect....
    I've tried all sorts of cleaning including just about every cleaning chemical, celly thinners and boiling water without success.
    I've had correspondance with Bracks and he has come to the same conclusion as me, it seems the fatty component of the flux won't desolve and the active ingredient is still held in it.
    Regarding painting issues, firstly the paint won't stick to it so any masking up fetches flakes of paint off leaving bare brass.
    The second problem general shows up a week or two after the paint has been on. Blistering of the paint along joins and I've even seen the green/whiteish residue coming through the paint..
    I'm no expert on fluxes but all the liquid fluxes just rinse away and I've never had any paint adhesion issues with them, in fact I feel they aid adhesion by very lightly etching into the brass but would still advise washing after each build session

  17. Genghis

    Genghis Western Thunderer

    For the avoidance of doubt: I pressed the like button not because of the spotty flux but despite of it! I have one of these to do later in the year. Which year is open to question.:)
  18. JimG

    JimG Western Thunderer


    Thanks for that. I'll maybe do some tests and see what happens with the Templers Telux flux I've been using for some years now. I did tests of several paste fluxes some years ago after I bought some Laco flux and found that it oxidised to bright green deposits after a few days. I then tried Powerflo and got similar results. One other product on the B&Q shelf at the time was the Telux paste and that gave excellent results as far as oxidisation was concerned. However, I've only really used Telux for general purpose soldering and not on metal bodies which are going to be painted. So I might try soldering up some sample pieces and cleaning them then painting them and leaving them for a while to see if I get any adverse results.

    As a matter of interest, does the flux in resin cored solder give the same bad effects?

    It's a pity my brother has retired, He was an industrial chemist and he might have been able to have a look at what might have been going on with paste flux residues. He's nowhere near a lab these days and I know that my sister-in-law wouldn't let him do anything in the house. :)

  19. eastsidepilot

    eastsidepilot Western Thunderer

    I've only ever used liquid flux with an iron and solder paste with the RSU, never really had any problems, a good wash before paint.

  20. mickoo

    mickoo Western Thunderer

    Well that's better.

    New brush, fresh flux, less flux and very little spatter.

    Afterward a clean in hot water with Bicarbonate Soda, no idea of mixture, probably too much, but it seems to come up nice and spangly, making photography a tad tricky :rolleyes:

    Tried several techniques to fix the brackets, traditional solder to the seam and let it wick in, tin the rear surface and hit it with a micro torch and finally solder paste and a micro torch. I'm still more comfortable with an iron truth be told, when your finger gets hot you know it's secure ;) I opted in the end for tinning the rear and heating with an iron and cleaning the residue off.


    We'll see if the flux mold returns over night.