View samples of the many finish options available. Visit your local hardware store or specialty home improvement store to examine these finishes in person. The appearance of a metal finish can be very different when viewed online or in print compared to its actual appearance.
Aim for consistency in your hardware finishes. If your current hinges are brass, an aluminum doorknob may not be the best option. If surrounding metal items, like power outlets and light switch covers, are chrome, you may want to choose a silver-colored doorknob. Although it's generally acceptable to mix and match different color families (like brass and bronze), it's considered a decorating faux pas to match a brass doorknob with hardware that's silver or nickel-plated.
Consider the impact of weather on your doorknob. Most finishes, including steel and brass, can rust or corrode due to rain or other exterior elements. For knobs that will be installed on exterior doors, choose galvanized steel, aluminum or chrome. These metals won't rust, even after years of use.
Decide whether you want a modern look or a more rustic finish. Shiny brass or stainless steel knobs work best with a modern or industrial decor. Homeowners with more traditional or rustic designs should consider brushed or antiqued finishes. Oiled bronze and burnished finishes also offer a muted look that fits with more traditional decors.
Understand the maintenance requirements for each type of finish. Polished knobs are difficult to keep clean, and fighting fingerprints will be a constant battle. Brushed (matte) knobs are much easier to keep clean and help to mask grease and oil.
Consider that some finishes may change over time. Copper, bronze, pewter and nickel tend to develop a patina over time that can change their coloring dramatically. If you want your doorknob to maintain its look for years, stick with brass, stainless steel or chrome.
Check to see if antimicrobial coatings are available. Many doorknob manufacturers are now offering special coatings to keep germs and bacteria in check. This coating is invisible and kills germs for many years. Antimicrobial knobs are often used in hospitals and other buildings where germs are a major concern.