Blue/Green corrosion on safe plaque

Warren63

Hi again. I have several safe plaques that have blue /green corrosion happening to them. Is there anything that will dissolve or break down without affecting the brass or patination? Can this corrosion pass on to other plaques it comes into contact with? I’ve noticed some plaques that have contact with others seem to have affected each other. I have had a look on the net for information but things seem to conflict each other and i dont want to cause any damage. Most of my plaques have had paint on at some time which i have removed so the majority do not have the original patination so having to clean overall would not be the end of the world but I thought if something was able to dissolve it would save a lot of work. Thanks once again for any help you guys can give. Respect.

Tom Gordon

Without moisture you arent going to get that, so solve your humidity problem first!
Dont sand blast them or they end up with a funny slightly greenish hue normally.
Try oxalic acid

mercury

As Tom said, keeping them away from humidity will help a great deal in preventing this from happening.

Also, avoid them touching eachother. When dissimilar metals are in contact, corrosion will occur.

Tomato sauce, lemon juice or oxalic acid will clean them, however long exposure to these will strip the patina. Tomato sauce and lemon juice are a bit milder than oxalic acid.

Once clean, wiping the plates with a lightly oiled cloth should help to protect them from moisture.

…Mark

Warren63

Thanks for the suggestions Tom/Mark. I think the contact of the plates is likely to be the problem as oppose to the humidity as they’re probably in the driest room in the house. Seems like manual cleaning is going to be the best bet. I was hoping someone would suggest something like the limescale dissolver Cillit Bang and then a quick run under the tap. (Wishful thinking). They are all Milner plaques that have been stacked on top of each other and it’s mainly the backs of them transferring it onto the fronts in patches. I suppose if I’ve put them away damp after cleaning it could partly be a moisture thing that has originally created the oxidation. Thanks once again for your help in resolving this problem and if anyone has any other solutions they will be gratefully received. Regards.

Tom Gordon

These plates are all likely to be brass, so I think that the most likely reason for corrosion is moisture or chemicals which either you have applied or have been drawn to the metal.

Warren63 wrote
Thanks for the suggestions Tom/Mark. I think the contact of the plates is likely to be the problem as oppose to the humidity as they’re probably in the driest room in the house. Seems like manual cleaning is going to be the best bet. I was hoping someone would suggest something like the limescale dissolver Cillit Bang and then a quick run under the tap. (Wishful thinking). They are all Milner plaques that have been stacked on top of each other and it’s mainly the backs of them transferring it onto the fronts in patches. I suppose if I’ve put them away damp after cleaning it could partly be a moisture thing that has originally created the oxidation. Thanks once again for your help in resolving this problem and if anyone has any other solutions they will be gratefully received. Regards.

[unknown]

Warren63

I never thought of the chemical related aspect Tom. They’ve had a wide range of experimental stripping methods tried on them. Paint stripper, lemon juice, vineger, tomato sauce, thinners, bleach and several others I’ve probably forgot. If I have not cleaned all the nooks and crannies out enough they could well have been sitting with some on for several years. A good wash and a scrub can’t harm them. I’ll get onto it asap. Thanks once again for your helpful suggestions.