Stopping the Rot: A Practical Look at Metal Conservation for Pin Collectors

This post explains how to identify different types of metal corrosion, the safest ways to remove surface grime from vintage enamel, and why standard household cleaners are often the biggest threat to your collection. You'll learn the technical difference between surface tarnish and deep-seated metal rot—knowledge that helps you decide when to scrub and when to step away from a piece entirely.

Collectors in the Pacific Northwest face a unique set of challenges. It's not just about the age of the pins; it's the environment we keep them in. When you're dealing with vintage enamel pins and medals—pieces often made of brass, copper, or mystery pot metal—you aren't just looking at a hobby. You're looking at a chemistry experiment that's been running for fifty years. If you don't understand the materials, you're going to destroy the very history you're trying to save. I've seen too many rare 1960s trade union pins ruined because someone thought a bit of vinegar and baking soda was a 'natural' way to make them shine. It isn't. It's an acid bath that eats the original plating and leaves the base metal vulnerable to the air.

Understanding the Base Metals

Before you even touch a cleaning cloth, you have to know what's under the enamel. Most vintage pins use a brass or copper base, often plated in gold, silver, or nickel. Cloisonné (hard enamel) is essentially glass fired at high temperatures. It's tough, but the metal around it isn't. Soft enamel, which is much more common in modern and mid-century pins, uses a paint-like resin that can be easily scratched or chemically dissolved. Then there's 'pot metal'—a generic term for low-melting-point alloys often containing zinc, lead, and tin. These are the most temperamental. They can develop 'zinc pest,' a structural breakdown that looks like tiny cracks or grey powder on the surface. Once this starts, you can't really 'clean' it away; you can only stabilize the environment to slow it down.

How do you clean vintage enamel pins without ruining them?

The first rule is simple: start with the least aggressive method possible and stop the moment you see an improvement. You don't need a lab full of chemicals. Most of the time, a dry microfiber cloth is all it takes to lift skin oils and light dust. If the grime is stubborn—maybe it's a pin that spent twenty years in a smoky VFW hall—you can move up to a damp cotton swab. Use distilled water. Tap water has minerals (and sometimes chlorine) that can react with the metal and leave spots. If that still doesn't work, a tiny drop of pH-neutral soap (like Dawn or a specialized conservation soap) is your limit. Never soak the pin. Water can get trapped behind the enamel or in the crevices of the pin back, leading to rust that you won't see until it's too late.

You'll want a set of high-quality tools for this. I recommend wooden toothpicks for picking out dirt from the recessed areas of soft enamel pins. Metal tools will scratch the plating—avoid them at all costs. For the metal edges, a soft-bristled toothbrush (extra soft, the kind for sensitive teeth) works well. Scrubbing should be light. You aren't trying to sand the piece down; you're just agitating the surface dirt so the soap can lift it. When you're done, drying is the most important part. Use a hair dryer on a 'cool' or 'low' setting to ensure every bit of moisture is gone from the pin post and the clasp mechanism.

For more technical details on how museums handle these materials, the