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Allan Jones

Welding Brass

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I have an antique pierced brass lamp Circa 1920 and the lampshade fenial was broken and needs to be repaired. Can anyone suggest ways to repair it. I have attached a jpg image showing the item. If you need more information, please feel free to contact me at (jonesallan24@hotmail.com). THANK YOU!

LampshadeFenial6x12 100dpi.jpg

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Though I have never done it, I would think TIG welding would be the best solution.

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Yep, your options are TIG (risky, risk of melting), brazing (ditto), superglue (weak) or an epoxy like JB Weld (ugly). Any method involving heat will mean the patina will be lost. Are you sure it's brass? A lot of these are cast zinc plated to look like brass, in which case it gets even trickier.

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Depending on your steady hands, skill level and overall thickness... you could cut the threaded end off, punch, drill and tap a small enough piece of all thread all the way into the broken off piece.

Again... depending,

-Gabriel

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As a guy that has done stuff like this, be careful. Like Alan said "Are you sure it's brass?" If you come near zinc or some of the other soft castings with heat, you might quickly find you have nothing but a puddle. Don't ask how I know, but it involved the client coming with a "Brass horse" and my boss telling me to braze the leg back on.

 

The method I favor is drilling a small hole in them and pinning them together. Takes a bit of work to get both holes to match, but it can be done. Clear epoxy the joint at final fitting and it should be good as new.

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If those pieces still have a close fit when pressed together, why not soft solder it.

Jan

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I like the ideas from Gerald Boggs and grpaavola because they are best for preserving the patina and don't risk the chance of it being something other than brass.

 

Assuming it is indeed brass, the safest "hot" method I know of comes from a local smith with more years of experience than I am old (Dale Morse of Clay Hill Forge).

Small diameter brass wire fed through a MIG setup at fairly low amperage settings. Clean it up as necessary and then apply a chemical patina to blend it in.

 

I can ask him what diameter wire and amperage settings he uses if anyone is interested.

James

 

 

For the record, even a soft solder isn't automatically safe:

One of my daughters used to wear a "costume" ring I gave her, to demonstrate she was mature enough for a "real" one. Believing it to be brass, I attempted to use a 400F degree soft solder to fix a crack in the band. I wasn't even using a torch, just a standard bic lighter for a heat source, but as you can guess, the band melted a fraction of a second before the solder did.

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Also, on the soldering front, I've never had much luck getting solder (soft, such as tin/led or tin/silver alloy, or 'hard', silver/copper/zinc alloys) to flow over cracks like that. Maybe something about the surface texture? Sandblasted surfaces are much the same. Exposed surface at the break looks yellow, so likely it is brass, but the others are right about zinc and 'white metal' castings being deceptive.

 

TIGing cast brass can be dicey. Especially small castings like that, which often came out of little foundries melting whatever dross came to hand. Also, most brasses produce a fair bit of zinc fume.

 

 

Not knowing what resources you've got, I'd probably recommend Gerald's solution. Even better, if you can cram in two pins (even little tiny ones), you don't have to worry so much about twisting the top off while screwing it back in.

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Can't put my name to it, I saw this method at Chris Top's shop in Yorkshire. They were restoring the cast ironwork of a Scottish school that had suffered a fire. The pin and epoxy is one of the recommended methods for cast iron restoration, figured it work just as well with most metal.

Edited by Gerald Boggs

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Not to be contrary, but I soft solder cast brass parts like that all the time when working on old clock parts. The concerns about it being made of pot metal are valid,but I am pretty sure from the pic that that is cast brass, and not pot metal (zinc).

 

My approach would be to flux the broken area, clamp the round part in a vice with the break pointing up. Put the other piece in place, and heat with a pencil torch right at the joint. Heat the joint form one point only. (ie don't move the torch flame around) Once it gets to temp, feed a touch of solder in from the side opposite where the torch was.

 

Don't clean the surface of the part first. That original patina will help keep solder from wicking out of the joint and sticking to the surface.

 

This won't leave the orignal patina completely intact, but it will be much less noticeable than TIG welding.

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Thanks everyone for your helpful suggestions. I can verify that it is solid brass and I thought it was casted, not having much knowledge regarding these things. Did some research on the internet and I would like to run by some ideas, please feel free to respond. 1. Would brazing 56% Silver solder work or would it break when tightening the fenial ? 2. Placing each part aligning them in form sand leaving a slight gap between them and dropping melted brass in the gap and after cooling file that area to form it to the adjacent parts? Would using Cool Blue work when brazing the two parts using a brass brazing rod? Just trying to think outside the box a little and having no experience whatsoever.

 

Allan

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As long as you don't melt the finial brazing with the safety-silv 56 is stronger than the brass itself. Option 2 will not work, it'll just leave a mess. I don't know what Cool Blue is, sorry.

 

I'd go with the two pins and epoxy, myself.

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The least risky option is to make a mold off your original and cast a new one. Solder is an option if you are okay with the risk that it could go wrong. Somebody with a reasonable amount of skill could pull it off easily but, if this is a "first time soldering" job the risk is considerably more.

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The least risky option is to make a mold off your original and cast a new one.

 

This also sounds like the most fun to me! :D Requires a bit more of a set-up though. The best part is that if it doesn't work out you still have the original. I guess that is still true if it does work out too.

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Not to be contrary, but I soft solder cast brass parts like that all the time when working on old clock parts. The concerns about it being made of pot metal are valid,but I am pretty sure from the pic that that is cast brass, and not pot metal (zinc).

 

My approach would be to flux the broken area, clamp the round part in a vice with the break pointing up. Put the other piece in place, and heat with a pencil torch right at the joint. Heat the joint form one point only. (ie don't move the torch flame around) Once it gets to temp, feed a touch of solder in from the side opposite where the torch was.

 

Don't clean the surface of the part first. That original patina will help keep solder from wicking out of the joint and sticking to the surface.

 

This won't leave the orignal patina completely intact, but it will be much less noticeable than TIG welding.

Wow, great information Brian! I will have to bookmark this thread in my folder of "great information to reference if the occasion arises..."

 

That said, I have to agree with Bruce and Jerrod, making a mold and casting a copy does indeed sound fun...in our crazy fun sort of way.

James

 

Edit to add: Brian's description of heating the piece from one side and feeding the solder from the opposite side rang a bell, after hazarding a short thinking session, I figured out where I heard it before. I will start a new thread to chase that rabbit trail rather than hijack this one.

Edited by James Spurgeon

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This is where I get to have one foot on either side of the fence. I have done a lot of antique restoration for people over the years. I used to specialize in repairing or recreating odd parts that other people didn't want to touch.

 

Casting a new part would excite the blacksmith side of me, but a nicely repaired original is much more satisfying than growing a new one from the restorer's point of view.

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Silver solder should be ideal.

Braze will be too hot.

Tig will burn the zinc out = horrible porosity. Maybe there is a made tig-boffin way of tigging brass but I've never heard of it (but that isn't necessarily saying much).

But hard solder would be my first go-to, then re patinate with Tourmaline, or equivalent.

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Thank you everyone who offered suggestions on how to fix my problem, I will try to find someone who can cast a new part and go with silver solder for the original piece. I agree with Brian though, restoring the original is more satisfying and will help keep the authenticity and value of this antique lamp and the newly casted one as a back up. I will keep this thread alive and post the progress for those who would be interested in the outcome.

 

Have a Merry Christmas and Happy New Year!

 

Best wishes....Allan

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