Collecting and displaying historical helmets is a popular and exciting hobby.  If you're just getting started there are a few things you need to know.

Most helmets are handmade of mild steel.  The higher quality helms are polished steel and not nickel or zinc plated.  The thin layer of nickel or zinc on plated helms tends to wear or flake off over time.  The down side of more authentic polished steel helms is that they require slightly more care.  These helms will rust over time and require periodic maintenance.

Cleaning of your helm can be accomplished with Brasso and Nevr-dul, both of which can be found at Wal-Mart.  After cleaning, a fine coat of WD-40 will help protect your helm from rust.  If your helm includes a horse hair plume it will often times be a little deformed from being packaged for an extended period of time.  It can be restored to its original condition by wetting with water and brushing it to the desired style.  Allow to dry or blow dry.  You may also dye the plume a different color if you choose. 

Another consideration when purchasing a helm is the thickness of the steel.  This will effect both the weight and strength of the helmet.  16 Ga steel is thicker than 18 Ga, and 14 Ga is thicker that 16 Ga.  18 gauge is perfect for collecting, costume parties, and reenactments.  If you anticipate actually taking a blow to the head, as in SCA competition, the helm must be at least 14-16 gauge steel, check with your local SCA officials.  Most helmets will require some form of padding for proper fit and comfort, whether it be an arming cap or your own custom made padding.

Hopefully this has answered some of your questions and happy collecting from the folks at KingsFolly.  If you found this guide helpful, please vote "Yes" below.