cactustrain Posted August 18, 2010 Share Posted August 18, 2010 At some stage I'm hoping to start kitbuilding in brass and have been practicising on some scrap. Having read the article in Hornby magazine Feb 2010, page 35, mention is made of cleaning up joins to prevent them going green and furry. Am I correct in saying that this caused by the acidic nature of the flux used? If you did forget to clean up and had this problem, how would you rectify it? Would you strip the paint and wash the flux off as you should have done in the first place? What is the cheapest and most easily available product that is safe on plastic and metal for washing the flux off with? Just out of interest, why don't electrical joins made with multicore suffer from this problem? Many thanks for any info. on this. Michael Link to comment Share on other sites More sharing options...
cactustrain Posted August 18, 2010 Author Share Posted August 18, 2010 Also, how long does it take for the greening to appear and do atmospheric conditions affect it? Is it necessary to clean all joins, or could you get away with it on small jobs? The reason I ask is that I'm fitting some brake rigging to a RTR engine and it would be easier not to have to wash the metal and plastic assembly as I would need to separate it from the motor. Link to comment Share on other sites More sharing options...
mozzer models Posted August 18, 2010 Share Posted August 18, 2010 washing the solder joints once you have finished stops the green but if you do forget then give it a wash then a rub with a glass fiber brush when i am soldering i wash the item at lunch time then again when i have finished for the day hope this helps Link to comment Share on other sites More sharing options...
mozzer models Posted August 18, 2010 Share Posted August 18, 2010 Also, how long does it take for the greening to appear and do atmospheric conditions affect it? Is it necessary to clean all joins, or could you get away with it on small jobs? The reason I ask is that I'm fitting some brake rigging to a RTR engine and it would be easier not to have to wash the metal and plastic assembly as I would need to separate it from the motor. it all depens on the flux you use i have found with carrs red it 2 to 3 day but with plumers flux the its 3 to 4 hours Link to comment Share on other sites More sharing options...
smokebox Posted August 18, 2010 Share Posted August 18, 2010 Electrical solder uses rosin for the flux. This is inactive, unlike the acidic fluxes used on brass and white metal Link to comment Share on other sites More sharing options...
craigwelsh Posted August 18, 2010 Share Posted August 18, 2010 If you use diluted phosphoric acid as the flux then it'll dilute further with a quick wash in water and I don't have this problem. Cleaning with the brush is normally cosmetic or to remove some solder impurities that have settled on the join. Ultrasound baths are good for cleaning inaccessible areas, I haven't had any issues with wagons around the nooks and crannies since I started washing my work in one; I was the plastic too. If you are fitting brakes is there no way to attach them to the keeper plate or build as a separate unit rather than integrate them into the chassis block? Link to comment Share on other sites More sharing options...
Kenton Posted August 18, 2010 Share Posted August 18, 2010 it all depens on the flux you use i have found with carrs red it 2 to 3 day but with plumers flux the its 3 to 4 hours .. and probably as good a reason as any to leave it for the copper pipes. Washing a brass kit build after every session (I use a mild sodium bicarb solution followed by copious water washes and a fast dry with a blower) is just one of those habits you simply must get into. This is especially true is the build sessions are going to be separated by days. Electrical multicore solder really should be left for electrical work. Yes, the burnt resin is neutral, but it does not was off. It will have to be scratched off and may interfere with painting later. Link to comment Share on other sites More sharing options...
meple Posted August 18, 2010 Share Posted August 18, 2010 [ Yes, the burnt resin is neutral, but it does not was off. It will have to be scratched off and may interfere with painting later. It can be removed with PCB and Flux cleaner available from Maplins, Rapid etc. Link to comment Share on other sites More sharing options...
Kenton Posted August 18, 2010 Share Posted August 18, 2010 It can be removed with PCB and Flux cleaner available from Maplins, Rapid etc. No doubt it can but it is easier not to get it on there in the first place. I'm also not sure how good those spray cleaners are at removal and not just spreading it. Water is cheap and in almost limitless quantities on tap. Link to comment Share on other sites More sharing options...
RMweb Premium Mallard60022 Posted August 18, 2010 RMweb Premium Share Posted August 18, 2010 I often use 'Powerflow Flux' (a cream flux) as it is really good at holding the little bits of solder I drop into awkward places (rather than carry the solder on the iron). It is also good for 'edges' as it does not run away (e.g. brass coach ends to coach sides; brass loco cab etchings). It is also brilliant for white-metal soldering (e.g. loco firebox joining to boiler), as it lets the solder flow well into the join, often acting as a filler if you get it right. HOWEVER 'the job' (as my old craft teacher used to shout above the drone of the Heikel 111s), must be washed and scrubbed thoroughly with the old toothbrush and 'Sif' (other products available) and even then it must be checked again as there is often a residue of white left behind and that goes green over a week as it is still 'active' on the metal. Many moons ago I picked up (from "Building Coaches the Comet Way" I think?) the tip of 'soaking' soldered parts (say overnight) in vinegar. This sort of neutralises the soldered join and creates quite a good surface on the metal for undercoating/priming (when washed of course). This is OK for 4mm but I wouldn't think 7mm loco's would look very comfortable sitting in a bowl of Sarsons! Having said all this, nothing beats washing, scrubbing & cleaning then washing and drying as Kenton and others have stated. I find that a final spray with oven cooker-hood degreaser then washing with warm tap water followed by the blow dry with SWMBO's dryer (I have one in the spray booth but can't be ar**d mostly to go to the garage and fetch it! I don't need one for my dome as anyone that knows me will confirm:rolleyes:). Before painting, the model should really only be handled when you are wearing cotton gloves like a butler would use! Sincerely, J. Eeves. Link to comment Share on other sites More sharing options...
cactustrain Posted August 18, 2010 Author Share Posted August 18, 2010 Thanks for the replies, guys. I'm using Carrs Red Flux and I think the wife has some bicarb somewhere, so I'll try that. If you have got a soldered and painted joint that's gone furry and brought the paint off, is there anything you could do about it? For my Patriot deflectors (here), I just washed them in water and the paint (enamel) seems to still be on after several months, so I presume they are in the clear now, or could this greening/furring problem develop at a later stage? Cheers, Michael Link to comment Share on other sites More sharing options...
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