Copper Pickling Question?

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Harold_V
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Re: Copper Pickling Question?

Post by Harold_V » Wed May 07, 2014 3:03 pm

Bob D. wrote: Brass pickles well too but if the solution is used for copper it will give a coppery color to the brass.
One must use care when pickling brass, as the color you see develop is displaying the damage that is being done to the alloy. The percentage of zinc is high enough to permit selective dissolution, so it is rapidly dissolved, leaving behind the finely divided copper with which it is alloyed. If you leave a piece in the pickle long enough, it will disintegrate. The same thing is true of using (dilute) sulfuric acid.

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gwrdriver
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Re: Copper Pickling Question?

Post by gwrdriver » Wed May 07, 2014 4:47 pm

Bob D. wrote:I use a friendly solution of 1 gallon white vinegar mixed with 1 lb of table salt
I'll have to give this a try. I've been using Muriatic for years because it's cheap and readily available, but it's not the best solution. Also make it a practice never to touch a tool or even enter my workshop on a day that I've been handling pickled, fluxed, or silver soldered boiler bits, for obvious reasons. The FBI has my fingerprints, and that's enough.
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xo18thfa
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Re: Copper Pickling Question?

Post by xo18thfa » Wed May 07, 2014 8:45 pm

Citric acid is the best pickle -- bar none. It removes solder flux very quickly. Does not eat steel as muratic acid does. Citric acid is nowhere near as dangerous. No fumes. Does not burn skin.

It comes in crystal powder form. Just mix with water until no more dissolves. Probably have to order it from a chemical supply house. Been told that health food stores carry it. I got it from McMaster-Carr.
Bob Sorenson, Las Vegas, Nevada

jpfalt
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Re: Copper Pickling Question?

Post by jpfalt » Thu May 08, 2014 12:23 am

I have used Sparex #2, which is mainly sodium bisulphate with very good results. Followed by a clear water rinse, I usually don't have to brush or scrub. I usually use EZFlow solder with sta-silv flux or boric acid, I get good flow and wicking of the solder.

Howard Gorin
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Re: Copper Pickling Question?

Post by Howard Gorin » Thu May 08, 2014 2:26 am

The dry acid sold by swimming pool supply shops is also Sodium Bisulphate. It desolves in water and makes a weak sulpheric acid solution, It is less expensive then Sparex and more readly available, assuming you live in an area where swimming pools are used

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Re: Copper Pickling Question?

Post by Bruce » Thu May 08, 2014 9:48 am

Thanks everyone. I tried the vinegar and salt yesterday with my 6" diameter 24" long 1/8" boiler. It worked fine but required wire brush work. I will soon try each of the the other environmentally friendly pickings, such as the citric.

One question: What were those green colored ghostly flames shooting out of the barrel when I silver soldered after the vinegar/salt pickle????

I'm wondering if I did not rinse properly.

Bruce

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Bruce_Mowbray
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Re: Copper Pickling Question?

Post by Bruce_Mowbray » Thu May 08, 2014 1:09 pm

Pardon my delayed response.

I use a product called Oakite 31. The is a phosphoric acid product that is designed to dissolve brazing flux by just soaking. When I did my copper boiler for the 4-4-0. I cut the top off of a 55 gallon plastic barrel and set up my outdoor pickling station. The recommended dilution was 20:1 acid to water. Filled the barrel with the proper mixture and made a plywood top to keep things that don't belong in there out. I keep a bag of powdered limestone handy for neutralizing the bath once the project is finished. Test with litmus paper. I basically dipped the boiler in for an hour or so and it came out nice and clean. A few heavily fluxed areas needed to be scrubbed with a tooth brush. A full rinse with a garden hose and nozzle removed any residue.

This is a somewhat dangerous product. Although, it's a product used in cola based drinks-go figure. Be careful. Wear all appropriate PPE when doing this or any other projects involving acids or bases.

Bruce. Those green flames are the copper infused salts that remained after your pickle dried burning with the heat of your torch..
Bruce Mowbray
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TMB Manufacturing & Locomotive Works

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Re: Copper Pickling Question?

Post by Bruce » Thu May 08, 2014 1:48 pm

Thanks everyone but let's remember that this thread's main theme is environmentally friendly processes.. I already get great pickling with sulphuric acid, it does the job very well but want to move toward the green.


Bruce

Howard Gorin
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Re: Copper Pickling Question?

Post by Howard Gorin » Thu May 08, 2014 2:01 pm

Anything you use is going to have an environmental affect. The "pickle" and the flux.
Sulfuric acid is used by the barge load in industry.
The laundry detergent you use as an environmental impact.
There is no escaping some environmental change when you work or play.

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steamin10
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Re: Copper Pickling Question?

Post by steamin10 » Thu May 08, 2014 2:52 pm

Ya, weeelll! I look at MY environment, and try not to contaminate me. Acids and bases, organic chemistry for Vinegar, and salt (the chlirine- ide atoms at work here) and Phosphoric acids work well, ect. one may substitute another that can do the same work more or less. Which one are you confident in at pouring on the weeds next to your driveway? Neutralize? Fine, put acids on limestone drive, and its gone in seconds. Lets not get crazy, but use common sense, chemical cleaning is easier than snadblasting, or wire brushing, or polish with Comet and a buffer. Dont forget that mechanical means of cleaning with a stainless wire wheel, before fluxing, gives good results too.

I am sensative to Oils in the water that go somewhere else, and poisons for roses, and vegtables that kill my bees, and such like. I am glad somone meantioned the environmental cautions, that are some times learned the hard way with rusty Mirometers, and fingerprints on the work. I have a box of surgical gloves from Walgreens, I use for paints and chems. I highly recommend them for some work in the shop. Right now I am working fiberglass, and practice level 3, mask, gloves, and clothes changed, to isolate the infernal dust Created by sanding and working the stuff.

What does a prudent man do? Think!
Big Dave, former Millwright, Electrician, Environmental conditioning, and back yard Fixxit guy. Now retired, persuing boats, trains, and broken relics.
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Re: Copper Pickling Question?

Post by Bruce » Fri May 09, 2014 8:53 am

Thank you Big Dave, I agree with you but it's looking like this thread is being politicized so I would like to end it here. I got a lot of good answers to the original question. In the original thread, I mentioned that I was working in a shop that had requested that I use an environmentally friendly pickling solution as possible. I need to work in that shop, this project has outgrown my small patio.
The request was for solutions (pun) nothing else. Thanks to all.

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steamin10
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Re: Copper Pickling Question?

Post by steamin10 » Fri May 09, 2014 10:13 am

Sorry if you see politics in it. Like so many things, asking the question gives some options. I (we) try to make suggestions for what we did, and share that information. I do not speak for the board, but the answers are common as the materials and solutions you seek. I learn from the others too: example the Sodium Bisulphite available for pools. I will be checking. I myself have tried so many work arounds as I dont have a Chemical library for supplies in the feild. Once you have the information at hand, one must use some prudence, as there is always a critical few are negative with others activities. ( They view our hobbies as some 'Nutjob' sort of thing). To that end, I would rather support your actions with a dose of common sense for safty, as working with fire, lathes, hammers and chemicals, all have a diferent threat level to us. There is no excuse to be cavalier with any of it.

If I have misdirected or seem too critical, I apologize, as my comments were meant to support, not detract from, the general knowledge, and function of this board. Dave B.
Big Dave, former Millwright, Electrician, Environmental conditioning, and back yard Fixxit guy. Now retired, persuing boats, trains, and broken relics.
We have enough youth, how about a fountain of Smart. My computer beat me at chess, but not kickboxing
It is not getting caught in the rain, its learning to dance in it. People saying good morning, should have to prove it.

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