Pickling agent for copper

[Jeff02]

Sulfuric acid for a pickling agent, where to get small qtys, I ony need enough to make about a gallon of solution.
I am building a 3" boiler.

Thanks, Jeff

 

[firebird]

Hi Jeff

I used citric acid on my boiler build, much safer and works great. Its available from home brew stores. Its used for cleaning the bottles.

cheers

Rich

 

[Jeff02]

What Ratio of Acid to Water did you use??

Thanks!

 

[Julian]

Just make a very strong solution. It won't hurt you cos its basicly lemon acid. I mixed a very strong solution to restore a seventy year old model. It is slow but not damaging. It took two weeks to strip all the crud and paint back to metal.

The other thing that works well on copper, brass etc is coca cola but be warned it is like sulphuric....it will eat the metal if left too long and needs rinsing well. It unfortunately leaves sugar behind which needs washing off and like sulphuric any drops left inside or on the boiler will continue eating.

If you like coke try it on copper or put some in a tub and put a piece of fresh meat in it and leave it. It will disolve the meat! Now consider this...your throat, stomach and associated parts are raw meat. I don't drink it any more since this was shown to me 30 years ago.



Julian

 

[firebird]

Hi Jeff

As julian says the stronger the better. The stuff I get comes in small plastic bottles (aspirin bottle size). I use 4 of those in about a gallon of water. Thats strong enough to pickle a 3 inch dia by 6 inch long boiler tube overnight.

Cheers

Rich

 

[Noitoen]

If you like coke try it on copper or put some in a tub and put a piece of fresh meat in it and leave it. It will disolve the meat! Now consider this...your throat, stomach and associated parts are raw meat. I don't drink it any more since this was shown to me 30 years ago.

What is that compared that to the power of the acids in your stomach? I bet those acids would make a nice pickling agent. :big:

 

[hitandmissman]

OK, I am new to silver soldering. So here is my question. Why pickle? What happens if you don't pickle at all?

 

[shred]

A dip in the pickle before soldering cleans the metal nicely for soldering. After soldering it takes the flix residue and all off. Copper comes out pink but fades back to copper-colored with time.

 

[Kermit]

Pickling is easier way to remove remaining silver soldering paste. Unless you are willing to scratch it off 8).

LISTEN to that advice. I can attest to the difficulties of using isopropanol and a brass bristle brush to remove flux residues. Some finished assemblies cannot be wetted and only pure alcohol can be used to clean them. Hence the elbow grease with the brushes. One benefit is the finish achieved is far better than any pickle can provide since abrasion is wearing the soldered surfaces clean. To satisfy curiosity these are vacuum sealed and potted dual centertapped transformers useful for communications circuits. They are in a can with 12 glass beaded copper feed throughs and made the way they are for operation in high altitude or hard vacuum environments.

If I could soak them in some pickle I would tickled,
Kermit

 

[Jasonb]

I've recently been using the dry acid crystals sold in the UK by the likes of Chronos, only used them on a couple of steel fabrications but 20mins will remove all the black carbon deposits from the un-fluxed areas as well as all the flux residue. Just need to get it rinsed off and apply a quick spray of WD 40 otherwis eit starts rusting in seconds once rinsed, this will obviously not be a problem with non ferrous metals.

The advantage of the dry crystals is that they can be sent through the post.

Jason

 

[Metal Mickey]

As Jason says, Citric acid is the way to go. It works and its a lot safer (and easier to dispose off!) than H2SO4

 

[Mainer]

If you do want sulfuric acid, you can probably get it at an auto parts store as battery acid (though, with the pre-charged batteries these days, maybe not).

Given the success other people are reporting using citric acid, however, that sounds like a better way to go.

 

[Kermit]

If you do want sulfuric acid, you can probably get it at an auto parts store as battery acid (though, with the pre-charged batteries these days, maybe not).

Given the success other people are reporting using citric acid, however, that sounds like a better way to go.

The battery acid comes in little asprin sized tablets now as well. Check the Auto Parts Store near you.


Kermit

 

[Loose nut]

Auto part stores or ignition repair shops etc. stock Sulphuric acid, about 37%. Dilute it about 8 or 9 to 1 with distilled water for pickling copper, brass etc. It's not particularly dangerous at that level but wear goggles, to protect your eyes, when working with it. It will eat away at your clothes if splashed on them and may cause some dermatitis if your skin is contacted with it (I have had some on my skin without any problems if washed off fairly soon).

On the plus side it works very fast (much faster than citric acid) and leaves a good ready to solder finish.

Don't drop a hot piece of work in it to remove the flux, the steam that it produces is really acid vapor (this goes for the citric acid bath as well), bad for the sinuses and eyes. Drop the work in clean water first to cool it, this will break up the flux and then soak it in the pickle.

 

[deverett]

I have used old battery acid (and have quite a stock) as it comes out of the battery for pickling copper and also steel after silver soldering.

Don't leave steel in the pickle too long otherwise it gets pitted. Guess how I found out?!

Citric acid (available from home brew winemaking shops) may be the way to go these days.

Dave
The Emerald Isle

 

[PTsideshow]

The only problem with the citric acid is the amount you have to use compared to the sodium bisulfate (Pool Ph Reducer) and the cost of it the pool reducer is the cheapest, fastest and easiest to dispose of. Plus you can buy it any place that sells swimming/hot tub products and is cheap.
About a 1/2 cup of powder to gallon of water. Warm it up and it works faster. It is what is sold as safety pickle at the jewelry supply houses at a higher price.

The biggest problem with the citric acid is you need about 4 times as much for the same effect. And what they don't tell you is if you let it sit around for about a week or two it will work as a growth medium for some very interesting molds. You can always double duty it as your kids science fair project.

If you are having a hard time finding it try a industrial baking supply.(citric acid)

You can put salt on half a lemon and use it as an emergency pickle rub. Or salt and vinegar will work or even salt and ketchup will work slowly.
;D

 

[tomol409]

No mention has been made of the traditional way to clean the surface after pickling -- used by silversmiths for eons, is to scour with pumice powder. If not available use VIM. TOMOL.

 

[steamer]

Thanks Glen and Tomol!

Dave