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Nickel plating on brass train models - restoration

April 11, 2008

I am collecting model railroad cars, these particular models are made of brass and plated to represent cars that were built from stainless steel. The original appearance was a very bright, almost chrome like surface. I have encountered two problems:
Some cars have small - dark - spots of corrosion , apparently originating from production defects or fingerprints. I assume thats what is called "nickel disease" and nothing can be done about this.
Many other cars have developed some kind of matte tarnish , which has covered the whole body quite evenly. Have tried to polish with several different brands with very little success, and even if I could remove the tarnish by polishing I would still have the problem that there are small details soldered to the bodies so I won't be able to reach every spot. To further complicate matters most of those cars have a fake "fluting" to represent the actual fluting of prototype cars, in fact this are shallow grooves done by photo etching during the initial production process.
Have read an several vintage magazines that a bath in ammonia ⇦this on eBay or Amazon [affil links] should remove oxidation from nickel plated models, I tried to soak one of those cars ( which is a duplicate so it is expendable should something go wrong ) for one hour with ammonia. There was some brightening up , I then polished again with my favorite polish - the car body looks definitely better but is still no match to a well preserved one, and I have spent a lot of time on it.


What I would like to know:
How about health risks when working with ammonia? My shop has a good extraction system.
Could I expect better results by immersing the body in a bath for a longer time? Is there a risk of damage to the basic brass body/ soldering joints ?
Any other recommendations for this problem?

Thanks Gerold

Gerold Eckl
hobbyist - Leopoldsdorf, Noe, Austria

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April 14, 2008

Somewhat old formula for cleaning nickel plated objects:
2% H2SO4 in pure etanol (according to Scientific american cyclopaedia of formulas,1910. edition-you can download it from www.thelitterbox.org ),short immersion(2 seconds) after that rinse it well!You can use ammonium citrate solution(pH 3,5-5%)too.Hope it helps and good luck!

Goran Budija
- Cerovski vrh Croatia