Cleaning Brass by Electrolysis

[dennishoy]

This appears hard work and electrolysis attacks the zinc element of the brass leading to surface discolouration (i.e. the copper begins to show through).

I use horolene concentrate from a supplier like this....

http://www.cousinsuk.com/catalog/7/1125/1350.aspx

I mix one part Horolene with seven parts water and use it again and again until it no longer works.
Immerse the item in warn solution for 10-15 minutes. Repeat until clean.

Horolene is just ammonium oxalate with a bit of green liquid soap added - you can make it easily from an oxalic acid solution - a teaspoon of oxalic acid crystals in a cup of warm water - plus a few ml of concentrated domestic ammonia solution and a couple of teaspoons of green liquid soap.

Soak for about 10 minutes - not more, rise thoroughly with distilled water, then methylated spirits, then dry with a hair dryer etc.

You can make a litre for well under a quid - Horolene is about 20 quid /litre

Oxalic acid is widely used for bleaching wood in cabinet making and restoration (removing stains from oak etc.) - you can get it in loads of places - I bought my last lot from a well known auction site... also used by bee-keepers as a safe treatment for varroa infestations...

Note that oxalic acid is toxic and you should avoid getting on your hands...

I get the impression there may be additional stuff in it.... I've tried a made-up oxalic acid solution a couple of times and it leeches the zinc from the brass leaving a 'coppery' surface stain which has to be removed by metal polish. Horolene doesn't exhibit this effect and leaves a nice, shiny brass finish (unless you forget and leave it in the cleaner overnight... Dohhh.). I bought a 5 litre can of Horolene a few years ago for £40 and am still using it. There is a newer alternative (called Horogrene ??) which has no ammonia or other unpleasant smell. I've not tried this, but read somewhere that the old stuff may be discontinued at some time due to environmental issues.