Rust, the story we need to tell...

In Australia we have extremes of temperature and humidity and the humidity (water vapour in the air) can affect your badges! With all badge fronts, or as we call them; "domes", being made of plated steel (much the same material as "Tin" cans) these can suffer with the occasional outbreak of rust.

This is not a great problem and in all our years of business we have never had a problem with this. But it is worth mentioning for the sake of "completeness".
When you make a badge you cannot guarantee freedom from rust, A few years after manufacture you may see a slight discolouration appear on the surface of your paper artwork, it will look like a faint light brown patch of irregular shape with a darker tiny spot close to the centre of the stain.
These stains will gradually spread across the artwork until the whole artwork is covered. I have no proof but I suspect that this may be caused by a small imprefection in the plating process but it could equally be caused by "skin acids" that are present on all human skin and can be transferred by handling of the badge components. Another possible cause is acid that is present in most standard paper, which is why archival quality paper is marketed as "acid free".

See the attached image of a badge I bought over 35 years ago in London, you can clearly see the effect of the rust on the white background.
I should also point out that there are MANY very old badges sold on eBay (with photos) that show no sign of rust.

You can easily see the effect of rust without waiting years by taking a badge and dipping it in plain water, drying it and then leaving it for a couple of weeks!