Silver Solder Stainless?

[Stevedore]

I have a small stainless steel kitchen measuring cup that I'd really like to repair. In the attached pic, you can see that the 3 tiny spot welds have failed.

It may seem silly, but this cup is one of a set my mother gave to my wife about 50 years ago, and although my wife has several other sets, this one has sentimental value.

So my question is: Am I likely to be able to silver-solder the handle back on to the cup? I've used silver solder in the past with a Bernz-o-Matic torch, but never on stainless. Don't even know if it'll work.

Comments, suggestions? Thanks!

 

[rlitman]

"Silver" solder is mostly nickel. Nickel is not something you want in contact with food.

I'd probably try to TIG it, but it WILL look like a mess afterwards.

 

[The Cobbler]

I had good luck silver soldering a stainless steel pot handle bracket that broke off
it doesn't look pretty, but it works
I wasn't aware of nickel being an issue. stainless steel has nickle in it?

 

[MoonRise]

Usually I agree with rlitman, but not in this case. Well, I agree that TIG (by someone competent) would be a #1 preferred choice to fix that.

The 'silver solder' that I am aware of would be something like Harris Stay-Brite. 4% silver and 96% tin. No nickel at all (not counting trace amounts).

Another would be Lucas-Milhaupt Silvabrite. Again, 4% Ag and 96% Sn.

https://www.lucasmilhaupt.com/EN/Products/SILVABRITE.htm

Both are food safe.

Want to move up (in temperature) from "soldering" to "brazing"?

Harris Safety-Silv 56, food safe. 56% Ag, 22% Cu, 17% Zn, and 5% Sn.

Lucas-Milhaupt Silvalloy 560. Same composition. Food safe.

https://www.lucasmilhaupt.com/EN/Products/SILVALOY560.htm

And there are other possible choices.

Lucas Silvalloy 401. 40% Ag, 30% Cu, 30% Zn. Food safe.

https://www.lucasmilhaupt.com/EN/Products/SILVALOY-401.htm

and more choices.

Yes, 'silver solder' can (usually) work on stainless steel. Double check the alloy composition or call/contact the alloy company to verify if what you are thinking of using is indeed food safe.

The food-safety checking ALSO applies to the flux you will use.

And you WILL need flux to successfully solder or braze stainless steel.

Note also that the 'silver solder' or silver brazing alloys are rather expensive. If you have to go and buy some. Safety-Silv 56 plain (not flux coated), $21 - $26 per troy ounce, depending on wire diameter.

example:

https://weldingsupply.com/cgi-bin/roundup.pl?buynow::::5631~~~~700

And then you have to get the required flux.

Clean the parts well with soap and warm water, dry well. Clean again right before soldering/brazing with solvent cleaner to make sure there is no grease or oil (careful with the solvents!). Flux the faying/mating surfaces, gently clamp the parts together, apply heat, apply soldering/brazing filler metal, let cool. Clean flux residue well. Clean (more like scrub) the heat discoloration or use appropriate stainless steel cleaner(s).

Wait a minute. It look like the spot welds pulled right through the cup wall.

You're in Morris County? I can't TIG it (no TIG machine ), but I could stainless MIG it back together for you. Clean up and smoothing/grinding/polishing the weld beads would be up to you.

 

[MattT]

"Silver" solder is mostly nickel. Nickel is not something you want in contact with food.

A high silver % food grade solder/braze is what the OP needs. Done right the repair will be barely noticeable.

https://www.harrisproductsgroup.com/en/Products/Alloys/Brazing/High-Silver/Safety-Silv-56.aspx

 

[rlitman]

Usually I agree with rlitman, but not in this case....

No offense taken. We're all good.

As I see it, the tin based silver solders are a no-go. With the correct acid flux, and a lot of luck, there is a slim chance that you can actually get them to stick to stainless, but even if you manage that, the required tensile strength and ductility just aren't there. The first time you dip it into your sack of flour, it will rip. I suppose if you want a cosmetic fix for a wall-hanger, it might be a good option, but remember that if you attempt a repair with one soldering method, it will likely prevent any future success with a different method, because the joint is now contaminated with an alloy that only works well in one temperature range.

As for the solders that are actually made with silver...

A high silver % food grade solder/braze is what the OP needs. Done right the repair will be barely noticeable.

https://www.harrisproductsgroup.com/en/Products/Alloys/Brazing/High-Silver/Safety-Silv-56.aspx

Yeah, I guess, again, with the right flux, I think this will have a chance. I've just never seen food safe "silver" solder on the store shelf. Maybe I'm shopping at the wrong places, but even the stuff that's mostly silver too often has other nasties in it like cadmium.

Anyway, good luck and be careful what you use.

 

[Stevedore]

Thanks for the replies. Most of the "silver solder" I have is of unknown composition. Several pounds of various gauges that I "acquired" when a shop was closing where I worked ~40+ years ago. All I know from various repairs & fabrication is that I need to get the work red hot for it to flow properly.

For this little project I should probably find one of the products recommended above.

@MoonRise: Thanks for the offer, but I can't sleep at night unless I do things myself to whatever extent possible! I'm in Long Valley, BTW.

 

[The Cobbler]

another option would be drill it & use stainless screws or pop rivets

 

[rlitman]

another option would be drill it & use stainless screws or pop rivets

I like the way you think.

Most pan handles are attached with rivets. All of the good ones I can think of are. The rivets are usually aluminum, though they often use stainless steel caps to keep the bare aluminum out of the interior.

Stainless pop rivets should be pretty easy to use here, and should look ok. Solid rivets would make a better than factory fix, but are pretty difficult to apply.

A stainless semi-tubular rivet might be the ideal option. Like these:
https://www.ebay.com/itm/Stainless-...ets-3-32-X1-4-OHTR332140-100pcs-/321090124904

 

[MoonRise]

Long Valley, eh? That's only 1-2 towns away from me.

My offer still stands. Bring it to me and I'll MIG it back together for you.

You'll still have plenty of grinding and polishing to do if you want the weld beads to 'disappear' and to remove the inevitable heat tinting, so don't think that you won't have some work to do.

btw, you'd still have to do the clean up if it were TIG welded.

Unknown vintage and unknown alloy 'silver solder'? I would NOT use that for a food safe repair. Some (a lot?) of the old(er) 'silver solder' stuff DID have cadmium in the alloy mix. And you really-really do NOT want that in food. (or to breath in any vaporized cadmium)

Pop rivet? Way too 'ugly' with the back end of the shank hanging out.

A solid or semi-tubular all stainless steel rivet could be pretty good. You would have to 'roll' the tubular end of the rivet to form the head or roll/peen the shank of the solid rivet to form the head.

https://www.valleyfastener.com/semi-tubular-rivets.html

https://www.rivetsonline.com/documents/catalog pages/semitubular rivets.pdf

https://www.rivetsonline.com/solid-stainless-steel-rivets#1

https://www.rivetsonline.com/documents/catalog pages/solid rivets.pdf

As to the strength, I repaired a stainless measuring cup/scoop via brazing years ago. Like the OP, the spot welds failed. My repair has held up, knock on wood. I used a 'standard' low-fuming bronze brazing rod IIRC (it's been literally years since I did the repair). Not an invisible repair, but it has held up just fine.

The brazing fillers in this 'category' have a strength of around 60 ksi. The bronze or the silver brazing filler. Plenty strong for steel or stainless steel.

YMMV and all that.

 

[matt_i]

I feel like Tig weld is best because the heat can be concentrated into a small area.

The silver solder is going to have to get a larger area hot with a flame (double thickness of metal, almost like sweat-soldering a Cu pipe joint).

More heat = more discoloration.

The solder-y metal-wetting formulations would leave the cleanest joint, welding might have a burr or other little flaw in it that would have to be metal-finished out.

Mig weld? Are you running around with (have sitting around) a spool of stainless steel wire?

 

[MattT]

I've just never seen food safe "silver" solder on the store shelf. Maybe I'm shopping at the wrong places, but even the stuff that's mostly silver too often has other nasties in it like cadmium.

I wouldn't expect to find any high % silver alloy on a store shelf. Small and high value it'd be flying off the shelves.

another option would be drill it & use stainless screws or pop rivets

A conventional pop rivet could leave a hiding place for unwanted biology experiments. This thread is turning into 1,001 ways to die

You can get blind pop rivets which should be safe but wouldn't look very good.

https://www.hansonrivet.com/rivets/blind-pop-advel-rivets/closed-end-blind-rivets/

 

[MoonRise]

Mig weld? Are you running around with (have sitting around) a spool of stainless steel wire?

Why, yes I do have 308/308L stainless wire. And the tri-mix gas to go with it.

How else am I going to weld MIG stainless steel 304 things together properly?


Well, other than a TIG and some pure argon gas and the stainless steel filler.

To misquote Calvin (of Calvin and Hobbes, not Calvin the theologian):

I have a welder! I can put things together!

 

[harley jim]

Tig weld it.
I ran a fabrication shop for years. We did the majority of restaurant remodels for various contractors and welded many pots. All stainless repairs we did were tig and it works well. Sometimes a couple of well placed plug welds can be easy to finish and hide.

Sent from my SM-A102U using Tapatalk

 

[oldmachinenut]

Spot weld

 

[exmaxima1]

I wasn't aware of nickel being an issue. stainless steel has nickle in it?

+1
I had no idea, especially since the common SS like 18/8 is 8% nickel. I thought it was only an issue for persons that are allergic to it. That's why some people can't wear cheap earrings with nickel wires, whereas most people can

 

[harley jim]

Why, yes I do have 308/308L stainless wire. And the tri-mix gas to go with it. [emoji38]



How else am I going to weld MIG stainless steel 304 things together properly? [emoji38]_hitti





Well, other than a TIG and some pure argon gas and the stainless steel filler. [emoji38]



To misquote Calvin (of Calvin and Hobbes, not Calvin the theologian):



I have a welder! I can put things together!



[emoji481]

I like your answers sir.[emoji106]

Sent from my SM-A102U using Tapatalk

 

[danski0224]

I have a small stainless steel kitchen measuring cup that I'd really like to repair. In the attached pic, you can see that the 3 tiny spot welds have failed.

It may seem silly, but this cup is one of a set my mother gave to my wife about 50 years ago, and although my wife has several other sets, this one has sentimental value.

So my question is: Am I likely to be able to silver-solder the handle back on to the cup? I've used silver solder in the past with a Bernz-o-Matic torch, but never on stainless. Don't even know if it'll work.

Comments, suggestions? Thanks!

You will be able to solder that back on using something like Harris StaBrite #8 and a liquid flux for stainless steel.

The problem will be controlling where the solder goes, and the appearance of the repair. Of course, detailed sanding/filing can clean it up.

Hard rivets made out of stainless steel will be difficult to install (forming the end). Hard rivets made from copper will be less difficult to install (forming the end), but equally difficult if you have not used them before.

Wire feed welding will probably result in disaster. Very easy to blow a hole in the paper thin stainless cup. The handle is probably 2 or 3x as thick.

Even TIG welding that will require skill... or at least someone that does it on a regular basis.

I fixed one much like that several years ago, might even have been the exact same manufacturer. The handle looks the same. The individual was happy with the soldered repair. I didn't even attempt to MIG it, and was less than confident about TIG. The cup is really quite thin.

 

[donmillerx]

Small stainless rivets, a hammer & a couple minutes.
Try a test piece first.

 

[Roju1985]

https://www.ebay.com/itm/Silver-Sol...361329?hash=item23bc153331:g:gGoAAOSwPrdb7jrv

pair that with harris flux and you're good to go.