Hi folks,
If you're on several modelling fora you will probably see this post several times - apologies!
I'm looking to canvas views (and advice) on soldering flux as there seem to be a lot of conflicting opinions and 'facts' (not sure whether the quotes are justified).
There are several types of soldering that I want to do: electronics, track (on PCB), brass kits, white metal kits and, occasionally, track on plastic sleepers (e.g. turnouts).
So far, it seems that for electronics, simple multi-core solder is fine, but liquid flux won't hurt (so long as it's not acid?).
For all the other jobs I've had advice that I should only use liquid flux, that I can use multi-core, that I can use both, that acid flux will attack a joint unless washed and that rosin flux (as in most multi-core) can leave a film which doesn't take paint very well.
Any advice gratefully received!
Pete
Deja vu! (MERG ;-) )
You seek enlightenment from the master: The Art of Soldering (https://www.amazon.co.uk/Art-Soldering-BP-R-Brewster/dp/0859343243)
Cleanliness is essential. I've gone off using a scratch pencil (though I understand they no longer use nasty glass fibres) and prefer Garryflex blocks (https://www.amazon.co.uk/Proops-Garryflex-Abrasive-Cleaners-Postage/dp/B078Y3ZF1M/ref=sr_1_5?adgrpid=54742478578&hvadid=259068625589&hvdev=c&hvlocphy=1007293&hvnetw=g&hvqmt=e&hvrand=13389441008476149763&hvtargid=kwd-302705836441&hydadcr=29352_1792266&keywords=garryflex+abrasive+blocks&qid=1700582860&sr=8-5)(effectively track rubbers). I find the pink 240 grit most generally useful.
For soldering droppers to track I use ordinary electronics cored solder helped along with my own concoction of rosin (colonophy) dissolved in isopropyl alcohol but meths or bio ethanol should do just as well.
Tinned PCBs should just solder using cored solder. For Veroboard, copper-clad sleepers and so on, clean with a Garryflex block. Ordinary electronics solder can work well, though it is easier not to overdo the solder if using Carr's solder paint.
If you need solder really to flow and form a thin film on brass then Powerflow flux (https://fernox.com/product/powerflow-paste-100g/#:~:text=Powerflow%20Flux%20is%20a%20soft,It%20contains%20no%20zinc%20chloride.) works wonders, but it is an aggressive flux and needs washing off fairly soon (not put back into the box for working on weeks or months later). Hot water and bicarbonate of soda or weak sodium hydroxide solution seems to do the trick as does scrubbing with household cream cleaner.
Whitemetal - I've only ever used the Carr's flux specifically for it.
I had a supply of 1960's flux solder that lasted until very recently.
This was great at all applications, brass kits, track wiring, tin sheets, PCB's etc.
However I am almost out of this now and the modern solders are nowhere near as good!
I guess that this is because they no longer contain materials that are harmful to the environment and/or the health of the user?
But for what ever reason I wish I had more of the old stuff!!
Much the same advice as from Graeme.
I use one of the 'no clean' liquid fluxes for electronic stuff that I got from Hobby Holidays to replace one of the 'felt tip pens' I used to get from Maplins. Though admit that I tend not to use a flux-cored electronic solder with it.
On white metal I use a low melt - 70 degree C - solder with a phosphoric acid flux. As a side note I keep a separate tip for this as solders with that low a melting point probably contain molybdenum that I don't really want to take up to the higher temperatures my iron can get to (450 degree max) as I don't want to breath the molybdenum vapour!
I also have a high temperature solder (245 degree I think) that is lead free and really does not mix with any other solder (guess how I found out!) so that too has a dedicated tip.
Otherwise I use 188 and 145 on the same tips without problems (and also the electroni solders as I seem to have a couple of different ones picked up over the years).
As to flux I have gone back to a home brewed Phosphoric Acid flux (10% by volume with water + 1 or 2 % isopropyl alcohol) but have got on well with Powerflow. However it's a pain to clean off even with a toothbrush and the cream cleaner as I generally forget to do it and come back to greenish kits!