Cleaning copper

| | | | | |

When I make copper sculptures I wire brush the end product to clean it up. I am now making some miniature copper sculptures and it is hard to get into the tight spots with a wire brush to clean the residue left from brazing. Is there a way that I can dip them into a liquid solution to get the brazing residue cleaned up and then wire brush the rest to clean it up? Would there be a simple solution of something like pool chemicals or house hold cleaners? I am not interested in getting into acids.

Any help will be appreciated.
Dick Roberts
Dick Roberts Studio of Metal Art
www.metalartbydickroberts.com


Rich Waugh's picture

Well Dick, the household

Well Dick, the household products or pool products that will do what you need done are acids.  Vinegar, for instance, is 6% acetic acid, chemically speaking.  Swimming pool pH reducer, which makes a good pickling solution for removing firescale and flux/brazing residues, is a chemical called sodium bisulphite - that is, it is half-neutral sulfuric acid.

The process you need to accomplish is one that has to be done with either a lot of manual abrasion or chemically through the action of a mild acid.  Since I'm lazy and do trust myself to mix solutions properly, I opt for the chemical stripping rather than the hard work.


Dick Roberts's picture

Cleaning copper

Thanks Rich;

I guess I think of the acid that will eat flesh and make holes in clothing. Like battery acid. As a retired professional photographer I spent most of my career in the darkroom working with acedic acid. I mixed my hypo as well as the stop bath and was always using acid in washing out the silver haloids of the paper I was printing with, but I never thought of it as a dangerous chemical. After all I bought the chemicals from Kodak and then mixed them myself. I never used tongs, they were too clumsy. I just worked with my bare hands in the acedic acid and never had a problem. I guess I just need to try some of the methods you are talking about. I eat vinigar on my spinish but never thought of it as acid. Most of the way I have been learning about metal art has been from trial and error. It takes a little longer but I don't give up easily and usually will figure out something. I just thought maybe someone on the forum would have a simple and direct way of doing what I need to do. All I want to do is get rid of the fulx/brazing residue. Tomorrow I will look for some pH reducer.

Thanks,
Dick Roberts


Rich Waugh's picture

Boy, you're lucky you didn't

Boy, you're lucky you didn't get some really nasty burns from that acetic acid stop bath, Dick. When I had a darkroom I made my stop bath by diluting glacial acetic acid and if I got one teeny litle drop of the glacial acetic o my skin it burned clear to the bone if I didn't neutralize it immediately. That stuff is an incredible solvent for organic fats - like in skin and meat!

The pH reducer is much more gentle, and you'll be diluting it quite a ways. About a quarter cup of the crystals dissolved in a quart of water should do the job for you. Just heat it to between 140F and boiling and pickle the piece in it and it will come out clean and pink, ready for the wire brush.


Dick Roberts's picture

Cleaning copper

Thanks Rich. I didn't mean I used the acedic acid stright. It was diluted down a lot. I don't remember exactly the percentage, because it has been several years since I was in a darkroom (digital came along you know), but it seems like I mixed a gallon of diluted acedic acid and then when I poured it in a tray I diluted it again. Some guys had a problem with breaking out in a rash when they worked in a darkroom or some their finger nails would get funny looking; I never had that problem. When I studied photography in a fine arts college I was taught to use tonges, but when I had my own studio (in the real world) I was really busy with doing my high school senior portrait business and printing photos for all of the schools (I had under contract) yearbook photos and just didn't have time to mess with gloves or tonges. I was exposing a lot of paper of different subjects and then dumping it all in the developer and then pulling them out into the stop bath as needed and I didn't have time to dilly dally around. It was like an assembly line. One mistake was very costly. That was then and this is now. I now work in my small metal art shop attached to my home in a retirement community and am hoping to learn as much as I can to create something as I can think of it. I make items from 48" to 4" and it is the smallest items I am now concerned with.

You have been very helpful and you obviously have a lot of experience in working in metal. I do truly appreciate all of your advice and hang on every word of your advice.

Thanks,
Dick Roberts


crquack's picture

What Rich says. But if you

What Rich says. But if you do decide on mechanical cleaning I have made several nifty wheels from Scotchbrite pads: I have some which are 4" diameter for my buffer (actually wood lathe) and some which are about 3/4" diameter for my Dremel. You can also buy them ready made from Rio Grande. They work like charm.

crquack


Dick Roberts's picture

Cleaning copper

Thanks for your advice. However, when I say I need to clean something small, I mean really small. I can't even get to it with a Q-tip. I have a Dremel also and use it on other small things. I even use it on these miniature sculptures (where I can get to it) but I need to get behind a small axel on wheels, etc. This sculpture is 4"X1.5". That is why I was trying to find something liquid. I don't need that part shiny, but I would like to remove the brazing residue.

Thanks,
Dick


Rich Waugh's picture

Dick, A pretty good tool for

Dick,

A pretty good tool for getting into tiny little spaces on things like that is nothing more than bamboo skewer like they use for kebabs in Chinese restaurants - lots of supermarkets carry them. You can chuck a short piece one in your Dremel and put some polishing compound on the end of it and get into tight places with it.

Another good tool is a "trumming cord." This is nothing more than a piece of heavy string that you charge with polishing compound and pull back and forth through the small space. A good compound for this and the stick is either fine valve grinding compound from the auto parts store or "Tripoli" buffing compound from a jewelry supply.

Both of these methods still require that the brazing flux residue be removed first by pickling, of course - that stuff is like glass and hard to polish away.


Dick Roberts's picture

Cleaning copper

Rich - sounds sort of like dental flossing. Good ideas, but then you say I need to pickel first. Actually, the pickling is probably all I would need. I don't need it to shine, if I can just get rid of the residue.
Thanks again for your adice. I am learning, believe it or not - thanks to you. I think my main thing is I am concerned about respitory problems. I bought a small powder coating oven (up to 18") and then read where powder coating is a toxic and lethal problem and I never did use it. It just sat in one spot for about five years until a guy came along and offered to pay to take it away and put it in his shop. So that was what happened to my powder coating career. He bought it for 10 cents on my dollar. So he got a good deal and I was rid of something taking up space, that I wasn't using anyway. I am sure that everything would have been okay if I just took precaution, but I was busy with other things and just never gave it a try.
Dick