Help-solder/gold remover needed

[pilkguns]

I just got a piece back from heat treating that had gold inlays in it. Had being the operative word here. This is strange thing, but I have pink, green and yellow gold inlays in it and some have chosen to stay exactly like I sent them off, others have bubbled up like a volcano, cleaning out their cavity for the most part and made a layer of thin gold across the surface that is on there very hard. It will not peel off, and cuts off very hard. Getting it comeplety out of the engraved grooves for scroll is a nightmare. No rhyme or reason for which ones stayed and which did this. The pink gold does have a copper backer that was soldered to it so it seems the solder has thinned the gold and made it a massive welded on blob. Anybody with any ideas what might remove this? Aqua Regis? I wonder if I have what it takes to make some up to try? Other suggestions??

 

[Dmitriy Pavlov]

I'm sorry. I am afraid, that a gold from a steel can be removed only mechanically. Any an acid or a mixes of acids as Aqua Regis will dissolve a steel more quickly, than a gold or a gold alloys, like Pink or Green Gold

 

[ED DELORGE]

Hello Scott, I can relate, about two years ago I did a big job and decided I was going to electro plate the action (Ruger #1) myself, instead of sending it to my usual platter who has never failed me. Well the platting went pretty good except for about two little bubble spots, so I thought I would just strip it off and plate it again. That is when it went south. The acid solution got under the plating and ate up the action beyond restoration. So, I had to buy another action an start over. Of course I had to refit the barrel and refit the stocks that I had made to perfect fits but now were not as perfect. It was a big loss, but the customer was kind and patient.

Ed Delorge

 

[pilkguns]

Dmitry, I sort of thought this, but at the same time I was thinking you could use Aqua Regis or something similar to clean gold from a clogged file? Did I make that up?

 

[Powderhorn]

Pilkguns:
It sounds as though you might of got some Heavy gold plate material, and depending on how it's made, Double sided plate, or single over a base metal. It may have been the base metal that was the culprit in the blueing tank. It would cause the blueing solution to act as an electrolyte and cause a plating of metal to your surface. As to getting it off, I would suggest that you go with mechanical only, as stated before anything that would etch it off would also eat the steel. I had a thought about trying a plating setup, but that would still eat the steel, because if you had a solid area, as soon as it etched through, it would immediately attack that area more than the gold. Good Luck

 

[Dmitriy Pavlov]

Scott, My apologies for my English. If I understood correctly, Aqua Regis is mix from HNO3 and HCl. This is agressivest mix of an acids, that dissolves gold upper then 8K (around 25%). I'm sorry, but I'm sure, in the time then that needs for dissolves a gold your steel will be irrevocably damaged. I know a method for cleaning a files with sulfur acid (H2SO4), but it dissolves a steel and give a possible to remove a golden scrap from a file.

 

[Mike Cirelli]

I agree with Dmitriy Aqua Regia will definitely damage the steel. It sounds like what happened is the solder used on the gold broke loose when heat treated. Gold becomes very brittle if you heat it and try to work it. My thoughts are if you can heat it and pick it out as you heat it, it may crumble out. Why did you use a ply and what did you solder it together with.

 

[Dmitriy Pavlov]

Scott, I have an idea. You can try contact with a jewelry work shop, what have a Laser Welder. May be it is possible to weld a pits on your inlay.

 

[pilkguns]

Dmitriy, your english is fine, its my knowledge of the subject that is hazy, along with some desperation/frustration mixed in.

Mike, normally when doing a hard inlay into steel such a pink gold or steel into steel, you solder a copper backer to make it adhere to the teeth. I am not sure the solder used, I did this years ago. But its really weird how it varied, some of the 24k gold flowed out a and left the teeth bare. But dealing with the 24k is fine. Its the pink and green gold that is the PITA. It really is a weird thing, but then I have always heard that you never know what even a piece of steel will do when it has gone through the heat. Its obviously true for gold as well.

Powderhorn, thanks for the input, but these are gold alloys I mixed myself with a jewelr friend of mine, and its heat treating that caused the problem, have'nt got to the blueing stage yet.

 

[Mike Cirelli]

Since you used a copper backing you may be able too use some sort of salts that won't damage the steel but will corrode and dissolve the copper. I'll look through my resources when I have more time. You may want to contact an Assayer they deal with those sorts of chemicals everyday.

 

[Weldon47]

Scott,

I'm not looking at the piece so this advice may not fit the situation. If the piece itself is hardened successfully that could be of benefit to you at this point. Using a chisel made of a less hard material might allow you to remove the gold mechanically without affecting the steel. Also you may try air abrading with one of the tiny air erasers, masking off and protecting the good spots first. It does sound like an incredible PITA. Sorta sounds like the heat treatment got a little hot, maybe?

Good luck!

Weldon

 

[tincanart]

Scott, sounds like the golds and the solders melted together and created harder alloys and have brazed themselves to the steel. I think you will have to cut out everything by hand. The others are correct that the acids will damage the steel before all the gold is removed.

 

[Don Cowles]

Scott, I confess to being confused. I don't understand why the inlay was done prior to heat treat. Certainly the engraving should be done first, and all the inlay channels cut, but it seems to me that the actual inlay should not be done until the steel has been hardened. Am I way off base here?

 

[John B.]

Sorry to hear of your problem Scott.
What a mess.
As Weldon said, make a hard bronze flat graver and also a square graver to cut off the gold.
As you know, this should cut the gold without hurting the steel.
Then some final sanding and some recut might get you out of trouble.
Too bad that bad things happen to nice people.
Sure hope it wasn't your hammer project that went up in smoke.
Best of luck, John B.

 

[pilkguns]

no need for brass graverss, the metal is hard enough that carbide does'nt really touch it. its hell on the gravers though. it does'nt take long to dull them things up at all especially working around the teeth in the pocket areas.

when I post a photo essay of this knife I will discuss why what was done when

 

[BJREBUCK]

Mike, I Asked One Of Our Materials Engineers At My Day Job. He Recommended Trying Either
Ammonium Thiosulfate Or Thiourea. A 2% Solution With Distilled Water Should Work, However
You Should Test On A Hidden Area (4-5 Hours) To See If It Reacts/etches The Base Metal.
Good Luck,
Brian

 

[Mike Cirelli]

There you go Scott. You'll probably have to hop on the horse and ride into town for the chemicals Just kidding. Brian what's your day job just curious.

 

[Dave London]

Scott
I second the abrasive blasting, Glass beads, silicon etc etc some thing will cut and clean this mess up and with out to much damage to the item, Might have to mask of parts or shield parts , My two cents Dave And please let us know the outcome

 

[qndrgnsdd]

Scott, I wish I had better news for you but any chemical ie acid you try to use will attack the steel first then the copper then on up the periodic chart. The culprit is the solder. Gold and silver solders usually have some tin in them to lower the melting point to less than the alloy they are intended for. You can make green and red 18K alloys that are soft enough to inlay with out the copper back. I will be happy to supply formulas if you need them. The really bad news is that the only way to remove the now very goofed up alloy of metals is to cut scrape and sand, and hope that it did not become corrosive in its semi molten state. This is what happens when gold alloys are contaminated with lead/tin solders the solder superheats and eats into the copper and silver in the gold alloys completely ruining the gold alloy, and changing all its physical properties. If I can be of further help please contact me. I am a goldsmith of 35 years experience. owen@walkergoldsmiths.com

 

[pilkguns]

FWIW its worth, I took this crap out last weekend, all with individual graver cuts. Punishing on the gravers, and requiring multiple sharpenings. It had to be done, I actually hired another engraver locally to help to try to get the knife finished on time. Since glass and aluminum oxide was part of the final finish plan, I can assure you that those would not have been viable removal methods.

Owen, green gold is relatively soft and will move around without to much problem. I know of no alloy of pink gold that is not hard, and me and a goldsmith freind mixed alloys up about 10 years ago from 2k to 22 with multiple stops in between, and all of them were basically the same to work harden. And suprisingly, all were basically the same color pink. I have inlaid pink gold alone, it can be done, but it has to be where it is going in the first 2 or 3 blows or you are finished. I would only inlay pure pink gold where I had a solid back to hammer against. I would never inlay pink gold without a copper backer into something like a folding knife for fear of distorting something. -------All that to say, that has been my experince, and similar expereinces have been noted on other threads on this forum, but if you have a recipe for rose gold that is softer... I am all ears. I am also seeking the eternal secret of making blue gold.
thanks
Scott