what flux for white metal?

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jon price
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what flux for white metal?

Postby jon price » Tue Jan 17, 2017 5:39 pm

looked at the soldering white metal thread, doesn't really help. What flux is best for white metal. Can I get away with the pluimbers paste I use for brass and nickel silver?
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David B
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Re: what flux for white metal?

Postby David B » Tue Jan 17, 2017 5:57 pm

I use phosphoric acid - Carr's yellow. Also use it for brass and nickel silver. The only time I use a different flux is for electrical soldering.

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grovenor-2685
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Re: what flux for white metal?

Postby grovenor-2685 » Tue Jan 17, 2017 6:43 pm

Regards
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Will L
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Re: what flux for white metal?

Postby Will L » Tue Jan 17, 2017 8:58 pm

jon price wrote:.... Can I get away with the plumbers paste I use for brass and nickel silver?


Definitely not you need Phosphoric Acid. But then I wouldn't use plumbers paste on Brass either.

As a bonus, if you use a fair bit of the very liquid Phosphoric acid flux, the white metal wont melt while the flux, which is mostly water, boils away as this keeps the temperature at about 100oC. When it stops hissing remove the iron.

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Jol Wilkinson
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Re: what flux for white metal?

Postby Jol Wilkinson » Tue Jan 17, 2017 9:33 pm

6% Phosphoric acid. Higher percentages or other stronger fluxes can leach out impurities in the w/m making it go black and more difficult to solder.

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jon price
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Re: what flux for white metal?

Postby jon price » Tue Jan 17, 2017 10:25 pm

Thanks for the expert advice. Havn't had much success with phosphoric acid flux before, it runs away before I can get the iron in, but I'll give it another go. 250ml of 81% for just less than £6 will give me about 12 litres of 6% so I should have plenty to practice with.
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David B
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Re: what flux for white metal?

Postby David B » Wed Jan 18, 2017 10:00 am

jon price wrote: Havn't had much success with phosphoric acid flux before, it runs away before I can get the iron in, but I'll give it another go.


How much flux are you putting on? You need very little, just enough to wet the area. I bought a 250ml bottle (of Carr's yellow) back in 2009 and still have 2/3rds of the bottle remaining. I have made a lot of white metal kits in the meantime.

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jon price
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Re: what flux for white metal?

Postby jon price » Wed Jan 18, 2017 11:25 am

David B wrote:
jon price wrote: Havn't had much success with phosphoric acid flux before, it runs away before I can get the iron in, but I'll give it another go.


How much flux are you putting on? You need very little, just enough to wet the area. I bought a 250ml bottle (of Carr's yellow) back in 2009 and still have 2/3rds of the bottle remaining. I have made a lot of white metal kits in the meantime.


I should have said "evaporated" not "runs away", but I'll give it a go anyway. The 250ml of 85% cost less than half what it would have cost to get the Carrs yellow including postage, so even though it will make an insane amount of flux it is a better buy. I can make it up in a little squeezy bottle which has a thin tube to aply to exactly the right place.
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Jol Wilkinson
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Re: what flux for white metal?

Postby Jol Wilkinson » Wed Jan 18, 2017 3:26 pm

Don't forget to dilute it with purified water, which may increase the cost slightly. A little bit of wetting agent also helps.

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Paul Willis
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Re: what flux for white metal?

Postby Paul Willis » Thu Jan 19, 2017 7:41 am

jon price wrote:looked at the soldering white metal thread, doesn't really help. What flux is best for white metal. Can I get away with the pluimbers paste I use for brass and nickel silver?


I'm fairly promiscuous. I just use whatever is in my dropper bottle with the syringe needle top. The current mix is of Carrs' Green and Red label although I couldn't tell you in what proportions. I needed to restock recently so bought another bottle of "something" from Phil at Hobby Holidays and that will just be decanted into the same bottle ;-)

I'm probably a heathen as I use the same flux for whitemetal, brass, nickel silver, phosphor bronze and anything else pretty much which comes along. The only two exceptions for soldering are:

- steel, where I use the *really nasty* Brown Label Carrs stuff. I hate using it as you can almost see it corroding everything as soon as you take the cap off the bottle (and mine has actually eaten through the supplied plastic cap previously). However in some circumstances it is necessary and I make sure I clean up scrupulously.

- electrical work, where I use a proper electrical solder with a core of resin flux. I don't know the alloy composition, but it came from one of the electrical component suppliers rather than our end of the hobbyist supplier spectrum.

I really wouldn't use a plumbers' paste, and I haven't heard of anyone successfully using it. It strikes me it wouldn't "boil off" in the way which helps solder flow on whitemetal. However there is no doubt there is *someone* on the esteemed Forum who is using it successfully!

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Albert Hall
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Re: what flux for white metal?

Postby Albert Hall » Thu Jan 19, 2017 8:48 am

Carr's nasty Brown Flux is predominantly neat phosphoric acid - a very concentrated version of the Yellow Flux which is around a 12% solution. It does work on steel but is specifically aimed at 'difficult' metals like stainless steel. I first came across it when assembling Masokits wagon suspension springs. Like any acid it needs to be treated with respect and 'neutralised' afterwards. It can be diluted but good practice is to add acid to water and not the other way round. I've never soldered white metal so can't comment.

Roy

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Re6/6
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Re: what flux for white metal?

Postby Re6/6 » Thu Jan 19, 2017 10:33 am

Flymo748 wrote: However there is no doubt there is *someone* on the esteemed Forum who is using it successfully!


Indeed Paul, l've been using it successfully for years! I have a mental aversion to 'acid' stuff after seeing a beautiful G1 King in Brewsters Plymouth shop falling to bits due to flux corrosion. Mr Brewster himself told me never to touch the stuff. l thought that as he was in the solder business he would know.

In later life of course l've seen many excellent modellers use it with great success ...so each to their own...!

For whitemetal l use 'Jenolite'. I now await advice to the contrary!
John

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jon price
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Re: what flux for white metal?

Postby jon price » Thu Jan 19, 2017 10:53 am

I was introduced to plumbers paste forsoldering etched stuff at Missenden. In the usual way a dealer gave me a free sample to get me hooked. It has worked fine for me and helps to keep the tiny blobs of solder in place before heating. (the guilty party at Missenden was Mr Tatlow)
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John Bateson
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Re: what flux for white metal?

Postby John Bateson » Thu Jan 19, 2017 2:22 pm

While I also think (and know) that standard flux for brass should work, tinning the brass first, I also use so-called 'plumbers paste, i.e. Nealetin, available from Hobby Holidays at either 80GM (£9) ar 250 gm (£25). One tub has kept me going for many years. Applicable by syringe or on the end of a cocktail stick.

The syringe offered lower down in the list is, I believe, a simple medical syringe containing a small amount of slightly different spec paste. Do try to avoid this, it is expensive.
Syringes are available from Amazon for a pack of 5, about £3. As well as 100 pack of plastic pipettes for use in painting etc. for £3.

Of course, if using separate flux, use also an open window or the mask that Flymo recommends at http://www.screwfix.com/p/dr-ger-p3-chemical-half-mask-set/39216.

Pontification over.

John
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steve howe
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Re: what flux for white metal?

Postby steve howe » Sat Mar 17, 2018 8:24 am

Can anyone with chemical knowledge advise if Carrs Yellow Label flux is a substitute for Eames 40? I've been using Eames 40 for a long time but my last bottle is getting low (pity, I only bought it in about 1985... :? ) and I do use it, as David says, on pretty much everything apart from electrical wiring.

Steve

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Jol Wilkinson
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Re: what flux for white metal?

Postby Jol Wilkinson » Sat Mar 17, 2018 8:48 am

I don't know the composition of Eames flux but a less aggressive flux is better with w/m. Stronger fluxes can leach out impurities in the metal, blackening the surface and making it more difficult for the solder to bond.

I use LRM 6% Phosphoric acid flux on w/m and 12% on brass and n/s. Those who like to practise economy could buy just 12% and thin some down with water as required!

Carrs are now part of PPP and their website shows Red and Yellow as being suitable for w/m as well as brass and N/S, although I always thought Red was for w/m and yellow for brass.

Philip Hall
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Re: what flux for white metal?

Postby Philip Hall » Sat Mar 17, 2018 10:29 am

I too used to use Eames 40; the local model shop recommended it (mind you apart from Fluxite it was all they had I guess) and used it very successfully until I changed to a phosphoric acid flux, which seemed to me to be the same sort of thing. At least it smelt the same and made you cough and sneeze when the fumes went up your nose, but that was a long time ago before we got wise to such things and opened windows.

The present stuff I used was a home brew that Peter Swift and I made up a very long time ago and we have been gradually getting through, and this is a dilute phosphoric acid/distilled water concoction, I think about 10%. I think there’s a drop of washing up liquid in there as well as a wetting agent. I use it for everything except electrical work.

Philip

martin goodall
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Re: what flux for white metal?

Postby martin goodall » Sat Mar 17, 2018 11:27 am

I have always used phosphoric acid for soldering whitemetal and 70 degree solder wiped down the joint with a miniature low voltage soldering iron, but I long ago finished my bottle of EAMES 40 flux. This product was simply a weak solution of phosphoric acid.

The phosphoric acid flux usually available nowadays appears to be roughly double the strength of the old EAMES product, and is formulated for soldering brass (and nickel silver), but is equally useful for whitemetal. If you wanted to reduce the strength for whitemetal soldering (although I don't see why this should be necessary), you could just let it down 50:50 with water - distilled water if you are fussy.

I am told that if you are unable to find a phosphoric acid flux, you can use a bottle of cola (!) - which contains phosphoric acid.

You can get a whitemetal kit apart by pouring boiling water over it. The boiling point of water (100 degrees C) is somewhat above the melting point of the solder, but below the melting point of whitemetal. But you then have the problem of removing the residue of the (re-solidified) solder from the whitemetal castings. I have done this only once; it's a desperate measure, but not impossible to achieve.

[One item of useless information: EAMES was not a surname; it was an acronym that stood for "Electrical And Model Engineering Services" (hence the fact that the name was correctly written or printed in capital letters).]

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Re6/6
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Re: what flux for white metal?

Postby Re6/6 » Sat Mar 17, 2018 7:50 pm

I've used 'Jenolite' rust remover which is available in car accessory shops.
John


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