Regardless of the type of material used for awnings, boat and car covers and tarpaulins they all need some means of holding them securely in place. For the most part, bungee cords are used with temporary covers, making them easy to put on or remove while rope is often used for more permanent fastenings or when extra strength is needed to hold a cover in place. While the material of the cover and the type of tie-down used can vary, the one common issue is the integrity of the hole through which the tie-down material inserted.
Without a reinforcing grommet through the hole, the material will tear, eventually causing the tie-down to come loose and allow the cover to flap helplessly in the wind. Rubber grommets are commonly used in metal to protect wires or strings passing through the sharp edges, but for outdoor fabrics, brass grommets are the most popular. It is not necessarily because more people are enamored with the gold color of the copper-zinc alloy, but if they are coated with clear lacquer when new, they can withstand many years of outdoor use.
Although they have a low melting temperature and are malleable, brass grommets can provide protection for the material as well as the cord passing through the grommet. Typically, they are in two pieces and are either hammered into position or secured through the cloth using a grommet press. They are relatively easy to install as well as replace if they become damaged during typical use.
Other materials are also used for grommets in cloth, such as plastic and metal but brass grommets are one of the most popular materials in use for the outdoors. When properly coated they resist rust and will leave stains on the materials through which they are passed. Especially when used on light-colored fabrics, ensuring they do not leave a tell-tale stain around or running from the grommet protects the appearance of the material.
While brass grommets are most often used in outdoor applications due to their strength and durability to stand up to the weather, they are sometimes used indoors. Properly treated brass used indoors will last virtually forever, provided it is protected from damaging humidity and occasionally wiped dry. There are many different types of brass, determined by the alloy of the two metals, but the most common type used in brass grommets contains 33-percent zinc, compared to 40-percent zinc in Naval brass.