Cleaning heavily tarnished copper

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Forty or fifty years ago, before PVC pipe became so common, buildings were often entirely plumbed with copper- which was more affordable then. Obivously the water lines were plumbed in copper, but oftentimes even the sewer lines in a quality house or building were plumbed with large diameter copper pipe. When remodeling these older building you sometimes run accross this big copper, but it can be corroded. Having some very tarnished pipe laying around I thought I'd try to clean it a smart way rather than wear my fingers to the bone using steel wool and 'Brasso'.

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This picture is of a short piece of dirty old 2 1/2" pipe. It probably came off an old well-head. The smaller pipes in the background are there for color reference.

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This image shows a coil of copper wire that was used as a sacrificial anode during a previous enperiment. Notice that there were origionally only two sizes of wire, one comming out of the straw - and the rest. The surface of the wire is pitted and in some places it has decreased in diameter or even separated.

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From this angle the errosion of the copper wire used as an anode can be seen beter. The blue solution is copper sulfate. Origionally a clear solution of mostly water and a little sulfuric acid (left over from filling a new motorcycle battery), this sloution turned blue in a very short time after driving DC current through it.

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This site explains simple anodizing and electrophoretic deposition. The image above is a test upon cartridge brass (which is about 30% zinc and 70% copper). The first 30-36 cartrige case on the left was the only one that was used as an anode. It is almost eaten through in places and showing odd pink and red colors in other places. The other four cases (used only as cathodes) show various degrees of scale or crust deposits. This coppered scum - some of which comes from the original tarnish on the electrodes, is what stuck to these cases . The effect was interesting but it was not an example of proper electroplating.

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This image shows the dirty segment of copper pipe and an equally dirty length of copper wire that is to be used as the other electrode in the upcomming electrolysis.

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This shows a large vinegar bottle cut in a way to suport the heavy copper pipe in an upright position. The diameter of the wire coil was enlarged and it was threaded into the bottle. Anode and cathode must make no electrical contact during electrolysis.

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