Don
Cave Dweller
He wants you too, Malachi.
Member since December 2009
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Post by Don on Dec 19, 2014 12:35:05 GMT -5
Pickle doesn't remove the fire scale or fire "stain" that some call it. It's the purplish discoloration resulting from copper separating out of the sterling alloy. Pickling simply removes the black oxidization and flux residue.
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Post by rockjunquie on Dec 19, 2014 14:18:07 GMT -5
You're not removing the fire scale with a pickle pot? Phil, because so many people use the same word for two different things, it gets confusing. To remove what is commonly called firescale, or, as Don correctly calls it, the blackish oxidation, a pickle pot will do and I even use the Speed Brite for small quick jobs. However, the other "firescale", or, better yet -- "firestain", needs much more aggressive treatment. Firestain is a problem on a molecular level with copper being brought to the surface of the silver.
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Post by phil on Dec 19, 2014 15:28:23 GMT -5
You're not removing the fire scale with a pickle pot? Phil, because so many people use the same word for two different things, it gets confusing. To remove what is commonly called firescale, or, as Don correctly calls it, the blackish oxidation, a pickle pot will do and I even use the Speed Brite for small quick jobs. However, the other "firescale", or, better yet -- "firestain", needs much more aggressive treatment. Firestain is a problem on a molecular level with copper being brought to the surface of the silver. Aha. Thanks!
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zarguy
fully equipped rock polisher
Cedar City, Utah - rockhound heaven!
Member since December 2005
Posts: 1,791
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Post by zarguy on Dec 19, 2014 23:34:24 GMT -5
Don, I'm interested to see what the abrasive plastic pyramids accomplish. I doubt you'll remove firescale without manual labor.
Your best bet is to eliminate firescale from the equation. Then you may be able to use more automated polishing methods.
I've had some success with the boric acid/alcohol dip, but I still get firescale when I just can't get the solder to flow & I overheat the piece. Lynn
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zarguy
fully equipped rock polisher
Cedar City, Utah - rockhound heaven!
Member since December 2005
Posts: 1,791
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Post by zarguy on Dec 20, 2014 0:03:07 GMT -5
Tela, Does an ultrasonic cleaner eliminate the need to scrub sterling pieces between tripoli & rouge? Lynn
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Post by rockjunquie on Dec 20, 2014 18:15:05 GMT -5
Tela, Does an ultrasonic cleaner eliminate the need to scrub sterling pieces between tripoli & rouge? Lynn I'm not sure of the answer to that as I haven't tried it. I don't use an ultrasonic cleaner, mine is ionic. It puts a small electric current on the metal- just enough to pop off dirt and tarnish.
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Post by rockjunquie on Dec 20, 2014 18:20:11 GMT -5
I was very, very saddened to learn abt firestain. I had no clue what it was, where it came from or anything..... and then I got it. All my hard work ruined. It was extremely disappointing and made me want to give up. I haven't given up, but I am not as enthusiastic abt silversmithing anymore. Esp when one considers that firestain is virtually unavoidable.
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Post by phil on Dec 20, 2014 21:52:50 GMT -5
A cool way to get rid of it is via low current at home electro plate. I"m talking a 9 volt battery, some electrolyte, a silver anode and some time..... You're just plating dirty silver with fresh silver.....
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Don
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He wants you too, Malachi.
Member since December 2009
Posts: 2,616
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Post by Don on Dec 20, 2014 22:02:13 GMT -5
A boric acid and denatured alcohol dip prior to soldering helps keep most of the firestain away, but if you over heat it, it's still going to happen. I think avoiding the firestain comes down to prep and technique, knowing how to get the solder to flow where you want it before the metal gets overheated.
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gemfeller
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Post by gemfeller on Dec 20, 2014 23:28:46 GMT -5
Don, I used to do a lot of this. If your pieces have detail the gritted media will alter or remove it. I found I could automate a big part or the process but never found a way to avoid hand work completely. Keep us updated on your progress. The procedure outlined in your last post sounds close to the method I used to use. Good luck with this.
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jamesp
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Post by jamesp on Dec 21, 2014 8:02:29 GMT -5
I was very, very saddened to learn abt firestain. I had no clue what it was, where it came from or anything..... and then I got it. All my hard work ruined. It was extremely disappointing and made me want to give up. I haven't given up, but I am not as enthusiastic abt silversmithing anymore. Esp when one considers that firestain is virtually unavoidable. Soldering in general seems a challenge to keep neat and clean Tela. It is one of those skills I have difficulty with. it is unforgiving. Kudus to those that master it.
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Post by rockjunquie on Dec 21, 2014 16:49:11 GMT -5
I was very, very saddened to learn abt firestain. I had no clue what it was, where it came from or anything..... and then I got it. All my hard work ruined. It was extremely disappointing and made me want to give up. I haven't given up, but I am not as enthusiastic abt silversmithing anymore. Esp when one considers that firestain is virtually unavoidable. Soldering in general seems a challenge to keep neat and clean Tela. It is one of those skills I have difficulty with. it is unforgiving. Kudus to those that master it. Thanks James. That made me feel a bit better. I was really riding high when I began... only to be dashed by the rotten firestain.
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jamesp
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Member since October 2012
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Post by jamesp on Dec 21, 2014 17:27:23 GMT -5
Soldering in general seems a challenge to keep neat and clean Tela. It is one of those skills I have difficulty with. it is unforgiving. Kudus to those that master it. Thanks James. That made me feel a bit better. I was really riding high when I began... only to be dashed by the rotten firestain. The 2nd one from the left has solder showing. That is frustrating. It is almost irreversible to repair. Is that what you call fire stain ?? Or amateur soldering LOL
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Post by rockjunquie on Dec 21, 2014 17:30:50 GMT -5
jamesp Nope, firestain is a purpleish color cast on the bright white silver seen at certain angles to the light. If you look at the second video I posted earlier in this thread, it shows firestain pretty well. I don't know what it is called when the excess solder leaches.
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jamesp
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Post by jamesp on Dec 21, 2014 17:36:15 GMT -5
jamesp Nope, firestain is a purpleish color cast on the bright white silver seen at certain angles to the light. If you look at the second video I posted earlier in this thread, it shows firestain pretty well. I don't know what it is called when the excess solder leaches. Ah, missed the video. Will check that one out. thnx Tela
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Post by rockjunquie on Dec 21, 2014 17:38:25 GMT -5
jamesp Nope, firestain is a purpleish color cast on the bright white silver seen at certain angles to the light. If you look at the second video I posted earlier in this thread, it shows firestain pretty well. I don't know what it is called when the excess solder leaches. Ah, missed the video. Will check that one out. thnx Tela Actually, James, it may have been in the first one- can't remember now, but they are both worth watching.
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jamesp
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Post by jamesp on Dec 21, 2014 17:51:00 GMT -5
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gemfeller
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Post by gemfeller on Dec 21, 2014 20:54:07 GMT -5
Firestain, usually called fire scale, occurs when oxygen in the ambient air combines with copper in silver alloys or low-carat gold when heated to the 1,000-degree range. It forms cuprous oxide -- ugly dark blotches that show up usually during the polishing process. It can be polished away pretty easily from gold but silver's another story. Going back to abrasive grits can usually remove it from silver but it's a big hassle. Another removal method is with acid but that can be dangerous and has the drawback of removing metal over the entire piece, weakening thin areas and damaging detail.
The best solution is prevention: keeping oxygen from reaching the heated areas. The best method I've found is making a super-saturated solution of granulated boric acid in alcohol. Heat the metal slightly then dip it in the boric acid solution, using tongs. Flame the alcohol off and repeat the process 2 more times. The boric acid will leave a whitish layer on the metal that doesn't interfere with solder flow. After soldering leave the piece in a heated pickle solution for a few minutes longer than usual to remove the glaze. Prolonged heating of the work piece during soldering makes the fire scale problem worse.
Some "remove" fire scale by pickling but that really only covers the stain with a thin layer of fine silver that can wear off quickly. One caution about using boric acid/alcohol: alcohol burns with a nearly invisible flame. When you flame it off your work piece be careful that no lighted drops of alcohol drip onto flammable stuff on your bench or the floor. It can cause fires. Don't ask me how I know this.
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jamesp
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Member since October 2012
Posts: 36,158
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Post by jamesp on Dec 21, 2014 22:50:48 GMT -5
Firestain, usually called fire scale, occurs when oxygen in the ambient air combines with copper in silver alloys or low-carat gold when heated to the 1,000-degree range. It forms cuprous oxide -- ugly dark blotches that show up usually during the polishing process. It can be polished away pretty easily from gold but silver's another story. Going back to abrasive grits can usually remove it from silver but it's a big hassle. Another removal method is with acid but that can be dangerous and has the drawback of removing metal over the entire piece, weakening thin areas and damaging detail. The best solution is prevention: keeping oxygen from reaching the heated areas. The best method I've found is making a super-saturated solution of granulated boric acid in alcohol. Heat the metal slightly then dip it in the boric acid solution, using tongs. Flame the alcohol off and repeat the process 2 more times. The boric acid will leave a whitish layer on the metal that doesn't interfere with solder flow. After soldering leave the piece in a heated pickle solution for a few minutes longer than usual to remove the glaze. Prolonged heating of the work piece during soldering makes the fire scale problem worse. Some "remove" fire scale by pickling but that really only covers the stain with a thin layer of fine silver that can wear off quickly. One caution about using boric acid/alcohol: alcohol burns with a nearly invisible flame. When you flame it off your work piece be careful that no lighted drops of alcohol drip onto flammable stuff on your bench or the floor. It can cause fires. Don't ask me how I know this. I imagine you would have to go thru the abrasive range on a small area, like a lot of work. It must require a lot of experience. That's why you guys are silversmiths. Interesting that you could buy a piece of silver and have blemishes as it starts to wear. Unbeknownst to the buyer. In arc welding heavy argon gas is often released on the work to remove the oxygen. Guess that does not work with a gas torch. Best keep the proper fire extinguisher when the alcohol is being used.
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39don
starting to spend too much on rocks
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Post by 39don on Dec 21, 2014 23:13:57 GMT -5
I have learned to live with the nature of the beast!!!!!!!!!! I do one of two things remove it by polishing or oxidizing. This conversation about fire scale comes up when I am just starting to add a new topic on my silversmithing on the Forum. I'll start here first. James, one of your problems with the solder is you are using too much solder, lighten up a bit. A pendant I finished today had so much fire scale if I had polished/buffed it off my silver base plate (24gauge) would have been no more. I had purchased an oxidizer from Rio Grande recently so I wanted to try it out anyway. I oxidized it per directions and brushed it with a fine stainless steel brush. On this next pendant I used 22gauge as the base plate so I used a 3M Scotch-Brite abrasive wheel To remove all on the backside and tripoli followered by Zam on muslin on both front and back. Tela, I know how frustrating it gets when something like this happens but it's like your wire wrapping, you have your own style so you don't have to go out and buy from someone else. You can do it just keep trying. I still have melt downs........lol. 39don
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