beginner's questions about soldering

The older fluxes contained a high amount of metal ions - zinc IIRC. This plated the metal and the flux that was a chlorine based etched the metal for the plating process to keep it from oxidizing again.

I think a lot of this has changed through the years with the water based fluxes and get the lead out solders.

for Stainless steel - HCL 1 part , zinc chloride 1 part. for cast iron Zinc Chloride 15 parts, sodium chloride 3 parts, ammonium chloride 2 parts Al Bronze and Si Bronze - HCL 1 part, zinc chloride 1 part, water 4 parts Zinc base die casting - not much hope - I suggest electro or flash plating of copper then solder on that.

Soldering and Brazing by a.r. Turpin - U.K. printing - ISBN 0 85344 098

0 Nice little book.

Naturally the HCL is hydrochloric - you can use swimming pool acid - Muriatic a lower grade from lab qual.

Martin

I've heard that pure TIN is used on Al - then once it is integrated, other solders can be added to it.

Martin

I have Electronic chassis in the shop both Al and Steel. The chassis is the ground (plane :-) ) and there is a common big ugly solder spot inside. These were audio and high quality in nature.

Martin

I wonder if the alloy contained gallium or indium?

Tim

-- "That's for the courts to decide." - Homer Simpson Website @

1 you can solder alumimum if you use the right type of solder in fact you can solder alumimum to copper ( as used in some car alternators ) you can solder ferrous metals 2 ( they used to use solder as body filler in car bodies before plastic fillers (bog) 3 you can braze alumimum to zinc all with perfect results

I'm not convinced. I think you guys may be confusing soldering to zinc with soldering to steel, but I'll admit I don't know much about it.

So why not ? Sounds like you're using the wrong flux.

Baker's Fluid / killed spirits / zinc hydrochloride (take hydrochloric acid - dissolve an excess of zinc in it) works fine as a flux for steel. That and either a gas heated iron. or a large electric one.

Strip any plating off first too.

-- Die Gotterspammerung - Junkmail of the Gods

While soft soldering stainless is a bit tougher, because of the extremely low thermal conductivity, it can easily be done with the correct active flux. I use "Duntons" liquid stainless flux, which works well except the mist and fumes that come off are a bit corrosive.

I've found that the key to doing a good stainless joint is to carefully pre-tin the part. This really takes less heat than is imagined - the stainless has such low thermal conductivity that even large thick parts can be surface tinned with a small iron or gun. The part will heat locally and the solder will wet the surface nicely.

One common mistake is using too much heat, and overheating the flux, and burning it off before the solder has a chance to wet down. Also using rosin cored solder is not the best, as the rosin for this application is not really a flux, but a contaminant that the acid flux has to overcome before it works properly.

Once the stainless part is tinned properly, once, it can be sweated without the use of stainless flux - ZnCl or rosin flux can be used to attach a tinned stainless part to copper brass or steel.

Because the Silver-Tin solder (eutectic 151 is my favorite) is so much stronger, and does not contain any rosin, and has a low vapor pressure (no lead) it is my favorite for doing the odd vacuum system job where stainless parts have to be soft soldered.

Jim

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One of the problems with indium as a solder is that the oxide is water soluble. So if a joint is likely to get wet, it will oxidize and the oxide will wash away, and then the joint will oxidize more, and eventually the joint will crumble into dust.

It may be that some of the indium alloy solders have the alloy components chosen to eliminate that problem - but it does show up when using indium as a low temperature solder in electronics work.

Jim

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No, it's done with tin/lead solder. It was used to make a lot of electronic hardware during WWII. You probably could look it up.

Ed Huntress

I think that most of the people here who have had difficulties soldering one material or another are looking at it from the wrong angle. It isn't the solder. It's the surface preparation and fluxing.

Ed Huntress

Jim,

I agree whole heartedly. Soft soldering steel and/or stainless steel is very easy to do. I commonly solder stainless with great results.

I use Harris Stay-Brite 8 Silver Bearing Solder and Harris Stay- Clean soldering flux for all metals other than aluminum and I use Harris Stay-Clean Aluminum flux for aluminum soldering. The solder is the same.

You can check it out on the Harris website:

- just follow their link for soldering alloys.

PJ - (not affiliated)

Here's a quote from Kester's flux pages:

==========================

For soldering aluminum to copper, to aluminum, and to stainless steel. The chemistry of Kester #2600 Aluminum Flux activates on metal surfaces at

350-550°F. Excellent for aluminum to copper soldering when used with a 91% tin / 9% zinc alloy, 390°F m.p. Kester Part # Description Packaging 63-0000-2600 #2600 Aluminum Flux 4 L / 1 Gal Jug #2600 Aluminum Flux 20 L / 5 Gal Jug #2600 Aluminum Flux 200 L / 53 Gal Drum

Steel and Stainless Steel Torch Soldering #715 For soldering copper, nickel, and most mild steel torch soldering applications such as in plumbing.

#817 For efficient soldering of nickel-chrome and stainless steel with a soldering torch or iron.

==============================

Tinsmiths have been soldering steel and iron for at least 100 years using zinc-chloride fluxes. That's what body repairmen used to use (a few still do) for solder-filling of auto body panels -- plain, low carbon steel. The "lead" filler used in premium car restoration work actually is a lead/tin solder that's far from the eutectoid alloy percentages, which makes it pasty so it can be spread with a paddle. You "tin" the body steel first using the same solder. It wets beautifully if you have your technique down pat.

Active fluxes such as hydrochloric acid and zinc chloride are not common items in hardware stores today, and a lot has been forgotten about soldering among many metalworkers. But the range of metals you can solder covers almost everything we use, if you know how to do it. The information is still available. You just have to go looking for it.

BTW, in my first metalshop class, in 6th grade, we had to make our own zinc-chloride flux and sweat-solder a "tin" cup (plain carbon steel, although a few lucky guys got to use tinplate -- they ran out before my project came up, and I had to use plain oiled steel sheet), so that it didn't leak water. Oh, and we used soldering coppers that you heated in an oven. No electric soldering irons were allowed. Yes, that was a very long time ago.

Ed Huntress

Thanks for the information! - Now I'll have to dig it out of my shop desk and put it in a vault! I have some made by Ultra-Pure for Doping silicon in the 'old days'. It was for diodes - a carbide plate drilled with hundreds of holes - shake over - fill each hole - put into oven run to a high temp C in a xtal oven..... slice, dice and add leads.

Hum - just in time for a Christmas tree - hum...

Martin

I do both routinely. Just buy the right solder.

I like Harris Staybrite, a low-temp silver-tin alloy for steel, stainless, brass, bronze, copper and every other metal I've tried it on other than aluminum. I don't recall the working temp but it's under 500F. A soldering gun or iron or propane torch works fine. It readily wets any of the metals I mentioned and it's quite strong

-- 24,000 PSI IIRC. It would be good for art work because it's color match with steel and stainless is very good. Flux is ordinary tinner's fluid.

For aluminum solder that works beautifully, , two sources: Aladdin and TinManTechnology. ESAB #31 also works well. It's closer to brazing, but the stuff works like magic on thin aluminum, wets and flows almost like silversolder does on brass. I've made joints with thinwall tubing thru thin plate by fluxing the joint, placing a preform ring of solder at the joint and heating the work until the solder melted and the joint made itself with a nice fillet. I have photos if you doubt it.

It must be used with companion #31 flux. Both are available from W.W. Grainger.

Stainless steel type 304 and 316can be silver soldeereed using a high-temperature flux, but beware - the silver solders I have used contain some zinc, which embrittles stainless at red heat, so to make thin stainless bits join together, I had to work quickly and quench quickly, before the zinc could work its way in between the steel crystals. Any interest?

-G.H.Ireland

I'd be interested in learning more about this. Wonder what kind of solder? Lead, silver? Sounds interesting.