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Corrosion removal - tin plated cans

I have a specific problem relating to the removal of corrosion on tin plated cans. these items are being used in a display and have some small spots of very heavy corrosion where the tin has been abraded allowing the steel base to be exposed. I would like to find a suitable acid that will not affect the tin yet remove some of the corrosion so that the appearance of the items is improved. If anyone can help me out it would be appreciated.

James Engelbert
Museum - Edmonton, Alberta, Canada
April 15, 2010

Try next solution:2,6 gm sodium carbonate / washing soda [affil links]/2,6 gm sodium hydroxide/0.026 gm tannin/1 lit water, 50 °C temperature.If it is to weak you can try 47,5 gm sodium gluconate/47,5 gm citric acid [on eBay or Amazon] /4,9 gm tartaric acid [on eBay or Amazon]/1-10 lit water.Immersion in 20-50 gm paraffin in 1 lit petrol (3- 72 hours) can be useful but very slow.Cleaned objects must be waxed or lacquered (7,5% paraloid B72 or B67 must be ok, Renaissance wax is good brand) Hope it helps and good luck!

Goran Budija
- Cerovski vrh Croatia
April 21, 2010

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April 22, 2010

Goran,

Many thanks, I have all of this material in the lab and will test in the next few days. Nice to have a metals conservator assist with this as metals are not my area.

Regards,

James

James Engelbert
- Edmonton, Alberta, Canada

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Try it first on some metal scrap(old tinned cans)!Acid mixture can be mixed with corn starch and then with obtained gel you can treat only rusted spots.Petrol and paraffin is very good option but slow and needs many elbow grease.As final finish you may use fish oil/white spirit mixture too(20 parts fish oil/8o parts white spirit).After cleaning you can treat iron with 20 gm tannin/19 mll phosphoric acid/1 lit water solution(D-I-Y rust converter [on eBay or Amazon] ).If dark colour is problem you can use 10 gr sodium hexametaphosphate, 3,2 gm calcium chloride, 0.05 gm Sodium Nitrate [affil links], 1 lit water solution-that is Russian phosphating specially developed for conservation(contact object /solution 60-120 min, room temperature). Hope it helps and good luck!

Goran Budija
- Cerovski vrh Croatia
April 24, 2010