Choosing a Backing Type for Your Convex Mirror
The common question is, “What are the differences between indoor and outdoor mirrors.” In a nutshell, the main difference is the choice of backing for the convex mirror. With outdoor mirrors, you want to choose a plastic backing or galvanized steel. In most cases, the plastic back will be sufficient for outdoor conditions; however, we recommend the galvanized steel backing if the conditions are extreme.
Although the plastic and galvanized steel backings would be okay to use indoors, it will be overkill as hardboard backing will suffice. The hardboard backing is not weather resistant, so using it outdoors would not be a good choice.
Note on dome mirrors: Dome mirrors are typically not recommended for outdoor use dues to mounting problems and weather hazards. Domes are available with steel and plastic backings; it is overkill to use a backing at all for indoor use. One potential use for plastic backing might be to keep our dust and debris, but this can also be accomplished by placing a piece of cardboard over the top of the dome.
Backing Materials Used for Convex Security Mirrors
Hardboard backing – the pressed hardboard backing is suitable for indoor use and not recommended for outdoor use.
Heavy Duty Plastic backing – suitable for indoor and outdoor use. The plastic backing in our mirrors is called high-density polyethylene (HDPE) and is approximately 1/8” thick. Polyethylene or PE is the same material used in commercial-grade toilets and football helmets. The material is rigid and good against impact and abrasion resistance.
HDPE is highly corrosive resistant, making it an excellent choice in weather conditions, such as wet and sea-salt conditions—the material does well within temperature ranges of -60F to 180F without warping or breaking. It has less flex than steel (steel tends to expand and contract more in high and low temperatures), but with dings and dents, it tends to snap back in place better than steel.
Galvanized steel – The galvanized steel backing is 20-gauge steel. Although your specific requirements may call for steel, we believe the HDPE backing a better choice.