Soldering Staintless (Grrrrrrrrrrrrr)

[82cabby]

Hi guys -

Can anyone give me some advice on soldering the seams on a stainless pan that I am making?

I have done plenty of steel work, but this is my first attempt with stainless. I have the pan made up with tabs at the corners. I welded the tabs on the outside and my intent was to solder the seams on the inside to completely seal the pan.

The problem is no matter what I do I can't get the solder to stick. I am using lead free solder from the plumbing section at Lowes. I have tried no flux, 'tinning' flux (green stuff which says it's for dissimilar metals) and the flux I use for copper pipe. I am working with a propane torch and getting the stainless as hot as the torch can.

I read all the posts and the only thing I can think of is trying to track down silver solder, which Lowes didn't carry.

Any advice???

[Batchelderd]

Don't think it will work.

[TF Maple]

There is a silver soldering stainless thread if you do a search for that. Main points were having the area scrubbed clean and maybe even emery cloth, then the right flux.

[seclark]

I think your better off using a soldering iron instead of a torch plus the right flux.I have soldered stainless many times with an Iron and had good results.The flux I've used was a liquid that I picked up at my local hardware.At least thats what works for me.What guage stainless is it? Stan

[KenWP]

You have to rough it up some what for both edges. Then use the right solder for SS lead free and then with a low torch get it hot but not to hot and it should stick. if you don't roughen it up you will not get it to stick.
The old irons work good also and if your lucky like me you find a old large electric soldering iron that works also. I soldered on joint with one of those tiney butane torches. You need to have the metal in a warm room and such as they don't put out a lot of heat.

[maple flats]

Don't use a torch. Much easier to solder thin SS with an iron. Use sal ammoniac for fluxing the iron. Use a flux labeled for SS and silver solder. Do not use emery cloth, brush only with a SS brush. In the other thread about soldering SS I give several points to follow. It works best to have a heavy soldering iron, either electric or one heated by a torch. In shops where they solder tin or ss routinely they use a propane fired oven of sorts. It is an open flame with a metal support where 2 or 3 iron rest with their heads in the flame. As a head cools they put it back in and use the next. With a single iron you will have a harder time time if it is not a good electric one. The work area will cool too much between heatings.

[82cabby]

It's 16ga stainless. I found some silver solder but it didn't work any better. The largest soldering iron I have is a soldering gun which works well for larger electrical projects, but I don't know if it has the mass needed for this.

I am going to make a run to the hardware store and see if I can find solder or flux that is specific for stainless steel.

[flooder]

you welded the outside why don't you weld the inside?

[ronr]

Clean your joint well of oil etc. with a non residue cleaner, something like alcohol. I then hit it real lightly with a scotchbrite pad. You need a real big electric iron or the old time copper irons you heat with a torch.

My favorite solder is Lenox Sterling lead free, have tried others I find the Lenox works best for me, got mine at Lowes. You will need special stainless steel flux; the stuff I have is a clear liquid I apply with a flux brush. It takes very little, just a thin film.

I like to preheat the area with a torch from the back side, not the solder side, and then have at it with the iron. When it’s right it will flow into the corner real nice.

[Peepers]

I'd vote for welding too. I tried soldering the drain holes closed in my old kitchen sink last year and no matter how good I cleaned and fluxed it seemed impossible to get a good solder joint all the way around. I have soldered a lot of plumbing, electrical and stained glass over the years but have never seen solder behave like it did on stainless. I hear of a few people having success but I hear of a lot of folks having problems too.

I think there is a very fine window between having the stainless hot enough for the solder to melt/stick and having the stainless too hot where it oxidizes and solder won't stick.

Either way good luck and if you get it to work please post your success story!

[Peepers]

So Ronr do you drip some solder on from the front side using the iron then heat from the backside gently until the solder sucks into the joint then melt more on the front into the seam with the iron?

Maybe that technique with the right solder/flux combo is the key. I had flux that covered stainless but was trying to heat from the front. Maybe I burned my flux off or something.

I was also doing it in a cold garage so keeping it at the right temp long enough to get the job done was tough too.

[82cabby]

On a return trip to lowes, I got bounced through a couple of guys before they found one who even knew what I was asking. He told me I had to "braze it with silver solder and an acetaline torch, propane or MAP gas wouldn't be hot enough". And, no they didn't carry silver solder. Luckily I found some in my plumbing box. I ended up getting a couple of different types of fluxes and solders.

Back at home, I lined up every solder and flux I could find and did some testing on a scrap. The only combos that worked were silver solder or lenox lead free with lenox sterling water soluable flux. Both with a real low torch. They did a halfway descent job of sticking. I am going to call a specialty plumbing supply shop tomorrow and see what they have for flux.


I have been debating welding inside, but I don't think I can do a decent job of grinding down the welds deep in the corners. I can't get in there with an angle grinder and an abrasive stone on a die grinder would take forever.

I will post pictures when it's done. But frankly its a little embarassing! Not my best work.....

[ronr]

The torch is just to preheat the metal, more important with heavy gauge stuff than thin. I use an old time copper iron you heat with a torch. This is a square slug of copper about 1 inch square and 3 inches long attached to a 8 or so inch long steel shaft with a wood handle, like a slug of copper on the end of a screwdriver. The end comes to a four sided point.

You heat this up rub it on a sal ammoniac block or other flux and tin it well. Then reheat, place in joint and feed solder in on the very tip while drawing along the joint slowly. Go a bit and reheat. You can also rework previously soldered areas with it.

The preheat is only because the iron only stores so much heat and can't heat a large area without cooling too fast. The preheat is only a few hundred degrees, well below the melting point of solder.

[KenWP]

What ever you don't try and braze it as brazeing is not lead free and Acet. is way to hot and will burn the SS anyways. I tried a propane torch and it took way to much solder as it kept melting off on me. The large electric worked well and if I had any way how to heat the big irons I would try those also. I bought two bottles of flux and used part of one but used way to much solder before I got finished.

[82cabby]

Thanks for the replys!

I can't braze it since I don't have the set up for it, so that's not a consideration. I will try the soldering tomorrow and if it chews athrough too much solder..... I guess I will have to come up with a plan B!

I know the copper - torch heated soldering irons you all are talking about. Tough to put my hands on one though!

[b_mclarty]

[QUOTE=ronr;100678]Clean your joint well of oil etc. with a non residue cleaner, something like alcohol. I then hit it real lightly with a scotchbrite pad. You need a real big electric iron or the old time copper irons you heat with a torch.

Thanks for the tips ronr. I've been using an 165 watt electric soldering iron with ESAB 430 soldering and Duzall liquid flux. Even though I thought that the stainless was clean, I was getting mixed results. I tried your suggestion of cleaning the metal with alcohol and scuffing a little with scotchbrite and the difference is remarkable. I'm getting much better results now.

Thanks again!

[82cabby]

Alright so here is another rookie question on this topic. I think I can make my own 'old school' style soldering iron... My question is can I make the working end out of brass? I happen to have a hunk that would work.

[KenWP]

Yes take the brass and grind the end to a 4 sided pryamid point. Attach a handle by drilling into the end and installing some kind of steel rod attached to a wood handle. It's best to have two of these so ones alwasy hot in the fire. For the type of work we are doing try to be a big a possible with out being unweildy. Should work fine.